JP2009092195A - Static pressure fluid bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel structure by which a static fluid bearing can easily manufactured and constituted with high precision. <P>SOLUTION: A bearing body 200 of the static pressure bearing comprises a first bearing member 210 integrally having a first rugged end 211, and a second bearing member 220 integrally having a second rugged end 221 fittable in the axial direction with respect to the first rugged end. The first bearing member and the second bearing member are fitted in the axial direction in such a manner that the first rugged end and the second rugged end are combined with each other. A plurality of recessed groove 221g extending radially and communicating with a bearing gap G are radially formed at least at one of a first bearing side 211t and a second bearing side 221t. The first bearing side and the second bearing side abut on each other so that a plurality of throttles P are dispersed around an axis by a recessed groove. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydrostatic bearing that is supported by the pressure of a liquid such as gas, oil or the like, and more specifically, when used for a spindle bearing for inspection or precision machining of a disk used in an electronic storage medium. The present invention relates to a structure of a hydrostatic bearing suitable for the above.

  Many hydrostatic fluid bearings that supply a high pressure fluid to a bearing gap through a throttle and support a load applied to the shaft by the static pressure of the fluid have already been put into practical use. In particular, in a hydrostatic fluid bearing that requires high rigidity and high accuracy, it is required to reduce the bearing clearance and increase the fluid resistance of the throttle accordingly. For this reason, hydrostatic bearings need to be machined with high accuracy. Furthermore, in a spindle using a plurality of hydrostatic fluid bearings, the hydrostatic bearings themselves and the concentricity, cylindricity and straightness between them are high. There is a need to maintain accuracy.

  FIG. 3 is a schematic cross-sectional view schematically showing an example of a conventional spindle that supports a shaft 1 that receives a load in the radial direction by using two hydrostatic fluid bearings 2 and 2. The two hydrostatic fluid bearings 2 and 2 are fixed in a state where the first bearing member 2A and the second bearing member 2B are abutted in the axial direction. These inner diameters 21 are machined with high accuracy, and the roundness, cylindricity, straightness, concentricity with the outer diameter 22, and the perpendicularity of the end face 23 with respect to the inner diameter 21 need to sufficiently achieve the required accuracy. is there. In order to configure the spindle, a holder (housing) 3 serving as a spindle structure is prepared, a pair of bearing members 2A and 2B is inserted into the holder 3, a spacer 4 is inserted, and the other pair of bearing members 2A is inserted. , 2B are inserted. The roundness, cylindricity, and straightness of the inner diameter 31 of the holder 3 must satisfy the required accuracy, and the absolute dimension of the inner diameter 31 enables insertion of the first bearing member 2A and the second bearing member 2B. It is finished several micrometers larger than these outer diameters 22. The parallelism of both end faces 41, 41 of the spacer 4 is finished with sufficient accuracy to prevent the first bearing member 2A and the second bearing member 2B from being inclined. Further, the absolute dimension of the outer diameter 42 of the spacer 4 is finished smaller than the inner diameter 31 of the holder 3 in order to enable insertion into the holder 3.

Specific examples or improvements of the hydrostatic fluid bearing 2 as described above are described in, for example, Patent Document 1 below. As other conventional examples of hydrostatic fluid bearings, structures shown in the following Patent Documents 2 to 4 are known.
Japanese Patent No. 3779186 Japanese Examined Patent Publication No. 46-8044 (particularly the structure shown in FIGS. 1 and 2) Japanese Patent Publication No. 49-29526 (particularly the structure shown in FIGS. 1 and 2) Japanese Utility Model Publication No. 3-112121

  In order to construct a spindle using a plurality of conventional hydrostatic fluid bearings 2, as shown in FIG. 3, the first bearing member 2 </ b> A and the second bearing member 2 </ b> B constituting the hydrostatic fluid bearing 2 are attached to a holder 3. Therefore, even if the concentricity of the inner diameter 21 and the outer diameter 22 of the hydrostatic fluid bearing is finished to 0, the concentricity of the inner diameters of the plurality of hydrostatic fluid bearings, that is, the inner diameter The degree of alignment (alignment) causes an error corresponding to the difference between the holder inner diameter 31 and the fluid bearing outer diameter 22, that is, the gap fitting value. This is a big problem in a high rigidity and high precision spindle which is required to reduce the bearing clearance. Further, even when working, the concentricity of the inner diameter 21 / outer diameter 22 of the hydrostatic bearing 2, the perpendicularity to the inner diameter 21 of the end face 23, the roundness of the holder inner diameter 31, the cylindricity, the concentricity and the absolute dimension, It is necessary to process the parallelism of the both end faces 41 of the spacer 4 with high accuracy.

  That is, in order to configure a spindle using a hydrostatic bearing using a conventional technique, it is necessary to have a large number of parts and to process each part with high accuracy as described above. Nevertheless, the concentricity (alignment) of the plurality of hydrostatic fluid bearings will eventually cause an error by the gap fitting clearance value.

  Accordingly, an object of the present invention is to realize a novel structure that can easily manufacture a hydrostatic fluid bearing and can be constructed with high accuracy. In particular, when a plurality of hydrostatic fluid bearings are used, the concentricity of the inner diameters between the plurality of hydrostatic fluid bearings, that is, the error of the inner diameter alignment is as close to 0 as possible, and the number of parts is reduced. It is an object of the present invention to provide a structure or a manufacturing method suitable for allowing tolerance of parts and facilitating work.

  In order to achieve the above object, a hydrostatic fluid bearing of the present invention comprises a rotating body and a bearing body having a bearing surface facing the rotating body with a bearing gap interposed therebetween. In a hydrostatic fluid bearing that rotatably supports the rotating body by introducing a pressurized fluid through a throttle, the bearing body includes a first bearing surface portion that forms a part of the bearing surface, and a radial direction. A first bearing member integrally including a first uneven end portion provided in an uneven shape, a second bearing surface portion adjacent to the first bearing surface portion and constituting another part of the bearing surface, and a radial direction And a second bearing member integrally provided with a second concavo-convex end portion that is provided in a concavo-convex shape and is configured to be fitted in the axial direction with respect to the first concavo-convex end portion. The member and the second bearing member are a combination of the first uneven end portion and the second uneven end portion. The first non-bearing side portion provided on the opposite side to the first bearing surface portion in the radial direction among the first uneven end portions, and the radius of the second uneven end portions. The opposing surfaces of the second anti-bearing side portion provided on the opposite side of the second bearing surface portion in the direction are closely intimately configured over the entire circumference, and the radial direction of the first uneven end portion is At least one of the first bearing side portion provided on the first bearing surface portion side and the second bearing side portion provided on the second bearing surface portion in the radial direction among the second uneven end portions has a radius. A plurality of concave grooves that extend in the direction and communicate with the bearing gap are formed radially, and the first bearing side portion and the second bearing side portion abut each other so that a plurality of the diaphragms are formed around the axis by the concave grooves. Distributed and defined between the first bearing member and the second bearing member, An annular pressure chamber for the fluid supply in communication with the common aperture number, characterized in that it is configured.

  According to the present invention, the first bearing member and the second bearing member are fitted in the axial direction at the first concavo-convex end and the second concavo-convex end so that the first bearing surface and the second bearing surface are While constituting the bearing surface adjacent to each other and forming a plurality of throttles communicating with the pressure chamber by the concave groove, the first anti-bearing side portion and the second anti-bearing side portion are closely and airtightly constituted. Therefore, if each bearing member has a structure extending in the axial direction from the fitting end portion, the bearing body can be configured by the fitting structure of the first bearing member and the second bearing member. ) Is not necessary, and the assembly work can be facilitated and the number of parts can be reduced, and it is not necessary to incorporate the first bearing member and the second bearing member into the holder by gap fitting. Of the first bearing member and the second bearing member Prevents location shift, etc., circularity, cylindricity, it is possible to reduce the influence of the concentricity or the like.

  In the present specification, the meaning of “a2 provided on the side opposite to a1 in the radial direction of A” means that, in A (or with respect to A), when a1 is radially inward, a2 Is a portion provided on the radially outer side of A, and in A (or with respect to A), when a1 is on the radially outer side, a2 is a portion provided on the radially inner side of A. Let's show that there is. Also, the meaning of “b2 provided on the b1 side in the radial direction of B” means that when B1 is inward in the radial direction in B (or with respect to B), b2 is inward in the radial direction of B. In B (or with respect to B), when b1 is on the radially outer side, it indicates that b2 is a portion provided on the radially outer side of B.

  In particular, the first concave and convex end portions and the second concave and convex end portions are pressed into each other, thereby reliably preventing relative displacement between the first bearing member and the second bearing member during assembly. In addition, since the position change with time after assembly can be suppressed, it is possible to prevent the occurrence of problems such as a decrease in accuracy such as a bearing gap. That is, by positioning the bearing members with an interference fit, it is possible to improve the accuracy of each part while avoiding a positional shift or the like due to a conventional gap fit. The first bearing member and the second bearing member are preferably fixed to each other in the axial direction by a fixing means such as a bolt. Note that “fitting in the same manner as the second bearing member” does not mean that the fitting shape is the same, but when the first bearing member and the second bearing member are fitted in a press-fit state. This means that the first bearing member and the third bearing member are also fitted in a press-fit state.

  In the present invention, the first bearing member is formed with a first concave and convex opposite end portion configured to be concave and convex when viewed in the radial direction on the opposite side to the axial direction of the first concave and convex end portion, and the first bearing. A third bearing member provided with a third uneven end portion that fits in the same manner as the second bearing member to the first uneven opposite end portion of the member is provided; the first bearing member and the third bearing member; It is preferable that the throttle and the pressure chamber are configured in the same manner.

  According to this, since the second bearing member and the third bearing member are fitted to both sides of the first bearing member to constitute the bearing body, when the hydrostatic fluid bearing is constituted in at least two places in the axial direction. Further, since extra components such as spacers are not necessary, the manufacturing can be facilitated and the number of parts can be reduced. In addition, since the two hydrostatic bearings are fixed (in a press-fit state) at both ends of the integrally formed first bearing member, the consistency (adjustment) between the two hydrostatic bearings is fixed. Coreness, etc.) can be increased.

  In this case, the concavo-convex shape of the first concavo-convex opposite end portion may be formed symmetrically with respect to a symmetry plane orthogonal to the axial direction with respect to the concavo-convex shape of the first concavo-convex end portion, The concave / convex shape of the first concave / convex end portion may be formed into a shape that can be fitted to the concave / convex shape of the first concave / convex end portion. Further, the first bearing member has a fluid discharge path that opens to the bearing gap or an internal space that communicates with the bearing gap at an axially intermediate portion of the pair of throttles respectively provided at both ends of the first bearing member. When it is configured (when a pair of one-row bearing structures are provided in the axial direction), a continuous bearing gap is provided between the pair of throttles respectively provided at both ends of the first bearing member. When a fluid discharge path does not open in the bearing gap, and a fluid discharge path that opens to the bearing gap or an internal space communicating with the bearing gap is formed on both sides of the pair of throttles in the axial direction (the two-row bearing structure is If provided).

  Next, another hydrostatic fluid bearing of the present invention includes a rotating body and a bearing body having a bearing surface facing the rotating body via a bearing gap, and pressurizes the bearing gap. In the hydrostatic fluid bearing that rotatably supports the rotating body by guiding the fluid through the restriction, the bearing body includes a first bearing surface portion that constitutes a part of the bearing surface, and an axial end portion. A first bearing member integrally including an annular convex portion projecting annularly in the axial direction on the side of the first bearing surface portion in the radial direction, and another part of the bearing surface adjacent to the first bearing surface portion are configured. And a second bearing member integrally including a second bearing surface portion and an annular recess that is annularly recessed in the axial direction on the side of the second bearing surface portion in the radial direction at an end portion in the axial direction. The end of the bearing member and the end of the second bearing member are And the annular recess are fitted together in the axial direction, and a first side surface portion provided on the opposite side of the annular bearing from the first bearing surface portion in the radial direction, and the annular recess Provided between the opposed surface to the second side surface provided on the opposite side to the second bearing surface portion in the radial direction or on the opposite side of the annular convex portion from the first bearing surface portion in the radial direction. At least one of the opposing surfaces of the first end surface portion and the second end surface portion provided on the opposite side to the second bearing surface portion in the radial direction in the annular recess is in close contact and airtight over the entire circumference. A plurality of grooves extending in the radial direction and communicating with the bearing gap are formed radially on at least one of the axial front end surface of the annular convex portion and the axial bottom surface of the annular concave portion, The surface and the back bottom face each other so that the concave groove A plurality of throttles distributed around the axis, defined between the first and second pivot members, and an annular pressure for fluid supply that communicates in common with the plurality of throttles A chamber is constructed.

  According to the present invention, the first bearing member and the second bearing member are fitted in the axial direction in the annular convex portion and the annular concave portion, so that the first bearing surface portion and the second bearing surface portion are adjacent to each other. And a plurality of throttles communicating with the pressure chamber by the concave groove, the first side surface portion of the annular convex portion or the first end surface portion of the first bearing member, and the second side surface portion of the annular concave portion or Since the second end surface portion of the second bearing member is closely and airtightly configured, the bearing body can be configured by the fitting structure of the first bearing member and the second bearing member. A housing) is not required, and the assembly work can be facilitated and the number of parts can be reduced. In particular, since the first bearing member and the second bearing member are in a press-fit state, it is not necessary to incorporate the holder into the holder by a gap fit, so that the first bearing member and the second bearing member are displaced due to the gap fit. Can be prevented, and the influence on roundness, cylindricity, concentricity, etc. can be reduced.

  In the present invention, another annular convex portion is provided at the end opposite to the annular convex portion or the end portion provided with the annular concave portion of one of the first bearing member and the second bearing member. Alternatively, an annular recess is formed, and a third bearing member that fits in the same manner as the second bearing member with respect to the other annular projection or annular recess is further provided, and the one bearing member and the third bearing It is preferable that the throttle and the pressure chamber are similarly configured between the members.

  According to the present invention, since the first bearing member and the second bearing member constituting the bearing portion are fitted in the axial direction between the end portions configured to be rugged so that the holder can be attached to the holder. Since it can be made unnecessary, a hydrostatic bearing that can be easily manufactured and can be configured with high accuracy can be realized. In particular, when a plurality of hydrostatic fluid bearings are used, not only the structural accuracy of the hydrostatic fluid bearings themselves, but also the concentricity of the inner diameters between the bearings, that is, the error in the alignment of the inner diameters is reduced to zero. It is possible to obtain an excellent effect that it is possible to reduce the number of parts, and to allow the precision of the parts to be made easier and make the work easier.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. First, a basic configuration example of an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a basic configuration example of the present invention (however, it is embodied in that a spindle is formed by using a plurality of hydrostatic fluid bearings, a bearing body that surrounds a rotating body composed of a shaft body, etc.). It is a schematic sectional drawing which shows typically. As shown in FIG. 1, in this basic configuration example, the bearing body 200 that pivotally supports the rotating body 100 is fitted to the first bearing member 210 and one end 211 in the axis X direction of the first bearing member 210. A second bearing member 220 that fits together, and a third bearing member 230 that fits into the other end 212 of the first bearing member 210. Although not particularly limited, in the illustrated example, the rotating body 100 is configured as a columnar shaft body, and the bearing body 200 is configured in a cylindrical shape into which the rotating body 100 can be inserted.

  Both end portions 211 and 212 of the first bearing member 210 are configured to be uneven when viewed in the radial direction, and constitute a first uneven end portion 211 and a first uneven opposite end portion 212. In addition, one end of the second bearing member 220 is a second uneven end 221 that can be fitted to the first uneven end 211 and is configured to be uneven when viewed in the radial direction. Further, one end portion of the third bearing member 230 is a third uneven end portion 231 configured to be uneven as viewed in the radial direction, which can be fitted to the first uneven opposite end portion 212.

  The concavo-convex shape of each of the end portions only needs to be configured to be concavo-convex when viewed at least in the radial direction, and in particular, the convex portion and the concave portion are each formed in an annular shape over the entire circumference around the axis X. Preferably it is. In the case of the illustrated example, an annular convex portion 211A is formed in the radially inner portion of the first uneven end portion 211, and a first end surface portion 211B is provided in the radially outer portion. The first end surface portion 211B is not particularly limited, but is a flat surface (perpendicular to the axis X) in the illustrated example. Further, an annular recess 221A is formed in the radially inner portion of the second uneven end portion 221, and the second end face portion 221B is formed in the radially outer portion of the second uneven end portion 221 in a manner that can be fitted to the first uneven end portion 211. Is provided. The second end surface portion 221B is not particularly limited, but is a flat surface (perpendicular to the axis X) in the illustrated example. Further, an annular convex portion 212A is provided on the radially inner portion of the first concave and convex opposite end portion 212, and a first opposite end surface portion 212B is provided on the radially outer portion, respectively. The third concave and convex end portion 231 is provided with an annular recess 231A in the radially inner portion and the third end face portion 231B in the radially outer portion. In the illustrated example, the first opposite end surface portion 212B and the third end surface portion 231B are flat surfaces that are in close contact with each other, like the first end surface portion 211B and the second end surface portion 221B.

  The tip surface 211t of the annular convex portion 211A in the axial direction is brought into contact with the inner bottom surface 221t of the annular concave portion 221A, and the first side surface portion 211s (the outer surface on the radially outer side) of the annular convex portion 211A. The portion) is in close contact with the second side surface portion 221s (the radially inner side surface portion) of the annular recess 221A, and is configured to be airtight. Further, the first end surface portion 211B is in close contact with the second end surface portion 221B and is airtight. In this case, only the first side surface portion 211s and the second side surface portion 221s may be closely and airtightly configured, or only the first end surface portion 211B and the second end surface portion 221B may be closely and airtightly configured. May be. Here, the first side surface portion 211s and the first end surface portion 211B correspond to the first anti-bearing side portion, and the second side surface portion 221s and the second end surface portion 221B correspond to the second anti-bearing side portion. ing. In addition, such a structure is similarly comprised also in the fitting part of the 1st uneven | corrugated anti-end part 212 and the 3rd uneven | corrugated edge part 231. FIG.

  A concave groove 221g extending in the radial direction and communicating with the bearing gap G is formed on the surface of the inner bottom surface 221t of the annular concave portion 221A, and the diaphragm P is constituted by the concave groove 221g and the tip surface 211t. Here, the diaphragm P is preferably configured to form a slot diaphragm by forming the concave groove 221g into a wide groove shape, but the cross-sectional shape of the flow path of the diaphragm P is not particularly limited. May be included. In any case, a plurality of the concave grooves 221g are provided radially around the axis X, and a plurality of apertures P are distributed around the axis X (preferably evenly). In order to form the diaphragm P, not only the concave groove 221g is provided in the back bottom surface 221t, but a concave groove may be provided in the front end surface 211t instead, and a concave groove is formed in both the back bottom surface 221t and the front end surface 211t. Grooves may be formed. Here, the tip surface 211t corresponds to the first bearing side portion, and the back bottom surface 221t corresponds to the second bearing side portion.

  The concave groove 221g communicates with an annular groove 221h formed on the outer side in the radial direction of the back bottom surface 221t. The annular groove 221h is formed in an annular shape around the axis X, and forms a pressure chamber R between the tip surface 211t. The pressure chamber R communicates with the plurality of throttles P to supply fluid at an equal pressure, and communicates with a fluid supply path (air supply path Q) described later. Here, instead of the annular groove 221h, an annular groove may be formed on the tip surface 211t, or an annular groove may be formed on both the back bottom surface 221t and the tip surface 211t. Further, the annular groove may be formed in a portion of the first side surface portion 211s and / or the second side surface portion 221s on the tip surface 211t or the back bottom surface 221t side. The concave groove 231g and the annular groove 231h are configured in the same manner as described above.

  A first bearing surface portion 213 is formed on the inner peripheral portion of the first uneven end portion 211, and a second bearing surface portion 223 is formed on the inner peripheral portion of the second uneven end portion 221 adjacent thereto. The first bearing surface portion 213 and the second bearing surface portion 223 constitute a bearing surface 201 of a hydrostatic fluid bearing, and face the outer peripheral surface of the rotating body 1 with a bearing gap G interposed therebetween. The bearing surface 201 forms a (coaxial) cylindrical surface corresponding to the outer peripheral surface of the rotating body 1. Similarly, a first anti-bearing surface portion 214 is formed on the inner peripheral portion of the first concave / convex anti-end portion 212, and a third bearing surface portion 233 is adjacent to the inner peripheral portion of the third concave / convex end portion 231. Thus, the bearing surface 202 is configured in the same manner as described above.

  The first bearing member 210 and the second bearing member 220 are fitted. In particular, the annular convex portion 211A and the annular concave portion 221A are press-fitted. In this case, it is preferable that the inner diameter of the second side surface portion 221s is press-fitted with an interference of several micrometers to several tens of micrometers (2 to 60 μm) with respect to the outer diameter of the first side surface portion 211s. . As a result, the positional accuracy between the bearing members (during assembly and after assembly) can be increased. The tightening allowance is appropriately set depending on the rigidity of the material of the first bearing member 210 and the second bearing member 220 and the dimensions of the members. In particular, it is desirable that the first bearing member 210 and the second bearing member 220 be lightly press-fitted so that the dimensional change of the bearing surface 201 is within an allowable range even if the first bearing member 210 and the second bearing member 220 are once press-fitted and then removed and re-fitted. The relationship between the first bearing member 210 and the third bearing member 230 is the same as described above.

  The first bearing member 210 and the second bearing member 220 are preferably fixed to each other by a fixing means such as a bolt B. In the case of the illustrated example, the bolt B fixes both bearing members in the axial direction. The same applies between the first bearing member 210 and the third bearing member 230.

  In this basic configuration example, the single row air supply bearing is configured at two locations in the axial direction by the above-described configuration. In this basic configuration example, an air supply path Q which is a fluid supply path communicates with the pressure chamber R, and a gas such as compressed air is introduced through the air supply path Q. In the illustrated example, a common air supply path Q formed so as to extend in the axial direction inside the first bearing member 210, the second bearing member 220, and the third bearing member 230 communicates with the two pressure chambers R together. It has a structure. When the opening portion of the air supply path Q is provided at the end in the axial direction of the bearing body for the convenience of the bearing structure and other structures, it is preferable that the supply extending in the axial direction preferably extends into the plurality of bearing members as shown in the figure. It is desirable to configure the air path Q. However, in the present invention, it is sufficient that the fluid supply path has a structure capable of supplying a fluid to the pressure chamber R. Generally, at least one of the bearing members (for example, the first bearing member 210) is used. ) Is sufficient.

  In addition, an exhaust path S that is a fluid discharge path is formed inside the first bearing member 210, and the exhaust path S opens to an internal space T that communicates with the bearing gap G in the middle portion between the two throttles P. . The internal space T is formed by an annular groove formed between the bearing surfaces 201 and 202.

  In the basic configuration example of the embodiment described above, the first bearing member 210 and the second bearing member 220 or the third bearing member 230 are fitted, and the first uneven end portion 211 and the second uneven end portion 221, or Since the first concave-convex anti-end surface portion 212 and the third concave-convex end portion 231 are in a press-fitted state, relative positioning accuracy at the time of assembly and after assembly can be ensured, and a high-precision hydrostatic bearing. Can be configured. In addition, since the fluid sealability can be easily obtained by the fitting portions of these bearing members, the bearing structure can be configured without using a holder (casing) separately, and the number of parts can be reduced. It becomes possible to facilitate.

  The second bearing member 220 and the third bearing member 230 are press-fitted into both end faces of the first bearing member 210 with a tightening margin of several to several tens of micrometers, so that the first bearing member 210, the second bearing member 220, and the second bearing member 210 are inserted. The three bearing members 230 are in a pressurized state and fixed with screws B in the axial direction so that they are in close contact with each other and are kept airtight. At this time, the concentricity of the annular convex portion 211A projecting annularly in the axial direction radially inward of the first bearing member 210 and the first bearing surface portion 213 forming the bearing gap G near the central portion in the axial direction, and the second If the concentricity of the annular recess 221A of the bearing member 220 and the second bearing surface portion 223 is finished with high accuracy, the concentricity of the bearing surface 201 after the first bearing member 210 and the second bearing member 220 are press-fitted and brought into close contact with each other. Straightness and cylindricity are ensured with high accuracy. The same applies to the bearing surface 202 constituted by the first anti-bearing surface portion 214 and the third bearing surface portion 233. Furthermore, if necessary, the bearing surfaces 201 and 202 are subjected to simultaneous integral grinding after press-fitting and tight screwing, so that the alignment degree of a plurality of hydrostatic fluid bearings can be made as close to zero as possible. .

  Furthermore, since the first bearing member 210 is a structure such as a spindle, which will be described later, a holder and a spacer are not necessary, and the number of parts that require high-precision machining can be reduced. That is, in the specific configuration of this basic configuration example, the first bearing member 210, the second bearing member 220, and the third bearing member 230 function as a housing that is a structure such as a spindle. It itself also functions as a spacer between two hydrostatic fluid bearings.

  In the above-described embodiment, the first uneven end 211 and the first uneven opposite end 212 are formed at both ends of the first bearing member 210, and the annular protrusion 211 </ b> A is provided at the radially inner side of each end. , 212A are formed, but unlike this, annular recesses are formed on both radially inner sides of both ends, and annular ends are formed at the ends of the second bearing member 220 and the third bearing member 230 corresponding to these. A convex part may be provided. Furthermore, the end of the second bearing member 220 and the third bearing member 230 may be formed correspondingly to the same annular protrusion provided on one of both ends and the annular recess on the other. Further, in the above embodiment, an annular convex portion or an annular concave portion is provided on the inside in the radial direction of each bearing member. The uneven shape of the uneven end portion is not limited to the above embodiment. These points are the same in other examples described below.

  FIG. 2 is a modification showing a bearing structure having a different form from the basic configuration example. Here, the same reference numerals are given to portions corresponding to the basic configuration example. This example shows a case where a plurality of bearing members are fitted on both sides of the first bearing member 310. That is, the second bearing member 320 and the third bearing member 330 are press-fitted and fitted to both sides of the first bearing member 310, and the fourth bearing member 340 is further press-fitted and fitted to the second bearing member 320. The fifth bearing member 350 is further press-fitted and fitted to the third bearing member 330. In this case as well, various variations can be applied as described above. In this illustrated example, two-row air supply bearings are formed at two locations in the axial direction, thereby realizing a bearing structure with higher bearing rigidity. However, in this example, the second bearing member 320 and the third bearing member 330 may be provided with fluid discharge paths, respectively, so that a plurality of single-row air supply bearings may be configured in an axially arranged manner. It is.

  Next, a manufacturing method of the basic configuration example of the above embodiment will be described. A first bearing member 210, a second bearing member 220, and a third bearing member 230 are respectively prepared, and once they are press-fitted together to form a bearing body temporarily. In this case, these press-fit states are set so that a tightening margin is set in advance so that the surface accuracy of the bearing surfaces 201 and 202 is within an allowable range even after the fitting is once removed and re-fitted. And This first fitting step is a step of fitting a plurality of bearing members so as to be in a completed state.

  Then, in this fitted state, the bearing surfaces 201 and 202 are formed by grinding, polishing, or the like to obtain a required surface accuracy. This bearing surface forming step is a step for obtaining the required bearing surface accuracy when each bearing member is in a fitted state.

  Thereafter, the first bearing member 210, the second bearing member 220, and the third bearing member 230 are disengaged and separated, and the bearing surface 201 of the diaphragm P such as the concave groove 221g and the tip surface 211t facing the groove 221g. , 202 are removed, polished, or dust is removed. This opening edge processing step is an optimization processing step for the opening of the aperture P, such as preventing clogging of the aperture P generated in the bearing surface forming step and removing burrs.

  Finally, the first bearing member 210, the second bearing member 220, and the third bearing member 230 are again press-fitted and fitted to form an integral bearing body. The bearing body is completed by this second (second) fitting process.

  FIG. 4 is a schematic longitudinal sectional view showing the main part when the structure of the hydrostatic bearing according to the present invention is applied to a spindle. The spindle includes a first bearing member 510 that is inserted through the spindle shaft 400, a second bearing member 520 that is fitted into both end portions of the first bearing member 510, and is press-fitted. And a third bearing member 530. A throttle P and a pressure chamber R similar to those described above are formed between the bearing members, and support the spindle shaft 400 in the radial direction.

  The spindle shaft 400 is basically formed in a cylindrical shape, but has a flange portion 401 projecting in a radial direction in a part thereof, and the flange portion 401 is slightly different from the thrust bearing member 540 opposed to both sides in the axial direction. It is fitted via a bearing gap H in the axial direction. In the thrust bearing member 540, there are formed a throttle U and a pressure chamber V which are opposed to the flange 401 on both sides in the axial direction and open in the axial direction in the bearing gap H, and support the spindle shaft 400 in the thrust direction. To do. In this thrust bearing structure, the concave-convex relationship of the above structure is reversed, an annular groove is formed in the spindle shaft 400, and a flange-like portion projecting inward is inserted into the annular groove via a bearing gap. The provided bearing member may be provided. The thrust bearing member 540 is fixed to the second bearing member 520 on the one hand, and supported and fixed by the annular fixing member 541 in the radial direction and the annular fixing member 542 in the axial direction on the other hand. A bolt or the like (not shown) is used as a fixing means for each part.

  Also in this application example, at least one of the first bearing member 510, the second bearing member 520, and the third bearing member 530 is provided with an air supply path 501 that is a fluid supply path. In the case of the illustrated example, the fluid supply path 501 is configured inside each bearing member so as to penetrate the first bearing member 510, the second bearing member 520, and the third bearing member 530 in the axial direction. The air supply path 501 opens at the end face of the third bearing member 530 and is connected to a supply pipe (not shown). The air supply path 501 communicates with the pressure chambers R and V, and fluid is supplied to the bearing gaps G and H via the throttles P and U. Further, exhaust paths 502, 503, and 504 that are fluid discharge paths are formed in the first bearing member 510 and the thrust bearing member 540.

In the spindle shown in FIG. 4, air having a gauge pressure of 5 kgf / cm ² (= 490 kPa) is used as a lubricating fluid, rigidity against a radial load k = 5 kgf / μm (= 49 N / μm), and eccentricity. It was designed to have a load capacity W at 25 = 25 kgf (= 245 N).

  On the other hand, FIG. 5 shows the performance of the same design target (rigidity k = 5 kgf / μm (= 49 N / μm) with respect to radial load) and load capacity at an eccentricity of 0.5 using a conventional hydrostatic bearing. 3 shows a design example of a spindle having W = 25 kgf (= 245 N), where the corresponding parts are given the same reference numerals as in FIG. Since it is necessary to incorporate two sets of bearing members 2A and 2B into the holder 3 via the spacer 4 to constitute the fluid bearing, the number of parts increases, the assembly work is complicated, and the holder 3 It is necessary to mount the four bearing members 2A, 2B with a clearance fit, and it is difficult to increase the concentricity, cylindricity, straightness and alignment.

  FIG. 6 shows the relationship between the rigidity ks and flow rate Q per hydrostatic bearing and the radial gap Cr of the bearing. In order to obtain a rigidity k = 5 kgf / μm (= 49 N / μm) against a radial load with the spindle shown in FIGS. 4 and 5 using this hydrostatic fluid bearing, the radial gap Cr is set to Cr = 8 to 11 μm ( About 10 μm).

  In order to configure a spindle using a hydrostatic bearing according to the prior art, the hydrostatic bearing must be inserted into the holder with a gap of several μm as described above. Assuming that a hydrostatic fluid bearing is inserted into the holder with a clearance fit of 5 μm, the concentricity (alignment degree, that is, alignment error) of the two hydrostatic fluid bearings is equal to the inner diameter of the hydrostatic fluid bearing. Even if the outer diameter is processed with an ideal accuracy of 0, an error of a clearance fit of 5 μm is generated. This is 50% of the radial clearance Cr = 8 to 11 μm (about 10 μm) of the hydrostatic fluid bearing required to obtain the rigidity k = 5 kgf / μm (= 49 N / μm) with respect to the radial load by the spindle. Expressed by the rate ε, ε reaches 0.5. That is, the eccentricity ε = 0.5 and the load capacity W becomes W = 0. If the shaft is further displaced from this state in order to exhibit the design target load capacity W = 25 kgf (= 245 N), the shaft comes into contact with the bearing.

By using the hydrostatic fluid bearing according to the present invention, the concentricity (alignment degree, that is, alignment error) of the plurality of hydrostatic fluid bearings is ensured, and further, if necessary, after press-fitting and tight screwing, If the bearing surfaces (cylindrical inner surface, 201 and 202 in FIG. 1) are simultaneously and integrally ground, the concentricity of the bearing surfaces 201 and 202, that is, the alignment degree of a plurality of hydrostatic fluid bearings, can be as close to zero as possible. A plurality of hydrostatic bearings with a radial gap Cr = 8 to 11 (10) μm are used, air with a gauge pressure of 5 kgf / cm ² (= 490 kPa) is used as a lubricating fluid, and rigidity k against a radial load is obtained. = 5 kgf / μm (= 49 N / μm), a spindle having a load capacity W = 25 kgf (= 245 N) at an eccentricity of 0.5 can be realized.

  As described above, it is difficult to realize a spindle having the performance of the design target when using the hydrostatic bearing according to the prior art, but the performance of the design target is improved by using the hydrostatic bearing according to the present invention. A satisfactory spindle can be realized.

  In the above embodiment, air is used as the fluid, but other fluids, for example, liquids such as oil, and other fluid substances can be used. In particular, it is desirable to use a fluid with high lubricity. In addition, even in a case where the positional relationship between the inner side and the outer side in the radial direction of the rotating body and the bearing body is reversed, that is, when the bearing body is installed at the center and the rotating body is configured to surround the bearing surface on the outer periphery of the bearing body. The same effects as described above can be obtained.

The schematic longitudinal cross-sectional view which shows the basic structural example of embodiment of the hydrostatic fluid bearing which concerns on this invention. The schematic longitudinal cross-sectional view which shows the modification of a basic structural example. The schematic longitudinal cross-sectional view of the bearing structure using the conventional hydrostatic fluid bearing. The schematic longitudinal cross-sectional view which shows the spindle structure using the hydrostatic bearing of embodiment. The schematic longitudinal cross-sectional view which shows the spindle structure using the conventional hydrostatic fluid bearing. The graph which shows the relationship between the rigidity and flow volume per one hydrostatic fluid bearing, and the radial clearance Cr of a bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Rotating body, 200 ... Bearing body, 201, 202 ... Bearing surface, 210 ... 1st bearing member, 211 ... 1st uneven | corrugated edge part, 211A ... Annular convex part, 211B ... 1st end surface part, 211t ... Tip surface, 211s, 221s ... first side surface portion, 212 ... first concave / convex anti-end portion, 212A ... annular convex portion, 212B ... first anti-end surface portion, 213 ... first bearing surface portion, 220 ... second bearing member, 221 ... second Concavo-convex end portion, 221A ... annular recess, 221B ... second end face portion, 221t ... back bottom surface, 223 ... second bearing surface portion, 230 ... third bearing member, 231 ... third concavo-convex end portion, 231A ... annular recess, 231B ... Third end face, G, H: Bearing gap, P, U: Restriction, R, V: Pressure chamber

Claims (6)

A rotating body and a bearing body having a bearing surface opposed to the rotating body through a bearing gap are provided, and the rotating body can be rotated by guiding a pressurized fluid through the throttle to the bearing gap. In the hydrostatic bearing supported by
The bearing body includes a first bearing member integrally forming a first bearing surface portion constituting a part of the bearing surface and a first uneven end portion provided in an uneven shape when viewed in the radial direction, and the first bearing member. A second bearing surface portion that is adjacent to the bearing surface portion and constitutes another part of the bearing surface, and is provided in a concavo-convex shape when viewed in the radial direction, and can be fitted in the axial direction with respect to the first concavo-convex end portion. A second bearing member integrally having the second uneven end portion configured,
The first bearing member and the second bearing member are fitted in the axial direction in such a manner that the first uneven end portion and the second uneven end portion are combined, and the radial direction of the first uneven end portion is A first anti-bearing side portion provided on the side opposite to the first bearing surface portion, and a second anti-bearing side portion provided on the side opposite to the second bearing surface portion in the radial direction among the second uneven end portions. The opposing surfaces of the two are closely connected and airtight over the entire circumference.
The first bearing side portion provided on the first bearing surface portion in the radial direction of the first uneven end portion, and the second bearing surface portion in the radial direction of the second uneven end portion. Further, at least one of the second bearing side portions is radially formed with a plurality of concave grooves extending in the radial direction and communicating with the bearing gap, and the first bearing side portion and the second bearing side portion are abutted with each other. And the plurality of apertures are dispersed around the axis by the concave groove,
A hydrostatic fluid bearing, wherein an annular pressure chamber for fluid supply is defined between the first bearing member and the second bearing member and communicates in common with the plurality of throttles.   The hydrostatic bearing member according to claim 1, wherein the first bearing member and the second bearing member are fitted in a press-fitted state.   The first bearing member is formed with a first concave and convex end opposite to the first concave and convex end portion in an axial direction opposite to the first concave and convex end portion in the radial direction, and the first concave and convex end portion of the first bearing member. A third bearing member having a third concave and convex end that fits in the same manner as the second bearing member with respect to one concave and convex end is provided, and the third bearing member is provided between the first bearing member and the third bearing member. 3. The hydrostatic bearing according to claim 1, wherein the throttle and the pressure chamber are configured similarly. A rotating body and a bearing body having a bearing surface opposed to the rotating body through a bearing gap are provided, and the rotating body can be rotated by guiding a pressurized fluid through the throttle to the bearing gap. In the hydrostatic bearing supported by
The bearing body integrally includes a first bearing surface portion constituting a part of the bearing surface, and an annular convex portion protruding annularly in the axial direction on the side of the first bearing surface portion in the radial direction at the end portion in the axial direction. A first bearing member, a second bearing surface portion adjacent to the first bearing surface portion and constituting another part of the bearing surface, and a side of the second bearing surface portion in the radial direction at the end in the axial direction And a second bearing member integrally having an annular recess that is annularly recessed in the axial direction.
The first bearing member and the second bearing member are fitted in the axial direction in a mode in which the annular convex portion and the annular concave portion are combined,
A first side surface provided on the opposite side to the first bearing surface portion in the radial direction in the annular convex portion, and a first side portion provided on the opposite side to the second bearing surface portion in the radial direction in the annular recess. A first end surface portion provided on the opposite side to the first bearing surface portion in the radial direction of the annular convex portion, and the second radial portion of the annular concave portion. At least one of the surfaces facing the second end surface portion provided on the side opposite to the bearing surface portion is in close contact and is hermetically configured over the entire circumference,
A plurality of grooves extending in the radial direction and communicating with the bearing gap are formed radially on at least one of the axial front end surface of the annular convex portion and the axial bottom surface of the annular concave portion, and the front end surface A plurality of the apertures are dispersed around the axis by the concave groove by being in contact with the back bottom surface,
A hydrostatic fluid bearing, wherein an annular pressure chamber for fluid supply is defined between the first bearing member and the second bearing member and communicates in common with the plurality of throttles.   The hydrostatic bearing member according to claim 4, wherein the first bearing member and the second bearing member are fitted in a press-fitted state.   Another annular convex portion or annular concave portion is provided at the end of the first bearing member and the second bearing member opposite to the end provided with the annular convex portion or the annular concave portion. A third bearing member that is formed and fitted to the other annular convex portion or the annular concave portion in the same manner as the second bearing member, and is provided between the one bearing member and the third bearing member. The hydrostatic bearing according to claim 4 or 5, wherein the throttle and the pressure chamber are configured similarly.

Images