Rotary support device and support mechanism position adjustment mechanism for shaft support device

Abstract

A support mechanism (40) for rotatably supporting both axial ends of a screw shaft (21) comprises: a bearing unit (41) which has a movement-side bearing housing (51) and a pair of angular contact ball bearings (53) that are internally fitted to the movement-side bearing housing (51); a support base (43) which is provided to one side of the bearing unit (41) in the axial direction and through which the screw shaft (21) is inserted; and a housing position adjustment mechanism (60) which is provided between the bearing unit (41) and the support base (43). The housing position adjustment mechanism (60) is provided with: a support-base-side member (61) which is provided to the support base (43) side; a bearing-housing-side member (62) which is provided to the bearing housing (51) side and which is axially movable relative to the support-base-side member (61); a foam member (90) which is disposed in a pressure chamber (66) that is formed between the support-base-side member (61) and the bearing-housing-side member (62), and which has a foam core layer and a solid skin layer that covers the periphery of the foam core layer; and a working fluid (70) which is filled into spaces outside the foam member (90) in the pressure chamber (66). Thus, it is possible to continuously and stably maintain support rigidity in the axial direction even if the axial length of the rotary shaft changes due to the effects of heat.

Description

Rotation support device and support mechanism position adjustment mechanism for shaft support device

[0001] The present invention relates to a rotation support device that supports a rotation shaft such as a ball screw feed device or a spindle device, and to a support mechanism position adjustment mechanism for a shaft support device that supports a shaft.

[0002] Ball screw feed devices require high axial rigidity to maintain the feed accuracy of the screw shaft. Conventionally, a common method for providing rigidity to the screw shaft of a ball screw device is to combine and preload multiple angular bearings, place them at one or both ends of the screw shaft, and support the screw shaft in the axial direction. In addition, when thermal expansion of the screw shaft is taken into consideration, a method is used in which axial tension is applied to the screw shaft in advance to elongate it by a predetermined amount. Patent Document 1 describes a method in which tension is applied to the feed screw (screw shaft) in advance by adjusting the axial dimension of a spacer, and further includes a pretensioning mechanism that uses a disc spring or fluid pressure to move the bearing axially and apply tension to the feed screw when the feed screw elongates beyond the pretension due to temperature rise.

[0003] Japanese Utility Model Registration No. 2573982

[0004] However, excessive loads, such as pretension or pretension, applied to the feed screw can place a heavy load on the bearing, potentially damaging it. For this reason, a disc spring or an externally supplied fluid, as seen in the pretension mechanism described in Patent Document 1, is typically used to prevent excessive axial loads from being applied to the bearing. However, disc springs, as seen in the pretension mechanism described in Patent Document 1, weaken the load as the shaft elongates, and can only accommodate a temperature rise of 3 to 4 degrees. In machining centers, ball screws often experience temperature rises of more than 4 degrees, which prevents the disc springs from applying sufficient load, resulting in a decrease in axial support rigidity. Furthermore, hydraulic systems that apply loads hydraulically by supplying fluid from an external source require external devices such as a hydraulic pump, increase the size of the ball screw feed device, and result in increased costs and additional energy consumption. Furthermore, these issues exist not only in ball screw feed devices but also in rotation support devices, such as spindle devices, in which both axial ends of a rotating shaft are rotatably supported by a pair of support mechanisms.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a rotation support device and a support mechanism position adjustment mechanism for a shaft support device that can continuously and stably maintain axial support rigidity even if the axial length of the rotating shaft changes due to the effects of heat.

[0006] The above object of the present invention can be achieved by the following configuration. [1] A rotary support device comprising a rotating shaft and a pair of support mechanisms rotatably supporting both axial ends of the rotating shaft, one of the pair of support mechanisms comprising: a bearing unit comprising a bearing housing and a bearing that rotatably supports the rotating shaft relative to the bearing housing and is capable of supporting an axial load; a support base through which the rotating shaft passes or is arranged around the rotating shaft; and a housing position adjustment mechanism disposed between the bearing unit and the support base, wherein the housing position adjustment mechanism comprises: a support base side member provided on the support base side and through which the rotating shaft passes or is arranged around the rotating shaft; a bearing housing side member provided on the bearing housing side and through which the rotating shaft passes or is arranged around the rotating shaft, and is movable axially relative to the support base side member; a foam member disposed in a pressure chamber formed between the support base side member and the bearing housing side member, the foam member having a foam core layer and at least one of a solid skin layer and a cover member covering at least a portion of the periphery of the foam core layer; a working fluid filled in the space within the pressure chamber other than the foam member; [2] A support mechanism position adjustment mechanism for a shaft support device comprising a shaft and a pair of support mechanisms provided at both axial ends of the shaft to support the shaft, the support mechanism position adjustment mechanism for a shaft support device being provided on one of the pair of support mechanisms, wherein one of the pair of support mechanisms has a support through which the shaft passes or is arranged around the shaft, the support mechanism comprising: a first member provided on one of the shaft side and the support side, and through which the shaft can pass or be arranged around the axis, a second member provided on the other of the shaft side and the support side, and through which the shaft can pass or be arranged around the axis, movable axially relative to the first member, and forming an accommodation space between itself and the first member, a foam member provided in the accommodation space, and having a foam core layer and at least one of a solid skin layer and a cover member covering at least a portion of the periphery of the foam core layer, and a working fluid filling the space within the accommodation space other than the foam member.

[0007] According to the rotation support device of the present invention, even if the axial length of the rotating shaft changes due to the influence of heat, the axial support rigidity can be continuously and stably maintained. Furthermore, since the foam member is disposed in the pressure chamber, it is not necessarily necessary to have an external accumulator or pump, and a compact configuration can be achieved.

[0008] Furthermore, the support mechanism position adjustment mechanism for the shaft support device of the present invention can continuously and stably maintain axial support rigidity even if the axial length of the shaft changes due to the influence of heat. Furthermore, because the foamed member is placed inside the pressure chamber, it is not necessarily necessary to have an accumulator or pump outside, allowing for a compact configuration.

[0009] 1 is a cross-sectional view of a table feed system of a machine tool to which a ball screw feed device according to a first embodiment of the present invention is applied. FIG. 2 is an enlarged cross-sectional view of a support mechanism equipped with the housing position adjustment mechanism shown in FIG. 1. FIG. 3 is a view taken along an arrow A in FIG. 2. FIG. 4 is a cross-sectional view showing an example of a foam member. FIG. 5 is a diagram schematically showing a process for manufacturing a foam member by foam injection molding. FIG. 6 is a side view showing one modified example of a foam member. (a) and (b) are cross-sectional views showing foam members according to first and second modified examples of the first embodiment. FIG. 7 is a cross-sectional view showing a foam member according to a third modified example of the first embodiment. (a) is a side view showing a foam member according to a fourth modified example of the first embodiment, and (b) is a cross-sectional view taken along line IX-IX of (a) of (b). (a) to (d) are cross-sectional views of pressure chambers in which foam members according to fifth to eighth modified examples of the first embodiment are disposed. FIG. 7 corresponds to FIG. 2 of a ball screw feed device according to an eighth modified example of the first embodiment. FIG. 8 corresponds to FIG. 2 of a ball screw feed device according to a second embodiment of the present invention. FIG. 9 is a graph conceptually showing the composition of forces generated by a plurality of foam members according to the second embodiment. FIG. 10 corresponds to FIG. 2 of a ball screw feed device according to a third embodiment of the present invention. 15A and 15B are enlarged views of a portion XVI of a ball screw feed device according to a fourth embodiment of the present invention; (a) to (c) are enlarged cross-sectional views of a main portion showing an example in which a wear-resistant member is applied to the seal groove of a ball screw feed device according to a modification of the fourth embodiment; (b) a view corresponding to FIG. 2 of a ball screw feed device according to a fifth embodiment of the present invention; (c) a view corresponding to FIG. 2 of a ball screw feed device according to a sixth embodiment of the present invention; (d) a view corresponding to FIG. 2 of a modified bearing unit in which a pair of angular contact ball bearings are paired back to back in the first to sixth embodiments; (e) a view corresponding to FIG. 2 of another modified bearing unit in which a pair of angular contact ball bearings are paired in parallel in the first to sixth embodiments; (a) is a schematic side view showing a first example in which a housing position adjustment mechanism is formed by multiple pressure chambers; (b) is a schematic side view showing a second example in which a housing position adjustment mechanism is formed by multiple pressure chambers; (a) is a schematic side view showing a third example in which a housing position adjustment mechanism is formed by multiple pressure chambers; and (b) is a schematic side view showing a fourth example in which a housing position adjustment mechanism is formed by multiple pressure chambers.23(a) is a schematic side view showing a fifth example in which the housing position adjustment mechanism is configured with multiple pressure chambers. It is a cross-sectional view taken along line XXV-XXV in FIG. 23(a). It is a view corresponding to FIG. 2 of a ball screw feed device according to a seventh embodiment of the present invention. It is a view corresponding to FIG. 2 of a ball screw feed device according to a first modified example of the seventh embodiment. It is a view corresponding to FIG. 2 of a ball screw feed device according to a second modified example of the seventh embodiment. It is a view corresponding to FIG. 2 of a ball screw feed device according to a third modified example of the seventh embodiment. It is an enlarged view of the XXX portion in FIG. 29. It is a view corresponding to FIG. 2 of a ball screw feed device according to a fourth modified example of the seventh embodiment. It is a view corresponding to FIG. 2 of a ball screw feed device according to a fifth modified example of the seventh embodiment. It is a view corresponding to FIG. 2 of a ball screw feed device according to an eighth embodiment of the present invention. (a) is an enlarged cross-sectional view corresponding to FIG. 2 in a phase in which an oil supply passage formed in a bearing housing side member is provided to fill the pressure chamber with working fluid, and (b) is a cross-sectional view showing a modified example of the lock plug bolt in (a). 34(a) is a cross-sectional view of a stopper plug used in place of the stopper bolt of FIG. 34(a), (b) is a cross-sectional view showing an example in which the stopper plug of (a) and a disk-shaped member are combined, (c) is a cross-sectional view showing a modified example of the disk-shaped member of (b), and (d) is a cross-sectional view showing another modified example of the disk-shaped member of (b). 34(a) is a cross-sectional view of a table feed system of a machine tool to which a ball screw feed device according to a modified example of the present invention is applied. 34(b) is a cross-sectional view showing a first example of a housing position adjustment mechanism in which a support base is disposed on the axial end side of a bearing unit. 34(c) is a cross-sectional view showing a second example of a housing position adjustment mechanism in which a support base is disposed on the axial end side of a bearing unit. 34(d) is a cross-sectional view showing a third example of a housing position adjustment mechanism in which a support base is disposed on the axial end side of a bearing unit. 34(d) is a cross-sectional view showing a fourth example of a housing position adjustment mechanism in which a support base is disposed on the axial end side of a bearing unit. 34(a) is a cross-sectional view showing a rotation support device according to the present invention. 34(b) is a cross-sectional view showing another rotation support device according to the present invention. 34(c) is a cross-sectional view showing a shaft support device to which a support mechanism position adjustment mechanism according to the present invention is applied. FIG. 44 is an enlarged view of a portion XLIV of FIG. 43.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a ball screw feed device, which is an example of a rotation support device or a shaft support device according to the present invention, will be described in detail with reference to the drawings.

[0011] (First Embodiment) Fig. 1 shows a table feed system of a machine tool to which a ball screw feed device of the first embodiment is applied. With reference to Figs. 1 to 3, the axial direction of a screw shaft 21 of a ball screw feed device 20 (the left-right direction in Fig. 1) is defined as the X direction, the direction parallel to the mounting surface 1a of a base 1 and perpendicular to the axial direction of the screw shaft 21 (the direction perpendicular to the plane of the paper in Fig. 1) is defined as the Y direction, and the direction perpendicular to the mounting surface 1a of the base 1 (the up-down direction in Fig. 1) is defined as the Z direction. In Fig. 2 and corresponding figures, dotted lines indicate bolt fastening locations.

[0012] The table feed system 10 includes a moving table 11 fixed to a nut 23 of a ball screw feed device 20. The moving table 11 is configured to be movable in the X direction by driving a screw shaft 21 of the ball screw feed device 20 with a drive motor 12. The moving table 11 is provided with a pair of linear guides 13 (only one of which is shown in FIG. 1 ) on both sides of the ball screw feed device 20 in the Y direction. Each linear guide 13 includes a guide rail 15 disposed on the base 1 via a rail mounting base 14 in parallel to the screw shaft 21, and two sliders 16 fixed to the underside of the moving table 11 and mounted across the guide rails 15. When the drive motor 12 rotates the screw shaft 21, the moving table 11 is guided by the pair of linear guides 13 and moves back and forth linearly together with the nut 23.

[0013] The ball screw feed device 20 comprises a screw shaft 21 having a spiral screw groove 21b formed on its outer peripheral surface, a nut 23 arranged around the screw shaft 21, having a spiral screw groove (not shown) formed on its inner peripheral surface, and fitted into a nut housing 22 fixed to the underside of the moving table 11, and a plurality of balls (not shown) arranged so as to roll freely between the screw groove of the nut 23 and the screw groove 21b of the screw shaft 21.

[0014] The screw shaft 21 includes a large-diameter portion 24 formed in the axial center and having a screw groove 21b, and small-diameter portions 25 formed at both axial ends of the large-diameter portion 24. A male thread 25a is formed on the outer peripheral surface of the tip end of the small-diameter portion 25, and a small-diameter shaft portion 27 is provided at the tip end of one side (the right side in the figure) of the screw shaft 21. The small-diameter shaft portion 27 is connected to the rotating shaft 12a of the drive motor 12 via a coupling 28.

[0015] In addition, one side of the screw shaft 21, to which the drive motor 12 is connected, is rotatably supported by a first support mechanism 30, and the other side of the screw shaft 21 (the left side in the figure) is rotatably supported by a second support mechanism 40.

[0016] The first support mechanism 30 includes a fixed-side bearing housing 31 fixed to the base 1, and a pair of angular contact ball bearings 33, 33 arranged in a face-to-face combination to rotatably support the screw shaft 21 relative to the fixed-side bearing housing 31. Each of the pair of angular contact ball bearings 33, 33 includes an outer ring 34 fitted inside the fixed-side bearing housing 31, an inner ring 35 fitted outside the small diameter portion 25 of the screw shaft 21, and a plurality of balls 36 rollably disposed between the outer ring 34 and the inner ring 35 with a contact angle therebetween.

[0017] The pair of angular contact ball bearings 33, 33 has an outer ring 34 of the axially inner angular contact ball bearing 33 abutting against the inward flange 31a of the fixed-side bearing housing 31, and the outer ring 34 of the axially outer angular contact ball bearing 33 fixed by an outer ring holder 37 fastened to the fixed-side bearing housing 31. The inner ring 35 of the axially inner angular contact ball bearing 33 abuts against the step 21a between the large-diameter portion 24 and the small-diameter portion 25 of the screw shaft 21, and the inner ring 35 of the axially outer angular contact ball bearing 33 is fastened by a fastening nut 38a that screws onto the male threads 25a. Therefore, the first support mechanism 30 supports the screw shaft 21 with the axial position of the screw shaft 21 fixed.

[0018] 2 and 3, the second support mechanism 40 includes a bearing unit 41 disposed at the other end of the screw shaft 21, a support base 43 fixed to the base 1 axially centrally of the bearing unit 41, and a housing position adjustment mechanism 60 disposed between the bearing unit 41 and the support base 43. The support base 43 is provided with a through-hole 43a through which the screw shaft 21 passes.

[0019] The bearing unit 41 includes a moving-side bearing housing 51 and a pair of angular contact ball bearings 53, 53 that rotatably support the screw shaft 21 relative to the moving-side bearing housing 51. The pair of angular contact ball bearings 53, 53 include an outer ring 54 that fits inside the moving-side bearing housing 51, an inner ring 55 that fits outside the small diameter portion 25 of the screw shaft 21, and a plurality of balls 56 that are rotatably disposed between the outer ring 54 and the inner ring 55 with a contact angle therebetween.

[0020] In the pair of angular contact ball bearings 53, 53, the outer ring 54 of the axially inner angular contact ball bearing 53 abuts against the inward flange 51 a of the moving-side bearing housing 51, and the outer ring 54 of the axially outer angular contact ball bearing 53 is fastened by an outer ring holder 47 fastened and fixed to the moving-side bearing housing 51, so that each outer ring 54, 54 is positioned axially with respect to the moving-side bearing housing 51. Also, the inner ring 55 of the angular contact ball bearing 53 arranged axially outward is fastened by a fastening nut 38 b that threads onto the male thread 25 a via a spacer 48. In other words, the pair of angular contact ball bearings 53, 53, the moving-side bearing housing 51, and the outer ring holder 47 can be unitized as a bearing unit 41 with a predetermined preload applied to the pair of angular contact ball bearings 53, 53 arranged face-to-face, and this bearing unit 41 can be easily attached to the screw shaft 21 and the housing position adjustment mechanism 60, respectively. In this configuration, the moving-side bearing housing 51 can be integrated with the bearing housing side member 62 as needed.

[0021] The housing position adjustment mechanism 60 is provided on the support base 43 side and includes a support base side member 61 through which the screw shaft 21 passes, and a bearing housing side member 62 provided on the movable-side bearing housing 51 side and movable in the axial direction relative to the support base side member 61. The support base side member 61 and the bearing housing side member 62 face each other in the axial direction.

[0022] The support base side member 61 has an annular portion 61a protruding toward the support base 43 side, which fits into a through hole 43a of the support base 43, and is fixed to the support base 43 with a plurality of bolts (not shown). The bearing housing side member 62 has an annular portion 62a protruding toward the moving-side bearing housing 51 side, which fits into the inward flange 51a, and is fixed to the moving-side bearing housing 51 with a plurality of bolts 63 (see FIG. 3).

[0023] Furthermore, a bottomed annular recess 64 that opens toward the support base side member 61 (one axial side) is provided on the side surface of the bearing housing side member 62 that faces the support base side member 61. Meanwhile, an annular protrusion 65 that protrudes into the annular recess 64 toward the bearing housing side member 62 (the other axial side) is provided on the side surface of the support base side member 61 that faces the bearing housing side member 62. The annular recess 64 and the annular protrusion 65 are slidably fitted together in the axial direction, and an annular pressure chamber 66 is formed between the bottom surface, inward surface 64a, and outward surface 64b of the annular recess 64 and the tip surface of the annular protrusion 65.

[0024] A foam member 90 configured to have a sealed structure is disposed within the pressure chamber 66, and the space within the pressure chamber 66 other than the foam member 90 is filled with the working fluid 70.

[0025] The foam member 90 is formed in an annular shape with an elliptical cross section having an inner diameter larger than the outward surface 64b of the annular recess 64 and an outer diameter smaller than the inward surface 64a of the annular recess 64. As shown in Fig. 4, the foam member 90 is composed of a foam core layer 86 having a large number of pores 86a and a solid skin layer 87 without pores 86a that surrounds the foam core layer 86. The foam core layer 86 preferably has a closed-cell structure in which the individual pores 86a are independent so as to continuously generate stable rigidity as the foam member 90, but may also have an open-cell structure in which some adjacent pores 86a are connected to each other.

[0026] The foam member 90 can be manufactured by a foam injection molding method or a foam extrusion molding method using a foamable resin material. Examples of resins include various thermoplastic resins, specifically, polyolefins such as high-pressure low-density polyethylene, which is a homopolymer or copolymer of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene, linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), polypropylene (propylene homopolymer), propylene random copolymer, propylene block copolymer, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene random copolymer, ethylene-1-butene random copolymer, and propylene-1-butene random copolymer, polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (nylon-6, nylon-66, polymetaxylene adipamide, etc.), polyvinyl chloride, polyimide, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-acrylic acid ester-carbon monoxide copolymer, polyacrylonitrile-butadiene copolymer, and the like. Examples of suitable resins include those known as engineering plastics, such as nitrile, polycarbonate, polystyrene, ionomer, polyacetal, modified polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyetheretherketone, polyetherimide, and polyamideimide, as well as mixtures thereof. Among these, high-pressure low-density polyethylene, linear low-density polyethylene, high-density polyethylene, propylene-based polymers such as polypropylene and propylene random copolymers and propylene block copolymers, polyethylene terephthalate, polyamide, and engineering plastics are preferred. These thermoplastic resins may be used alone or in combination. However, because the solid skin layer 87 comes into contact with the working fluid 70, resins with low reactivity with the working fluid 70 are selected from these resins.

[0027] The foaming agent may be a chemical foaming agent or a physical foaming agent, and therefore may be a solvent-type foaming agent or a decomposition-type foaming agent, or may be a gaseous foaming agent such as nitrogen, carbon dioxide, argon, or air, or a thermal expansion type microcapsule foaming agent.

[0028] FIG. 5 is a schematic diagram illustrating the process for producing a foam member 90. As shown in FIG. 5( a), a base resin and a foaming agent are supplied from a hopper 96 to an injection molding machine 95, and the resulting mixed foaming-agent-containing resin material 99 is supplied and filled into the cavity of a mold 98 having a fixed mold 98A and a movable mold 98B. The foaming agent may be supplied separately into a cylinder 97. Next, as shown in FIG. 5( b), the movable mold 98B is cored back, the foaming agent is foamed, and the foaming-agent-containing resin material 99 in the cavity is solidified. This produces a foam member 90 having a foam core layer 86 with pores 86a formed therein and a solid skin layer 87 arranged around the foam core layer 86.

[0029] Furthermore, the foam member 90 may be formed by using rubber or a thermoplastic elastomer instead of resin as the base material, adding a foaming agent, and molding by injection, extrusion, press, etc. The foam member 90 may also be formed from a foamed metal material, as long as it has the same function. In this case, the metal material is preferably one that is highly durable and can continuously provide stable rigidity.

[0030] In addition, the foam member 90 may be manufactured by foaming a foam material inside an enclosed space formed by a housing having any shape, such as a cube, a rectangular parallelepiped, a sphere, a semicircular arc, or a ring. Furthermore, the foam member 90 may be manufactured by foaming a foam material inside an enclosed space, and then covering the outer surface of the solid skin layer 87 or the surface of a cut-out portion of the foam core layer 86 with a separately provided cover member 102 (see FIG. 6 ). The cover member may be configured to cover the entire foamed foam material as is, or may be configured to cover an arbitrarily cut-out portion of the foam material. The cover member provided separately from the foamed foam material may be made of any material that is impermeable to the working fluid 70.

[0031] 7( a), the foam member 90 includes a small-diameter ring 87A and a large-diameter ring 87B that are concentrically arranged to form a solid skin layer 87, and a foam core layer 86 that fills the space between the small-diameter ring 87A and the large-diameter ring 87B. Alternatively, the foam member 90 may further include a pair of annular plates 88 that close openings on both axial sides of the small-diameter ring 87A and the large-diameter ring 87B, as shown in FIG.

[0032] Here, the foam core layer 86 is formed by injecting a mixture of a base material and a foaming agent into the annular space partitioned by the small-diameter ring 87A, the large-diameter ring 87B, and a pair of annular plates 88, filling the space, and then foaming the foaming agent to form a foam. In the case of Figure 7(a), foaming is suppressed near the annular plate 88, and the base material essentially forms the solid skin layer 87. Therefore, the annular plate 88 can be removed to form the foam member 90. Note that, if the small-diameter ring 87A and the large-diameter ring 87B are configured to be separate from the foam member 90, the foam member 90 may be constructed by separating all of the components that form the sealed space.

[0033] 8, at least one outer layer 101 may be provided that covers the entire peripheral surface of the foam member 90 with a molded member. This allows the rigidity of the foam member 90 to be changed and also protects the surface of the foam member 90 from the working fluid 70. Note that the foam member 90 referred to here may be formed from any of the above-mentioned materials or by any of the above-mentioned molding methods, and includes foam members molded by an injection molding machine, foam members in which the components that constitute the sealed space are separated, foam members in which the components that constitute the sealed space are used as the foam member 90, and the like.

[0034] In the above embodiment, the foam member 90 is molded seamlessly as a single piece, which makes it difficult for localized stress concentrations to occur and allows for easy manufacturing. However, the foam member 90 is not limited to being molded as a single piece, and may be, for example, a combined body having a foamed cross section, which is formed by joining the end faces of two or more members to integrate these two or more members.

[0035] For example, as shown in Figure 9, divided pieces 90c1 to 90c4 of the foam member can be made into an arc shape, and their end faces can be connected to form a single annular foam member 90. By using a divided structure like this, the molding die 98 (see Figure 5) can be made smaller, making manufacturing easier. The connection method can be selected from among an appropriate adhesive, heat fusion, or a mechanical locking mechanism.

[0036] In the above embodiment, the foam member 90 has a rectangular or circular cross section, but is not limited thereto. It may have an elliptical cross section as shown in Fig. 10(a) or a triangular cross section as shown in Fig. 10(b), and may be formed into any other shape. Furthermore, in this embodiment, the foam member 90 is not limited to an annular shape and may be formed of one or more foam members having any shape, such as a cube, a rectangular parallelepiped, a sphere, or a semicircular arc. For example, as shown in Fig. 10(c), multiple foam members 90 may be disposed within the pressure chamber 66. Additionally, the peripheral surface of such a foam member having any shape, such as a cube, a rectangular parallelepiped, a sphere, or a semicircular arc, may be covered with the outer layer described above.

[0037] 10(d), a hollow member 100 can be mixed in the pressure chamber 66 together with the foam member 90. The hollow member 100 is made of elastically deformable rubber, resin, metal, etc., or a combination of these, and the hollow member 100 contains any liquid or gas that has an elastic effect when an external force is applied and whose rigidity has been industrially confirmed.

[0038] In this embodiment, oil is used as the working fluid 70, but this is not limited thereto, and any liquid or gas, including water, that has an elastic effect when an external force is applied and whose rigidity has been industrially confirmed may be used. Regarding the elastic effect of the working fluid, reference is made to, for example, a non-patent document (Deshimaru Junichi and Tanaka Hirohisa, "Measurement of the Bulk Modulus of Hydraulic Oil," Hydraulics and Pneumatics, Vol. 19, No. 7, pp. 580-583) which describes that the bulk modulus of hydraulic oil is affected by the inclusion of gas.

[0039] Furthermore, O-rings 67 are fitted between the outward surface 65a of the annular convex portion 65 and the inward surface 64a of the annular recessed portion 64, and between the inward surface 65b of the annular convex portion 65 and the outward surface 64b of the annular recessed portion 64. Specifically, the O-rings 67 are arranged in annular seal grooves 68 formed on the outward surface 65a and the inward surface 65b of the annular convex portion 65 and come into sliding contact with the opposing inward surface 64a and the outward surface 64b of the annular recessed portion 64 to seal the radial gap between the outward surface 65a of the annular convex portion 65 and the inward surface 64a of the annular recessed portion 64, and the radial gap between the inward surface 65b of the annular convex portion 65 and the outward surface 64b of the annular recessed portion 64. Note that the seal grooves 68 may also be formed on the inward surface 64a and the outward surface 64b of the annular recessed portion 64. Furthermore, one O-ring 67 and one seal groove 68 are respectively arranged between the opposing surfaces, but multiple O-rings 67 and multiple seal grooves 68 may also be arranged. As a result, the O-ring 67 prevents leakage of the working fluid 70 filled in the pressure chamber 66. From the viewpoint of preventing wear, the O-ring 67 may be subjected to a surface treatment that provides wear resistance or the like.

[0040] An anti-rotation mechanism 75 is provided between the support base side member 61 and the bearing housing side member 62 to prevent relative rotation therebetween. Specifically, for example, the bearing housing side member 62 has a through-hole 77 formed in at least one location in the circumferential direction, which penetrates radially so that the tip of a positioning pin 76 protrudes from the inward surface 64a of the annular recess 64. The tip of the positioning pin 76 is inserted into an elongated hole 78 formed along the axial direction in the outward surface 65a of the annular protrusion 65 of the support base side member 61 so that the bearing housing side member 62 can move in the axial direction. Note that the positioning pin 76 may be replaced by a rotational positioning key (not shown) having a similar anti-rotation function, which is inserted into the elongated hole 78 so that the bearing housing side member 62 can move in the axial direction.

[0041] In this housing position adjustment mechanism 60, the foamed member 90 is placed in the pressure chamber 66, the working fluid 70 is filled, and then the fastening nut 38b is tightened to press the bearing housing side member 62 toward the support base side member 61 via the pair of angular ball bearings 53, 53 and the moving-side bearing housing 51. As a result, the foamed member 90 in the pressure chamber 66 is compressed by the working fluid 70, and pressure in the screw axial direction is applied to the working fluid 70.

[0042] On the other hand, since the support base side member 61 is fixed to the base 1 via the support base 43, the bearing housing side member 62 and the movable side bearing housing 51 are pressed to the left in the figure via the working fluid 70 by the pressure of the compressed foam member 90 arranged in the pressure chamber 66. This brings about a state in which tension is applied to the screw shaft 21 in advance to the left in Figures 1 and 2.

[0043] The pressure of the foaming material 90 disposed in the pressure chamber 66 can be controlled to any desired magnitude by adjusting the tightening amount of the fastening nut 38b. That is, the magnitude of the axial load applied to the screw shaft 21 by the fastening nut 38b can be set to any desired magnitude. Furthermore, the magnitude of the axial load applied to the screw shaft 21 by the working fluid 70 and the foaming material 90 may be set by taking into account, in addition to being set by the tightening amount of the fastening nut 38b, volume changes of the working fluid 70 and the foaming material 90 caused by temperature increases of the angular contact ball bearings 53 and the screw shaft 21 during operation of the ball screw feed device 20. Additionally, the magnitude of the axial load applied to the screw shaft 21 by the working fluid 70 and the foaming material 90 may be set by taking into account volume changes of the working fluid 70 and the foaming material 90 caused by temperature increases of the working fluid 70 and the foaming material 90 due to environmental changes around the ball screw feed device 20 during operation of the ball screw feed device 20.

[0044] Next, we will explain the operation of the ball screw feed device 20 of this embodiment. In the ball screw feed device 20, when the screw shaft 21 is rotationally driven by the drive motor 12 and the moving table 11 fixed to the nut 23 is caused to move linearly back and forth, the drive motor 12, angular contact ball bearings 33, 53, nut 23, etc. generate heat in association with this movement, the temperature of the ball screw feed device 20 gradually rises, and the screw shaft 21 extends in the axial direction due to thermal expansion.

[0045] 1, when the screw shaft 21 expands in the axial direction due to thermal expansion, it extends leftward because the right end of the screw shaft 21 is fixed to the fixed-side bearing housing 31 via the angular contact ball bearings 33, 33. When the screw shaft 21 expands in the axial direction (leftward) due to the influence of heat, the bearing unit 41 and the bearing housing side member 62 move in the same direction, following the axial expansion of the screw shaft 21 due to thermal expansion, while maintaining a state in which they are pressed by the pressure of the foamed member 90 disposed in the pressure chamber 66 via the working fluid 70.

[0046] In this embodiment, the foam member 90 is designed to continue to press the bearing unit 41 and the bearing housing side member 62 to the left via the working fluid 70, even when the screw shaft 21 extends in the axial direction. The foam member 90 and the pressure chamber 66 have a high degree of design freedom, and by appropriately selecting the physical properties of the working fluid filled in the pressure chamber and the size and shape of the pressure chamber, it is possible to apply a sufficient and appropriate load to accommodate greater axial extension compared to when a disc spring or the like is used. Therefore, even if the temperature of the ball screw feed device 20 rises above 4 degrees, the pair of angular contact ball bearings 53, 53 can be moved axially to maintain axial support rigidity, and the axial rigidity of the ball screw feed device 20 is stabilized.

[0047] In particular, the pressure exerted by the foaming material 90 can change in accordance with the axial elongation of the screw shaft 21 even when the temperature rises by more than 4 degrees, so that while the screw shaft 21 is elongating in the axial direction, the axial rigidity of the ball screw feed device 20 is stabilized while maintaining the pair of angular ball bearings 33, 33 as fixed support parts.

[0048] In this case, an excessive load is not applied to the pair of angular ball bearings 33, 33 and 53, 53, so there is no risk of excessive wear or seizure due to poor lubrication, and the life of the pair of angular ball bearings 33, 33 and 53, 53 is extended. That is, in this embodiment, it is no longer necessary to apply to the screw shaft 21 a pretension of the magnitude that is applied by the spacer in the ball screw described in Patent Document 1, so an excessive load is not applied to the pair of angular ball bearings 33, 33 and 53, 53 either.

[0049] Furthermore, in the ball screw feed device 20 of this embodiment, it is not necessary to install an external device for supplying the working fluid 70 to the pressure chamber 66, and the housing position adjustment mechanism 60 can be simplified. As a result, the pressure in the pressure chamber 66 can be maintained with as little change as possible without consuming energy supplied from the outside. Note that the ball screw feed device 20 of this embodiment may be configured to be provided with an external device such as an accumulator or a pump.

[0050] The O-ring 67 in this embodiment also functions as a damping mechanism. That is, when a workpiece placed on the movable table 11 is machined, vibrations generated in the movable table 11 tend to vibrate the screw shaft 21, which has a relatively low rigidity. The vibrations of the screw shaft 21 are propagated to the bearing housing side member 62 via the pair of angular contact ball bearings 33 and the movable-side bearing housing 51. However, the O-ring 67 between the bearing housing side member 62 and the support base side member 61 damps the vibrations of the bearing housing side member 62. Therefore, the vibrations of the screw shaft 21 can also be damped, suppressing disturbances in the quality of the machined surface of the workpiece placed on the movable table 11. In this case, the O-ring 67 disposed between the bearing housing side member 62 and the support base side member 61 damps not only the axial vibrations of the screw shaft 21 but also the radial vibrations of the screw shaft 21.

[0051] Furthermore, the working fluid 70 of the housing position adjustment mechanism 60 is stored not only in the pressure chamber 66, but also in the gaps between the outward surface 65 a of the annular convex portion 65 and the inward surface 64 a of the annular recessed portion 64, and between the inward surface 65 b of the annular convex portion 65 and the outward surface 64 b of the annular recessed portion 64, and in each gap on the pressure chamber 66 side of the O-ring 67. Therefore, the pressure of the foamed member 90 is transmitted via the working fluid 70, and the bearing housing side member 62 is supported with a sufficient and appropriate radial load against the support base side member 61. As a result, the housing position adjustment mechanism 60 can provide radial support rigidity to the screw shaft 21 via the pair of angular contact ball bearings 53, 53 and the bearing housing 51, and can also have an aligning function for the screw shaft 21.

[0052] 11 , the tip surface of the annular convex portion 65 of the support base side member 61 may be formed in a pointed convex tapered shape from the inner peripheral edge to the outer peripheral edge so that the axial length of the pressure chamber 66 gradually increases radially outward. This allows the bearing housing side member 62 to be more aligned with the support base side member 61 when the foamed member 90 is accommodated in the pressure chamber 66 and the pressure chamber 66 is filled with the working fluid 70, thereby further improving the alignment function of the pair of angular contact ball bearings 53, 53 with the screw shaft 21.

[0053] Although not shown, if the tip surface of the annular protrusion 65 of the support base side member 61 has a convex tapered shape from the outer circumferential edge to the inner circumferential edge, the coaxiality of the pair of angular ball bearings 53, 53 with respect to the screw shaft 21 can be improved. Also, although not shown, the support base side member 61 may be configured integrally with the support base 43, and the bearing housing side member 62 may also be configured integrally with the moving-side bearing housing 51.

[0054] Second Embodiment Next, a ball screw feed device according to a second embodiment of the present invention will be described with reference to Figures 12 and 13. Note that in this embodiment, the configuration of the housing position adjustment mechanism 60 of the second support mechanism 40 is different from that of the first embodiment.

[0055] In the housing position adjustment mechanism 60 of the second embodiment, multiple (three in this embodiment) foam members 90 are disposed within the pressure chamber 66. In this embodiment, all three foam members 90 are formed in an annular shape and are disposed concentrically with different outer diameters. The foam members 90 do not need to be made of the same material; appropriate rigidity can be imparted depending on their shape and physical properties. Furthermore, the multiple foam members 90 do not necessarily need to be disposed in a regular, concentric manner or be annular, but each is configured to have a seamless, sealed structure that can generate pressure when compressed.

[0056] As shown in Fig. 13, each foamed member 90 is deformed and compressed in accordance with the amount of axial tightening of the fastening nut 38b. Meanwhile, the bearing housing side member 62 and the moving-side bearing housing 51 are pressed via the working fluid 70 by the force generated in the thread axial direction by the multiple foamed members 90 in a compressed state. At this time, the amount of axial tightening can be made larger due to the effect of elastic deformation of the other foamed members 90 than when a single foamed member 90 generates the same axial force, as shown in Fig. 13.

[0057] Therefore, similar to the first embodiment, even if the temperature of the ball screw feed device 20 rises above 4 degrees, the multiple foamed members 90 function in combination to move the pair of angular contact ball bearings 53, 53 in the axial direction, thereby maintaining the axial support rigidity and stabilizing the axial rigidity of the ball screw feed device 20. Furthermore, by using multiple foamed members 90, it is possible to obtain large deformation even with the same compressive load, and it is also possible to avoid complete loss of function due to destruction of the member itself caused by plastic deformation, which is a concern when using only a single foamed member. The other configurations and operations are the same as those of the first embodiment.

[0058] Third Embodiment Next, a ball screw feed device according to a third embodiment of the present invention will be described with reference to Fig. 14. Note that in this embodiment, the configuration of the housing position adjustment mechanism 60 of the second support mechanism 40 is different from that of the first embodiment.

[0059] In the housing position adjustment mechanism 60 of the third embodiment, a storage chamber 71 is formed within the annular convex portion 65, and an orifice 72 is formed along the axial direction at at least one location in the circumferential direction (two locations in Figure 14) to connect the storage chamber 71 to the pressure chamber 66.

[0060] The reservoir chamber 71 is formed in a disk groove shape, opening onto the outward surface 65 a of the annular protrusion 65 closer to the tip surface of the annular protrusion 65 than the groove in which the O-ring 67 is disposed. Therefore, in this embodiment, the working fluid 70 is stored not only in the pressure chamber 66 but also in the reservoir chamber 71 and the orifice 72.

[0061] As a result, in this embodiment, vibration of the screw shaft 21 causes the bearing housing side member 62 to vibrate together with the moving-side bearing housing 51 and the pair of angular contact ball bearings 33, 33, and the working fluid 70 in the pressure chamber 66 and the reservoir chamber 71 passes through the orifice 72 and the gap g between the outward surface 65 a of the annular convex portion 65 and the inward surface 64 a of the annular concave portion 64, thereby damping the vibration. Therefore, similar to the O-ring 67 described above, when a workpiece placed on the moving table 11 is machined, the vibration transmitted to the screw shaft 21 can be damped, further improving the quality of the machined surface of the workpiece.

[0062] In the above embodiment, the reservoir chamber 71 is formed on the outer diameter side so as to open to the outward surface 65a of the annular convex portion 65, but it may also be formed on the inner diameter side so as to open to the inward surface 65b of the annular convex portion 65. The cross-sectional shape and length of the orifice 72 may be arbitrarily formed as long as they provide a damping function. The other configurations and functions are the same as those of the first embodiment.

[0063] Fourth Embodiment Next, a ball screw feed device according to a fourth embodiment of the present invention will be described with reference to Figures 15 and 16. Note that in this embodiment, the configuration of the housing position adjustment mechanism 60 of the second support mechanism 40 is different from that of the first embodiment.

[0064] In the housing position adjustment mechanism 60 of the fourth embodiment, the seal groove 68 formed on the outward surface 65a and the inward surface 65b of the annular convex portion 65 is composed of a tapered surface 69a whose groove depth becomes shallower as it moves away from the pressure chamber 66 side, and circular ring-shaped axial side surfaces 69b, 69c extending radially from both axial end edges of the tapered surface 69a.

[0065] Furthermore, the axial distance between the axial side surfaces 69b, 69c is wider than the axial width of the O-ring 67 when it is elastically deformed and attached to the seal groove 68. As a result, the working fluid 70 that has passed through the gap g from the pressure chamber 66 flows around to the vicinity of the boundary between the axial side surface 69b, which has a deeper groove, and the tapered surface 69a.

[0066] Therefore, as the pressure of the working fluid 70 in the pressure chamber 66 increases and the O-ring 67 is pushed toward the atmospheric pressure side by the working fluid 70, the O-ring 67 further improves the sealing performance due to the wedge structure between the tapered surface 69a of the seal groove 68 and the inward surface 64a and outward surface 64b of the opposing annular recess 64. As a result, even if relative movement occurs between the support base side member 61 and the bearing housing side member 62, leakage of the working fluid 70 toward the atmospheric pressure side can be prevented, and the axial rigidity of the ball screw feed device 20 can be continuously maintained.

[0067] As a modification of this embodiment, as shown in Figures 17(a) to (c), a wear-resistant member 59 may be interposed between the O-ring 67 and at least one of the inward surface 64a of the annular recess 64 and the outward surface 65a of the annular protrusion 65 (in this embodiment, the tapered surface 69a of the seal groove 68 formed on the outward surface 65a).

[0068] Specifically, as shown in FIG. 17( a), the wear-resistant member 59 may be formed as an annular member with a U-shaped cross section so as to be positioned between the outer peripheral surface of the O-ring 67 and the inward surface 64 a of the annular recess 64, and between the inner peripheral surface of the O-ring 67 and the tapered surface 69 a of the seal groove 68 formed on the outward surface 65 a of the annular protrusion 65.

[0069] 17(b), the wear-resistant member 59 may be formed as an annular member having a straight cross section so as to be positioned between the inner peripheral surface of the O-ring 67 and the tapered surface 69a of the seal groove 68 formed in the outward surface 65a of the annular convex portion 65. Furthermore, as shown in Fig. 17(c), the wear-resistant member 59 may be formed as an annular member having a straight cross section so as to be positioned between the outer peripheral surface of the O-ring 67 and the inward surface 64a of the annular recess 64.

[0070] The wear-resistant member 59 may be made of, for example, a resin material such as a fluorine-based resin, or a metal material that has been subjected to an appropriate surface treatment.

[0071] In any of the embodiments shown in Figures 17(a) to (c), the use of the wear-resistant member 59 can disperse the stress concentration on the O-ring 67, thereby suppressing damage such as wear to the O-ring 67 and the contact surface with the O-ring 67.

[0072] In addition, the wear-resistant member 59 may also be interposed between the O-ring 67 and at least one of the outward surface 64b of the annular recess 64 and the inward surface 65b of the annular protrusion 65 (in FIG. 16, the tapered surface 69a of the seal groove 68 formed on the inward surface 65b), as shown in FIG.

[0073] 17(a) to 17(c), the wear-resistant member 59 is interposed between the O-ring 67 and the opposing surface of the O-ring 67 in the seal groove 68 having a tapered surface 69a. On the other hand, the above effect can also be achieved by interposing the wear-resistant member 59 between the O-ring 67 and the opposing surface of the O-ring 67 in the seal groove 68 having a uniform groove depth as shown in Fig. 2. The other configurations and operations are the same as those of the first embodiment.

[0074] Fifth Embodiment Next, a ball screw feed device according to a fifth embodiment of the present invention will be described with reference to Fig. 18. Note that in this embodiment, the configuration of the housing position adjustment mechanism 60 of the second support mechanism 40 is different from that of the first embodiment.

[0075] In the housing position adjustment mechanism 60 of the fifth embodiment, heating elements 80, 81, such as heating wires or rubber heaters, serving as working medium volume change parts, are arranged in a ring shape or discretely on the outer circumferential surfaces of the support base side member 61 and the bearing housing side member 62.

[0076] As a result, heat from the heating elements 80, 81 is transferred from the support base side member 61 and the bearing housing side member 62 to the foamed material 90 and the working fluid 70 in the pressure chamber 66, heating the foamed material 90 and the working fluid 70, thereby expanding the volumes of the foamed material 90 and the working fluid 70. As a result, even if the screw shaft 21 extends in the axial direction, a load is excited in the pressure chamber 66 due to the volumetric expansion of the foamed material 90 and the working fluid 70, so that the support rigidity in the axial direction can be maintained.

[0077] In this embodiment, heating elements 80, 81 are attached to the outer peripheral surfaces of the support base side member 61 and the bearing housing side member 62 as working medium volume change units, but cooling media 82, 83 such as a cooling jacket or a cooling element may be attached instead.

[0078] By using the cooling media 82, 83, even if the load excited in the pressure chamber 66 becomes excessive due to the volume expansion of the foamed member 90 and the working fluid 70, it is possible to cool the foamed member 90 and the working fluid 70 and contract the volumes of the foamed member 90 and the working fluid 70. This prevents the axial support stiffness of the ball screw feed device 20 from becoming excessively large, and makes it possible to continuously maintain the axial support stiffness in a stable state.

[0079] In addition, in this embodiment, the temperatures of the foamed member 90 and the working fluid 70 are affected by the components, installation environment, operating cycle, etc. of the ball screw feed device 20, and therefore the foamed member 90 and the working fluid 70 may be controlled to a target temperature by forming a feedback loop for the temperatures of the components, the foamed member 90, the working fluid 70, etc. using the heating elements 80, 81 and the cooling media 82, 83. Furthermore, in this embodiment, the operation of the heating elements 80, 81 and the cooling media 82, 83 may be feedback-controlled by taking into consideration the volume change of the working fluid 70, the pressure state within the pressure chamber 66, the relative axial displacement between the support base side member 61 and the bearing housing side member 62, etc.

[0080] In addition, in this embodiment, the working medium volume change unit is attached to both the support base side member 61 and the bearing housing side member 62, but it may also be attached to either the support base side member 61 or the bearing housing side member 62.

[0081] Furthermore, in this embodiment, the working fluid volume change unit is provided on the outer peripheral surface of the support base side member 61 and the outer peripheral surface of the bearing housing side member 62, but it can be attached to any location, such as the axial side surface, inner peripheral surface, or interior, as long as it can expand or contract the volume of the foaming member 90 and working fluid 70 in the pressure chamber 66. In addition, a heating element may be attached to one of the support base side member 61 and the bearing housing side member 62, and a cooling medium may be attached to the other. Furthermore, the heating element and the cooling medium may be arranged so as to coexist in either the support base side member 61 or the bearing housing side member 62. The other configurations and operations are the same as those of the first embodiment.

[0082] Sixth Embodiment Next, a ball screw feed device according to a sixth embodiment of the present invention will be described with reference to Fig. 19. Note that this embodiment differs from the first embodiment in that the second support mechanism 40 further includes another housing position adjustment mechanism 160.

[0083] That is, the second support mechanism 40 of the sixth embodiment further includes another housing position adjustment mechanism 160 disposed adjacent to the housing position adjustment mechanism 60 between the bearing unit 41 and the support base 43. The other housing position adjustment mechanism 160 includes: another support base side member 161 provided on the support base 43 side and through which the screw shaft 21 passes; another bearing housing side member 162 provided on the bearing housing 51 side and through which the screw shaft 21 passes and which is movable in the axial direction relative to the other support base side member 161; a foamed member 90 disposed in a pressure chamber 166 formed between the other support base side member 161 and the other bearing housing side member 162; and another working fluid 170 filled in the space within the pressure chamber 166 other than the foamed member 90. That is, the second support mechanism 40 includes two housing position adjustment mechanisms 60, 160 arranged in tandem in series in the axial direction.

[0084] 19 , in the other housing position adjustment mechanism 160, the other bearing housing side member 162 has an annular recess 164, and the other support base side member 161 has an annular protrusion 165 that fits axially slidably within the annular recess 164, and the foaming member 90 and the other working fluid 170 are disposed in a pressure chamber 166 formed between the annular recess 164 and the annular protrusion 165. As the other working fluid 170, the one exemplified as the working fluid 70 is applied.

[0085] In this embodiment, the other support base side member 161 has an annular portion 161a protruding toward the support base 43 and fitted into a through hole 43a of the support base 43, and is fixed to the support base 43 with a plurality of bolts (not shown). Furthermore, the support base side member 61 of the housing position adjustment mechanism 60 and the other bearing housing side member 162 of the other housing position adjustment mechanism 160 are integrally configured as a single member or by connecting the two.

[0086] In this way, by arranging the two housing position adjustment mechanisms 60, 160 in series in the axial direction, it is possible to stably maintain the axial rigidity of the ball screw feed device 20 even when the extension of the screw shaft is even greater, and it is also possible to improve axial alignment and coaxiality.

[0087] The other housing position adjustment mechanism 160 is not limited to the same configuration as the housing position adjustment mechanism 60 shown in FIG. 19 , and may have any other configuration as long as it has a pressure generating means housed in a compressed state in a pressure chamber 166 formed between the other support base side member 161 and the other bearing housing side member 162. For example, a resilient member such as a spring may be disposed in the pressure chamber 166 as the pressure generating means. Furthermore, the second support mechanism 40 may have two housing position adjustment mechanisms 60, 160, or may have three or more housing position adjustment mechanisms, as long as the multiple housing position adjustment mechanisms are arranged in series in the axial direction. The other configurations and operations are the same as those of the first embodiment.

[0088] In the first to sixth embodiments, the pair of angular contact ball bearings used in the bearing unit of the second support mechanism are arranged in a face-to-face configuration, but the arrangement is not limited to this. That is, the pair of angular contact ball bearings 53, 53 may be arranged in various support configurations, such as a back-to-back configuration as shown in FIG. 20 or a parallel configuration as shown in FIG. 21 . When the pair of angular contact ball bearings 53, 53 are arranged in a back-to-back configuration as shown in FIG. 20 , an inner ring spacer 49 may be disposed between the step between the large-diameter portion 24 and the small-diameter portion 25 of the screw shaft 21 and the inner ring 55 of the angular contact ball bearing 53 on the axially inner side. Furthermore, while the pair of angular contact ball bearings 33, 33 of the first support mechanism are also arranged in a face-to-face configuration, they may be arranged in various support configurations, such as a back-to-face configuration or a parallel configuration. Furthermore, although not shown, the angular contact ball bearings 33, 53 do not necessarily have to be composed of two angular contact ball bearings, but may be composed of three or more angular contact ball bearings.

[0089] Furthermore, in the above embodiment, the other housing position adjustment mechanism 160 is disposed adjacent to the housing position adjustment mechanism 60 in the axial direction, but this is not limiting, and the other housing position adjustment mechanism 160 may be disposed adjacent to the housing position adjustment mechanism 60 in the radial direction in parallel. This makes it easier to maintain the axial rigidity of the ball screw feed device 20 while suppressing the axial dimension of the ball screw feed device 20 and in a state where a larger axial load is generated than when a single housing position adjustment mechanism is disposed.

[0090] In the above embodiment, the pressure chamber 66 is formed in an annular shape by the annular recess 64 and the annular protrusion 65. However, multiple recesses and protrusions may be formed in the circumferential direction to form multiple pressure chambers. In this case, an O-ring may be placed between the inner peripheral surface of the recess and the outer peripheral surface of the protrusion to provide a leakage and damping function for the working fluid. Alternatively, a storage chamber opening onto the outer peripheral surface of the protrusion and an orifice communicating the storage chamber with the pressure chamber may be provided to provide an additional damping function. In this case, a foamed member designed in an appropriate shape, such as a sphere or a rectangular parallelepiped, may be used.

[0091] For example, as shown in FIG. 22( a), four pressure chambers 66 may be arranged around the screw shaft 21 in the circumferential direction, or as shown in FIG. 22( b), two pressure chambers 66 arranged side by side and adjacent to each other in the radial direction may be arranged at four circumferential positions, i.e., a total of eight pressure chambers 66 may be arranged around the screw shaft 21. Alternatively, as shown in FIG. 23( a), two pressure chambers 66 may be arranged around the screw shaft 21 in the circumferential direction, i.e., the pressure chambers 66 on both sides in the width direction (Y direction) of the screw shaft 21. Or, as shown in FIG. 23( b), three pressure chambers 66 arranged side by side and adjacent to each other in the radial direction (width direction in this example) may be arranged at two circumferential positions, i.e., a total of six pressure chambers 66 may be arranged around the screw shaft 21. In this case, the height dimensions of the support base side member 61 and the bearing housing side member 62 can be reduced.

[0092] 24, two pressure chambers 66 may be arranged around the screw shaft 21, i.e., pressure chambers 66 on both the upper and lower sides of the screw shaft 21. In this case, the width dimensions of the support base side member 61 and the bearing housing side member 62 can be reduced.

[0093] 25 is a schematic cross-sectional view taken along line XXV-XXV in FIG. 23(a). In this case, the two pressure chambers 66 are each formed of a recess 64x and a protrusion 65x. In the drawing, the protrusion 65x is formed integrally with the base of the support base member 61, but it may also be formed separately from the base and then joined.

[0094] The multiple pressure chambers 66 can be arranged arbitrarily as long as the bearing unit 41 and the bearing housing side member 62 can move stably in the same direction following the axial extension of the screw shaft 21 due to thermal expansion, and specifically, they are preferably arranged point-symmetrically or line-symmetrically on a plane perpendicular to the screw shaft 21. The multiple pressure chambers 66 may also be arranged offset in the axial direction.

[0095] Furthermore, adjacent pressure chambers 66 may be communicated with each other via a communication passage as necessary for the purpose of equalizing pressure, and the working fluid inside may flow through adjacent pressure chambers 66. For example, in Figures 23(b) and 24, adjacent pressure chambers 66 are communicated with each other via a communication passage 66x.

[0096] Furthermore, the support base side member 61 and the bearing housing side member 62 are not limited to being formed as a single member, but may be divided and arranged around the screw shaft 21 according to the layout of the pressure chamber 66. Furthermore, the support base side member 61 and the bearing housing side member 62, which are single members, may also be formed with a portion of the circumferential direction open or divided and arranged around the screw shaft 21. For example, in Figure 23 (b), two support base side members 61 and two bearing housing side members 62 are divided in the width direction of the screw shaft 21.

[0097] In addition, similar to the other housing position adjustment mechanisms 160 described above, the pressure generating means in the multiple pressure chambers 66 are not limited to all having the same configuration, i.e., foam material and working fluid filled in a compressed state, but the pressure generating means in any of the pressure chambers 66 may have other configurations, such as using only working fluid or an elastic member such as a spring.

[0098] Furthermore, the recesses and protrusions that make up the pressure chambers 66 are not limited to being circular in cross section, but may be any shape, such as rectangular. Furthermore, the cross-sectional dimensions and axial dimensions of the multiple pressure chambers 66 can each be configured as desired.

[0099] Seventh Embodiment In the housing position adjustment mechanism 60 of the above-described embodiment and modified example, when the screw shaft 21 extends in the axial direction, the volume of the pressure chamber 66 increases, and the compressed foam member 90 gradually reduces its pressure while pressing the bearing unit 41 and the bearing housing side member 62 to the left via the working fluid 70. This causes the pair of angular contact ball bearings 53 to move axially, maintaining the axial support rigidity of the screw shaft 21.

[0100] However, in the seventh embodiment, the axial support rigidity of the screw shaft 21 is maintained by using a housing position adjustment mechanism 60 as shown in FIG. 26 . Specifically, when the screw shaft 21 expands in the axial direction, the bearing unit 41 and the bearing housing side member 62 move to the left via the pair of angular contact ball bearings 53, 53 that move together with the screw shaft 21, and the volume of the pressure chamber 66 decreases. Meanwhile, as the pressure in the foamed member 90 gradually increases, the bearing unit 41 and the bearing housing side member 62 are pressed to the right via the working fluid 70. Therefore, by adjusting the volume of the pressure chamber 66 and the pressure in the foamed member 90 so as to allow the screw shaft 21 to expand in the axial direction, the axial support rigidity of the screw shaft 21 can be maintained.

[0101] In this case, the support base side member 61 has a small-diameter cylindrical portion 61c extending from the small-diameter portion of the annular base portion 61b attached to the support base 43 toward the bearing housing 51, and an outward flange portion 61d extending from the tip of the small-diameter cylindrical portion 61c toward the outer diameter side. The bearing housing side member 62 has a large-diameter cylindrical portion 62c extending from the large-diameter portion of the annular base portion 62b attached to the moving-side bearing housing 51 toward the support base 43, and an inward flange portion 62d extending from the tip of the large-diameter cylindrical portion 62c toward the inner diameter side.

[0102] The outward flange portion 61d of the support base side member 61 is relatively movable in the axial direction between the annular base portion 62b and the inward flange portion 62d of the bearing housing side member 62, and its outer peripheral surface is in sliding contact with the inner peripheral surface of the large-diameter cylindrical portion 62c via an O-ring 67. Furthermore, the inward flange portion 62d of the bearing housing side member 62 is relatively movable in the axial direction between the annular base portion 61b and the outward flange portion 61d of the support base side member 61, and its inner peripheral surface is in sliding contact with the outer peripheral surface of the small-diameter cylindrical portion 61c via the O-ring 67. Therefore, the pressure chamber 66 is formed by an annular space partitioned by the small-diameter cylindrical portion 61c and the outward flange portion 61d of the support base side member 61 and the large-diameter cylindrical portion 62c and the inward flange portion 62d of the bearing housing side member 62, and this pressure chamber 66 contains the foaming member 90 together with the working fluid 70.

[0103] In this case, too, the size and material of the foaming member 90 are appropriately selected so that even if the temperature rises by more than 4 degrees, the working fluid 70 and the foaming member 90 are compressed when the pressure chamber 66 narrows in the axial direction in accordance with the axial elongation of the screw shaft 21, and the pressure acting on the bearing housing side member 62 gives the screw shaft 21 the desired axial rigidity.

[0104] In addition, by installing the O-ring 67 between the inner surface of the inward flange portion 62d and the outer surface of the small diameter cylindrical portion 61c, and between the outer surface of the outward flange portion 61d and the inner surface of the large diameter cylindrical portion 62c, leakage of the working fluid 70 filled in the pressure chamber 66 can be prevented, and the O-ring 67 also functions as a damping mechanism to damp vibrations occurring in the screw shaft 21.

[0105] Furthermore, working fluid 70 is stored in each gap between the inner circumferential surface of the inward flange portion 62d and the outer circumferential surface of the small-diameter cylindrical portion 61c, and between the outer circumferential surface of the outward flange portion 61d and the inner circumferential surface of the large-diameter cylindrical portion 62c. Therefore, the radial pressure of the working fluid 70 acting on each gap can increase the radial support rigidity and alignment ability between the bearing housing side member 62 and the support base side member 61. As a result, the housing position adjustment mechanism 60 can provide radial support rigidity to the screw shaft 21 and can also have an alignment function for the screw shaft 21.

[0106] The support base side member 61 and the bearing housing side member 62 may each be formed from a single member, but in consideration of ease of assembly, they may each be formed with an O-ring 67 sandwiched between two members 91, 92, 93, 94, as shown in Figure 26. Also, one O-ring 67 and one seal groove 68 are disposed between each opposing surface, but multiple O-rings 67 and multiple seal grooves 68 may be disposed.

[0107] Also, instead of Figure 26, the support base side member 61 may have a large diameter cylindrical portion and an inward flange portion, and the bearing housing side member 62 may have a small diameter cylindrical portion and an outward flange portion to form a pressure chamber.

[0108] 27, such a housing position adjustment mechanism 60 may be provided with a storage chamber 71 and an orifice 72 in the outward flange portion 61d, and similarly to the second embodiment, the working fluid 70 in the pressure chamber 66 and the storage chamber 71 may pass through the orifice 72 and the gap between the inner circumferential surface of the large-diameter cylindrical portion 62c and the outer circumferential surface of the outward flange portion 61d, thereby providing a function of damping vibration of the screw shaft 21. Note that the storage chamber and the orifice may be formed in the inward flange portion 62d, and the storage chamber may be open to the outer circumferential surface of the small-diameter cylindrical portion 61c.

[0109] In addition, as in the modified example of the first embodiment, the axial side surface of the outward flange portion 61d or the inward flange portion 62d that forms the pressure chamber 66 may be formed into a convex tapered or concave tapered shape to enhance the aligning function or coaxiality of the angular ball bearings 53, 53 with the screw shaft 21.

[0110] Also in such a housing position adjustment mechanism 60, the pair of angular contact ball bearings 53, 53 may be arranged in a face-to-face configuration as shown in Figures 26 and 27, or in a back-to-back configuration as shown in Figure 28, or may be arranged in various other supporting configurations such as a parallel configuration. In addition, although not shown, the pair of angular contact ball bearings does not necessarily have to be made up of two angular contact ball bearings, but may also be made up of three or more ball bearings.

[0111] Furthermore, as shown in Figures 29 and 30, in the housing position adjustment mechanism 60 of the seventh embodiment, as in the fourth embodiment, the seal groove 68 formed on the inner surface of the inward flange portion 62d and the outer surface of the outward flange portion 61d may be composed of a tapered surface 69a whose groove depth becomes shallower as it moves away from the pressure chamber side, and circular axial side surfaces 69b, 69c extending radially from both axial end edges of the tapered surface 69a.

[0112] Therefore, as the pressure of the working fluid 70 in the pressure chamber 66 increases and the O-ring 67 is pushed toward the atmospheric pressure side, the O-ring 67 further improves the sealing performance due to the wedge structure between the tapered surface 69a of the seal groove 68 and the outer peripheral surface of the opposing small-diameter cylindrical portion 61c and the inner peripheral surface of the opposing large-diameter cylindrical portion 62c. As a result, even if relative movement occurs between the support base side member 61 and the bearing housing side member 62, leakage of the working fluid 70 toward the atmospheric pressure side can be prevented, and the axial rigidity of the ball screw feed device 20 can be continuously maintained.

[0113] In this modified example, as shown in Figure 30, the seal groove 68 formed on either of the opposing surfaces of the two members 91, 92 that make up the support base side member 61, and the seal groove 68 formed on either of the opposing surfaces of the two members 93, 94 that make up the bearing housing side member 62 may also have a tapered surface 69a in which the groove depth becomes shallower as it moves away from the pressure chamber side.

[0114] Also, in this modified example, a wear-resistant member may be interposed between the O-ring 67 and at least one of the inner surface of the inward flange portion 62d and the outer surface of the small-diameter cylindrical portion 61c, and between the O-ring 67 and at least one of the outer surface of the outward flange portion 61d and the inner surface of the large-diameter cylindrical portion 62c.

[0115] In this case, the wear-resistant member 59 may be interposed between the O-ring 67 and the opposing surface of the O-ring 67 in a seal groove 68 having a tapered surface 69a as shown in Figure 30, or may be interposed between the O-ring 67 and the opposing surface of the O-ring 67 in a seal groove 68 having a uniform groove depth as shown in Figure 26.

[0116] Furthermore, as shown in Figure 31, the housing position adjustment mechanism 60 of the seventh embodiment may be configured so that, similar to the fifth embodiment, the support base side member 61 and the bearing housing side member 62 are provided with working medium volume change units such as heating elements 80, 81 and cooling media 82, 83.

[0117] As a result, as described in the fifth embodiment, depending on the state of the ball screw feed device 20 being used, the volume of the foamed material 90 and working fluid 70 in the pressure chamber 66 can be expanded by the heating elements 80, 81, or the volume of the foamed material 90 and working fluid 70 in the pressure chamber 66 can be contracted by the cooling media 82, 83, thereby maintaining the axial support rigidity in a continuously stable state.

[0118] Furthermore, in the housing position adjustment mechanism 60 of the seventh embodiment, as shown in FIG. 32 , similar to the sixth embodiment, the second support mechanism 40 may have a tandem configuration in which the housing position adjustment mechanism 60 and another housing position adjustment mechanism 160 are arranged in series in the axial direction between the bearing unit 41 and the support base 43.

[0119] In this case, the other support base side member 161 of the other housing position adjustment mechanism 160 has an annular base portion 161b, a small-diameter cylindrical portion 161c, and an outward flange portion 161d, and the other bearing housing side member 162 has an annular base portion 162b, a large-diameter cylindrical portion 162c, and an inward flange portion 162d. The other support base side member 161 and the other bearing housing side member 162 of the other housing position adjustment mechanism 160 are each composed of two members 191, 192, 193, and 194. The support base side member 61 of the housing position adjustment mechanism 60 and the other bearing housing side member 162 of the other housing position adjustment mechanism 160 are connected to each other and configured as a single unit.

[0120] Furthermore, similar to the fifth embodiment, the second support mechanism 40 may be configured such that a plurality of housing position adjustment mechanisms are arranged in series in the axial direction, or may be configured such that they are arranged in parallel in the radial direction.

[0121] The present invention is not limited to the above-described embodiment, and modifications, improvements, etc. are possible as appropriate. Furthermore, the embodiments and modifications described in this specification can be combined within a practicable range. For example, the pressure chamber may diagnose and correct the condition of the ball screw feed device by monitoring the pressure of the working fluid or the load applied to the pair of angular contact ball bearings 53, 53.

[0122] Furthermore, in the first to sixth embodiments, O-rings 67 are fitted between the outward surface 65 a of the annular convex portion 65 and the inward surface 64 a of the annular recessed portion 64, and between the inward surface 65 b of the annular convex portion 65 and the outward surface 64 b of the annular recessed portion 64. However, this is not limited to this, and any seal members may be arranged to prevent leakage of the working fluid 70 from the pressure chamber 66. Similarly, in the seventh embodiment, O-rings 67 are fitted between the outer peripheral surface of the outward flange portion 61 d and the inner peripheral surface of the large-diameter cylindrical portion 62 c, and between the inner peripheral surface of the inward flange portion 62 d and the outer peripheral surface of the small-diameter cylindrical portion 61 c. However, this is not limited to this, and any seal members may be arranged to prevent leakage of the working fluid 70 from the pressure chamber 66. Furthermore, it is more preferable that the seal members not only prevent leakage of the working fluid 70 from the pressure chamber 66 but also damp vibrations of the screw shaft 21, similar to the O-ring 67.

[0123] Eighth Embodiment Next, a ball screw feed device according to an eighth embodiment of the present invention will be described with reference to Fig. 33. Note that in this embodiment, the configuration of the housing position adjustment mechanism 60 of the second support mechanism 40 differs from that of the first embodiment.

[0124] In this embodiment, the foam member 90 is fixed in an assembled state within the pressure chamber 66. Specifically, in the embodiment shown in Fig. 33, the foam member 90 is fixed so that the foam core layer 86 is in partial or full contact with the bottom surface, inward surface 64a, and outward surface 64b of the annular recess 64, and a solid skin layer 87 is provided on the surface of the foam member 90 that faces the tip surface of the annular protrusion 65, covering the surface of the foam core layer 86 facing the annular protrusion 65. Then, within the pressure chamber 66, the space between the solid skin layer 87, which is the facing surface of the foam member 90, and the tip surface of the annular protrusion 65 is filled with the working fluid 70.

[0125] In this embodiment, as in the above embodiment, even if the axial length of the screw shaft 21 changes due to the influence of heat, the action of the foamed member 90 and the working fluid 70 in the pressure chamber 66 can move the bearing unit 41 and the bearing housing side member 62, thereby maintaining the axial support rigidity, and stabilizing the axial rigidity of the ball screw feed device 20.

[0126] In this embodiment, the exposed surface of the foam core layer 86 is covered with the surface of the annular recess 64, while the opposing surface facing the tip surface of the annular protrusion 65 is formed by the solid skin layer 87 of the foam material 90. However, the opposing surface facing the tip surface of the annular protrusion 65 may be provided with a cover member provided separately from the foamed foam material, and the cover member may face the tip surface of the annular protrusion 65, i.e., face the working fluid 70.

[0127] Also in this embodiment, the foam member 90 may be configured such that the solid skin layer 87 partially covers the periphery of the foam core layer 86, or such that the solid skin layer 87 covers the entire periphery. Furthermore, when the foam member 90 is configured only with the foam core layer 86, it is sufficient that the surface of the periphery of the foam core layer 86 that faces the working fluid 70 is covered with a cover member. Therefore, in this embodiment, it is sufficient that at least a portion of the periphery of the foam core layer 86 is covered with at least one of the solid skin layer 87 and the cover member.

[0128] In any embodiment, the working fluid 70 needs to be sealed from the outside after being filled into the pressure chamber 66. In this case, for example, in the housing position adjustment mechanism 60 shown in Fig. 2, an oil supply passage 109 for filling the pressure chamber 66 with the working fluid 70 may be formed in the bearing housing side member 62, as shown in Fig. 34(a) , so as to penetrate radially between the inward surface 64a of the annular recess 64 and the outer peripheral surface of the bearing housing side member 62.

[0129] A stopper bolt 110 may be attached to the outer peripheral surface of the bearing housing side member 62, threadedly engaging with a female thread portion 109a formed in the oil supply passage 109 to close the oil supply passage 109. Furthermore, the male thread portion of the stopper bolt 110 may be wrapped with sealing tape (not shown) or coated or filled with a leak prevention agent, thereby filling the gap between the male thread and the female thread portion 109a, and thereby more reliably preventing leakage of the working fluid 70 filled in a compressed state.

[0130] An annular seal groove 110a may be formed in the surface of the head of the stopper bolt 110 that faces the outer circumferential surface of the bearing housing side member 62. An O-ring 111 may then be attached to the seal groove 110a to improve the sealing performance of the stopper bolt 110. As shown in Figure 34(b), the bottom surface of the seal groove 110a of the stopper bolt 110 may be tapered to further improve the sealing performance.

[0131] Furthermore, the member blocking the oil supply passage 109 may be a stopper plug instead of the stopper bolt 110. For example, the oil supply passage 109 may be blocked by a tapered stopper plug 112 as shown in FIG. 35( a). In this case, the stopper plug 112 is threaded into a female thread portion 109a formed on the outer diameter side of the oil supply passage 109 and fixed to the oil supply passage 109. Furthermore, as shown in FIG. 35( b), the oil supply passage 109 has a tapered female thread portion 109a on the outer diameter side, and a straight portion 109b without a female thread portion is continuous with the female thread portion 109a via a stepped hole 109c. In this case, the stopper plug 112 may be fastened to the female thread portion 109a with a disk-shaped member 113 accommodated in the stepped hole 109c. In this case, the stopper plug 112 is fastened to the female thread portion 109a while deforming the disk-shaped member 113, thereby ensuring a tight seal between the contact surface of the disk-shaped member 113 and the stepped hole 109c. In addition, the male thread portion of the stopper plug 112 may also be wrapped with sealing tape (not shown) or coated or filled with a leak prevention agent to fill the gap between the male thread and the female thread portion 109a, thereby providing a good seal.

[0132] As shown in Fig. 35(c), the disk-shaped member 113 may be integrated with an elastically deformable member 114 that forms the contact surface with the stepped hole 109c. Alternatively, as shown in Fig. 35(d), the disk-shaped member 113 may have an annular seal groove 113a formed in the contact surface with the stepped hole 109c, and an O-ring 115 may be disposed therein.

[0133] Furthermore, the oil supply passage 109 communicating with the pressure chamber 66 is not limited to a configuration in which it is formed so as to penetrate in the radial direction, but may be formed so as to penetrate in the axial direction through any of the members that constitute the pressure chamber 66 .

[0134] Furthermore, the support base may be configured to directly or indirectly support the support base side member of the housing position adjustment mechanism, and is not limited to a configuration in which the rotation axis passes through it as in the above embodiment, but may also be configured to be arranged around the rotation axis, and can be designed into any shape.

[0135] (Application to Other Ball Screw Feeding Devices) In the ball screw feeding device 20 of Fig. 1, the drive motor 12 is coupled to one side (the right side in Fig. 1) of the screw shaft 21 supported by the first support mechanism 30, but the present invention is not limited to this. That is, as in the ball screw feeding device 20 of Fig. 36, the drive motor 12 may be coupled to the other side (the left side in Fig. 36) of the screw shaft 21 supported by the second support mechanism 40. In this case, the drive motor 12 is fixed to the base 1 and supported by another support base 85 through which the screw shaft 21 passes. In addition, the tip of the small diameter shaft portion 27 is disposed within the coupling 28 away from the rotating shaft 12a of the drive motor 12 so that the small diameter shaft portion 27 can move in the axial direction when the screw shaft 21 expands axially due to thermal expansion.

[0136] Therefore, the present invention can be used with a high degree of freedom as a ball screw feed device for positioning devices that perform high-precision processing and measurement, such as machine tools (machining centers, lathes, grinding machines, etc.), measuring machines (three-dimensional measuring devices), semiconductor manufacturing equipment (tables for exposure devices, inspection probes, etc.), inspection equipment, etc., and for use in semiconductor manufacturing, etc.

[0137] Furthermore, in the above embodiment, the support base 43 is disposed on the axial center side relative to the bearing unit 41, but the present invention is not limited to this, and the support base 43 may be disposed on the axial end side relative to the bearing unit 41. That is, the support base 43 may be disposed on the axial center side relative to the bearing unit 41 or on the axial end side depending on the configuration and function of the housing position adjustment mechanism 60.

[0138] 37 and 38 , the support base 43 is provided closer to the axial end than the bearing unit 41. In this case, the support base side member 61 may be attached directly or indirectly to the support base 43, and the bearing housing side member 62 may be attached directly or indirectly to the bearing housing 51. In addition, the spacer 48a, which is disposed between the inner ring 55 and the fastening nut 38b, passes through the through hole 43a of the support base 43 and the inside of the support base side member 61 and the bearing housing side member 62.

[0139] 39 and 40 , the support base 43 is disposed closer to the axial end than the bearing unit 41, and is fixed to a support base side member 61 disposed closer to the axial center than the bearing unit 41 by an outer cylinder portion 43b that extends axially from a main body portion having a through hole 43a and surrounds the periphery of the housing position adjustment mechanism 60. In this case, too, the support base side member 61 may be attached directly or indirectly to the support base 43, and the bearing housing side member 62 may be attached directly or indirectly to the bearing housing 51. In addition, a spacer 48a disposed between the inner ring 55 and the fastening nut 38b passes through the through hole 43a of the support base 43.

[0140] (Applications Other Than Ball Screw Feeder Devices) Although the above-described embodiment describes a ball screw feeder device, the present invention can also be applied to a rotation support device in which both axial ends of a rotating shaft are rotatably supported by a pair of support mechanisms. That is, when the axial length of the rotating shaft changes due to the influence of heat, a configuration can be made in which the axial support rigidity of the rotating shaft is continuously and stably maintained using a housing position adjustment mechanism such as that of the above embodiment. Furthermore, by using the housing position adjustment mechanism of the above embodiment, vibrations in the axial direction can be damped.

[0141] 41, a rotation support device 120 includes a rotating shaft 121 and a pair of support mechanisms 30, 40 that rotatably support both axial ends of the rotating shaft 121. The support mechanism 30 includes a bearing housing 31 fixed to the base 1, and bearings 33, 33 that rotatably support the rotating shaft 121 relative to the bearing housing 31, i.e., a pair of angular contact ball bearings 33, 33 arranged in a face-to-face combination.

[0142] The support mechanism 40 also includes a bearing housing 51, a bearing unit 41 that supports the rotating shaft 121 rotatably relative to the bearing housing 51 and is equipped with bearings 53, 53 that can support axial loads, i.e., a pair of angular ball bearings 53, 53 arranged in a face-to-face combination, a support base 43 that is arranged axially toward the center of the bearing unit 41 and through which the rotating shaft 121 passes, and a housing position adjustment mechanism 60 that is arranged between the bearing unit 41 and the support base 43.

[0143] The housing position adjustment mechanism 60 includes a support base side member 61 provided on the support base 43 side and through which the rotating shaft 121 passes, a bearing housing side member 62 provided on the bearing housing 51 side and through which the rotating shaft 121 passes and which is movable in the axial direction relative to the support base side member 61, a foam member 90 disposed in a pressure chamber 66 formed between the support base side member 61 and the bearing housing side member 62, and a working fluid 70 filled in the space within the pressure chamber 66 other than the foam member 90. Note that in FIG. 41 , components with the same reference numerals as those in the above embodiment are considered to be substantially the same, and their description will be omitted or simplified. The various structures described in the ball screw feed device 20 can also be applied to the rotation support device, and similar effects will be achieved.

[0144] Furthermore, the bearings 33, 53 of the support mechanisms 30, 40 of the rotation support device 120 may be angular contact ball bearings as in the above embodiment, but are not limited to these and may also be roller bearings or plain bearings capable of supporting axial loads. By using such bearings capable of supporting axial loads, the foamed member 90 can be compressed via the bearings, particularly in the support mechanism 40, by tightening the fastening nut 38b as in the above embodiment.

[0145] In addition, in Figure 41, the second support mechanism 40 having the housing position adjustment mechanism 60 is configured to support the end of the rotating shaft 121, but as shown in Figure 42, the second support mechanism 40 having the housing position adjustment mechanism 60 may be configured to support the rotating shaft 121 at a position closer to another support base 85 that supports the drive motor 12.

[0146] For example, when a rotary support device 120 such as that shown in FIG. 42 is applied to a spindle device that rotates a tool in a machine tool, by attaching a tool to the end of the rotating shaft 121 supported by the support mechanism 30, the axial support rigidity of the rotating shaft 121 is continuously and stably maintained while the axial positioning of the tool is reliably performed, thereby enabling high-precision machining.

[0147] In the rotary support device 120 shown in Figures 41 and 42, the drive motor 12 does not necessarily have to be arranged coaxially with the rotating shaft 121, and the power of the drive motor may be transmitted to the rotating shaft 121 via, for example, a pulley or a gear train.

[0148] In addition, the drive motor 12 is not necessarily limited to a separate motor arranged coaxially with the rotation shaft 121, but may be a built-in motor directly configured on the rotation shaft 121, for example.

[0149] In addition, in rotation support devices other than the ball screw feed device, the support base may also be disposed on the axial end side of the bearing unit as shown in Figures 37 to 40. Furthermore, the rotation support device 120 may have a housing case as the support body, in which the bearing housing 31 of the first support mechanism 30 and the support base 43 of the second support mechanism 40 are integrated.

[0150] Furthermore, in the above embodiment, the housing position adjustment mechanism is described as a mechanism for adjusting the axial position of the bearing housing of the bearing that supports the rotating shaft, but the present invention is not limited to this and can be applied as a support mechanism position adjustment mechanism for a shaft support device. That is, the shaft is not limited to a rotating shaft, and the support mechanism is not limited to a configuration including a bearing. The shaft support device may be configured to include a shaft and a pair of support mechanisms provided at both axial ends of the shaft to support the shaft on a base, one of the pair of support mechanisms including a support body (e.g., support base 43 in the above embodiment) through which the shaft passes or around which the shaft is disposed.

[0151] Therefore, the support mechanism position adjustment mechanism of the shaft support device may be configured to include a first member (e.g., support base member 61 in the above embodiment) provided on either the shaft side or the support side, through which the shaft passes or which can be arranged around the shaft, a second member (e.g., bearing housing member 62 in the above embodiment) provided on the other of the shaft side or the support side, through which the shaft passes or which can be arranged around the shaft, movable axially relative to the first member, and which forms an accommodation space (e.g., pressure chamber 66 in the above embodiment) between the first member and the second member, a foamed member disposed in the accommodation space, and a working fluid filled in the space other than the foamed member in the accommodation space. The support mechanism position adjustment mechanism of such a shaft support device can be configured to include the housing position adjustment mechanism described in connection with the ball screw feed device 20, and achieves similar effects.

[0152] 43 and 44 show a rigid-jointed structure 200 as a shaft support device in which a support mechanism position adjustment mechanism is provided on one of a pair of support mechanisms that support a shaft. The rigid-jointed structure 200 includes two parallel steel supports 231, 243 that are fixed vertically to a base 1. Concentric through-holes 231a, 243a are formed in the supports 231, 243, and a shaft 221 that constitutes a beam member is inserted through these through-holes. The supports 231, 243 may be pillars, beams, support plates, or the like, and may be made of any material and shape that can support a shaft.

[0153] In this example, the flange portion 226 on one axial end of the shaft 221 abuts against the small diameter step portion 231b of the through hole 231a of the support body 231, and one end of the shaft 221 is positioned and fixed to the support body 231 by the other support mechanism that attaches the pressing lid 232 to the large diameter step portion 231c of the through hole 231a.

[0154] The other axial end of shaft 221 passes through a through-hole 243a of support 243, protrudes to the opposite side from support 231, and is supported by support 243 via a shaft guide member 250, a housing 251, and a support mechanism position adjustment mechanism 260, which constitute one of the support mechanisms. The cross-sectional shape of the central part of shaft 221 is arbitrary, and may be made of a square steel pipe, an H-shaped steel, or the like.

[0155] The shaft guide member 250 is a member configured to surround the shaft 221, guides the small diameter portion 225 of the shaft 221, and has both outer diameter ends sandwiched and integrated between the housing 251 and a pressing member 247 fixed to the housing 251.

[0156] As in the above embodiment, the housing 251 is attached to the support body 243 via a support mechanism position adjustment mechanism 260. That is, a first member 261 corresponding to the support base side member 61 in the above embodiment is fitted into a through hole 243a of the support body 243 and fixed to the support body 243, and a second member 262 corresponding to the bearing housing side member 62 in the above embodiment is fitted into an inward flange 251a of the housing 251 and fixed to the housing 251.

[0157] Therefore, when the shaft guide member 250 is tightened by the fastening nut 38b that is threaded onto the male screw 225a via the spacer 48, a reaction force acts on the shaft guide member 250, and the shaft guide member 250 is subjected to an axial load. Therefore, a predetermined rigidity is provided between the supports 231, 243 and the shaft 221.

[0158] Furthermore, in such a rigid-jointed structure 200, even if axial elongation occurs in the shaft 221, the support mechanism position adjustment mechanism 260 operates to move the shaft guide member 250 and the housing 251 in the same direction in response to the axial elongation of the shaft 221. Therefore, the axial force acting on the shaft 221 can be maintained, and the rigidity of the rigid-jointed structure 200 can be maintained.

[0159] In this example, the housing 251 and the second member 262 of the support mechanism position adjustment mechanism 260 may be integrally configured, and the shaft guide member 250 may be disposed on the integrated member. Alternatively, the housing 251 may be omitted, and the shaft guide member 250 may be directly fixed to the second member 262 of the support mechanism position adjustment mechanism 260. The shaft support device is not limited to a rigid joint structure as in this example, and may have a brace structure in which the support mechanisms on the shaft side and the support body side are pin-jointed. In this case, the shaft 221 may be disposed at an angle depending on the configuration of the brace structure. Furthermore, in a shaft support device such as a rigid structure, both support mechanisms may have a support mechanism position adjustment mechanism.

[0160] As described above, the present specification discloses the following: (1) A rotary support device comprising a rotating shaft and a pair of support mechanisms rotatably supporting both axial ends of the rotating shaft, one of the pair of support mechanisms comprising: a bearing unit comprising a bearing housing and a bearing rotatably supporting the rotating shaft relative to the bearing housing and capable of supporting an axial load; a support base through which the rotating shaft passes or which is arranged around the rotating shaft; and a housing position adjustment mechanism arranged between the bearing unit and the support base, wherein the housing position adjustment mechanism comprises: a support base side member provided on the support base side and through which the rotating shaft passes or which is arranged around the rotating shaft; a bearing housing side member provided on the bearing housing side and through which the rotating shaft passes or which is arranged around the rotating shaft and is movable axially relative to the support base side member; a foam member disposed in a pressure chamber formed between the support base side member and the bearing housing side member, the foam member having a foam core layer and at least one of a solid skin layer and a cover member covering at least a portion of the periphery of the foam core layer; and a working fluid filled in the space in the pressure chamber other than the foam member. A rotary support device comprising: a foamed member that is disposed within a pressure chamber, and a pressure chamber that is disposed within the pressure chamber, which is configured to accommodate a rotating shaft;

[0161] (2) The rotation support device according to (1), wherein a plurality of the foam members are disposed within the pressure chamber. With this configuration, the total pressure generated by the foam members can continuously and stably maintain axial support rigidity even if the axial length of the rotating shaft changes due to the influence of heat.

[0162] (3) The rotation support device according to (1) or (2), wherein one of the support base member and the bearing housing member has an annular recess that opens to one axial side, and the other of the support base member and the bearing housing member has an annular protrusion that protrudes toward the other axial side and is axially slidably fitted within the annular recess, and the pressure chamber is formed between the annular recess and the annular protrusion. With this configuration, a foam member is disposed and the pressure chamber filled with the working fluid can be configured compactly around the rotation shaft.

[0163] (4) The rotation support device according to (3), wherein at least one seal member that prevents leakage of the working fluid filled in the pressure chamber is attached between the inward surface of the annular recess and the outward surface of the annular protrusion, and between the outward surface of the annular recess and the inward surface of the annular protrusion, respectively. With this configuration, the seal member can prevent leakage of the working fluid filled in the pressure chamber, and the function of the housing position adjustment mechanism can be maintained for a long period of time.

[0164] (5) The rotation support device according to (3) or (4), wherein the working fluid is stored in each gap between the inward surface of the annular recess and the outward surface of the annular protrusion, and between the outward surface of the annular recess and the inward surface of the annular protrusion. With this configuration, the housing position adjustment mechanism can provide radial support rigidity to the rotating shaft and can also have an alignment function with respect to the rotating shaft.

[0165] (6) The rotation support device according to (3) or (4), wherein the housing position adjustment mechanism includes: a reservoir chamber formed in the annular convex portion so as to open to an outward or inward surface of the annular convex portion and configured to store the working fluid; and an orifice formed in the annular convex portion so as to communicate the reservoir chamber with the pressure chamber. With this configuration, the working fluid in the pressure chamber and the reservoir chamber passes through the orifice and the gap between the outward surface of the annular convex portion and the inward surface of the annular recess, thereby damping the vibration.

[0166] (7) The rotation support device according to (3) or (4), wherein the tip end surface of the annular convex portion is formed in a convex tapered or concave tapered shape from its inner peripheral edge to its outer peripheral edge. This configuration can further improve the aligning function and coaxiality of the angular contact ball bearing with respect to the rotating shaft.

[0167] (8) The rotation support device according to (4), wherein the seal member is an O-ring, and a seal groove in which the O-ring is disposed is formed on the inward surface of the annular recess or the outward surface of the annular protrusion, and on the outward surface of the annular recess or the inward surface of the annular protrusion, respectively, and the seal groove has a tapered surface whose groove depth decreases with increasing distance from the pressure chamber. With this configuration, by using an O-ring as the seal member, the O-ring also functions as a damping mechanism, damping vibrations occurring in the rotating shaft. Furthermore, even when relative movement occurs between the support base member and the bearing housing member, leakage of hydraulic oil to the atmospheric pressure side can be prevented, thereby continuously maintaining the axial rigidity of the rotation support device.

[0168] (9) The rotation support device according to (4) or (8), wherein the sealing member is an O-ring, and a wear-resistant member is interposed between the O-ring and at least one of the inward surface of the annular recess and the outward surface of the annular protrusion, and between the O-ring and at least one of the outward surface of the annular recess and the inward surface of the annular protrusion. According to this configuration, by using the O-ring as the sealing member, the O-ring also functions as a damping mechanism, damping vibrations generated in the rotating shaft. Furthermore, stress concentration on the O-ring can be dispersed, suppressing damage such as wear to the O-ring and the contact surface with the O-ring.

[0169] (10) The rotation support device according to (1) or (2), wherein one of the support base member and the bearing housing member has a small-diameter cylindrical portion extending toward one axial direction and an outward flange portion extending from a tip of the small-diameter cylindrical portion toward an outer diameter side, and the other of the support base member and the bearing housing member has a large-diameter cylindrical portion extending toward the other axial direction and having an inner circumferential surface with which the outer circumferential surface of the outward flange portion slides, and an inward flange portion extending from a tip of the large-diameter cylindrical portion toward an inner diameter side and having an inner circumferential surface with which the outer circumferential surface of the small-diameter cylindrical portion slides, and the pressure chamber is formed in an annular space partitioned by the small-diameter cylindrical portion, the outward flange portion, the large-diameter cylindrical portion, and the inward flange portion. With this configuration, it is possible to continuously and stably maintain axial support rigidity even if the axial length of the rotating shaft changes due to the influence of heat.

[0170] (11) The rotation support device according to (10), wherein at least one seal member for preventing leakage of the working fluid filled in the pressure chamber is attached between the inner peripheral surface of the inward flange portion and the outer peripheral surface of the small-diameter cylindrical portion, and between the outer peripheral surface of the outward flange portion and the inner peripheral surface of the large-diameter cylindrical portion, respectively. With this configuration, the seal member can prevent leakage of the working fluid filled in the pressure chamber, and the function of the housing position adjustment mechanism can be maintained for a long period of time.

[0171] (12) The rotation support device according to (10) or (11), wherein the working fluid is stored in each gap between the inner peripheral surface of the inward flange portion and the outer peripheral surface of the small-diameter cylindrical portion, and between the outer peripheral surface of the outward flange portion and the inner peripheral surface of the large-diameter cylindrical portion. With this configuration, the housing position adjustment mechanism can provide radial support rigidity to the rotating shaft and can also have an alignment function with respect to the rotating shaft.

[0172] (13) The rotation support device according to (10) or (11), wherein the housing position adjustment mechanism includes: a reservoir chamber formed in the outward flange portion or the inward flange portion so as to open to an inner circumferential surface of the large-diameter cylindrical portion or an outer circumferential surface of the small-diameter cylindrical portion, for storing the working fluid; and an orifice formed in the outward flange portion or the inward flange portion so as to communicate the reservoir chamber with the pressure chamber. With this configuration, the working fluid in the pressure chamber and the reservoir chamber passes through the orifice and a gap between the inner circumferential surface of the large-diameter cylindrical portion and the outer circumferential surface of the outward flange portion, or between the outer circumferential surface of the small-diameter cylindrical portion and the inner circumferential surface of the inward flange portion, thereby damping the vibration.

[0173] (14) The rotation support device according to (11), wherein the seal member is an O-ring, and a seal groove in which the O-ring is disposed is formed on the inner circumferential surface of the inward flange portion or the outer circumferential surface of the small-diameter cylindrical portion, and on the outer circumferential surface of the outward flange portion or the inner circumferential surface of the large-diameter cylindrical portion, and the seal groove has a tapered surface whose groove depth decreases with increasing distance from the pressure chamber. With this configuration, by using an O-ring as the seal member, the O-ring also functions as a damping mechanism, damping vibrations occurring in the rotating shaft. Furthermore, even when relative movement occurs between the support base side member and the bearing housing side member, leakage of hydraulic oil to the atmospheric pressure side can be prevented, thereby continuously maintaining the axial rigidity of the rotation support device.

[0174] (15) The rotation support device according to (11), wherein the sealing member is an O-ring, and a wear-resistant member is interposed between the O-ring and at least one of the inner circumferential surface of the inward flange portion and the outer circumferential surface of the small-diameter cylindrical portion, and between the O-ring and at least one of the outer circumferential surface of the outward flange portion and the inner circumferential surface of the large-diameter cylindrical portion. With this configuration, the O-ring serves as a damping mechanism to attenuate vibrations occurring in the rotating shaft. Furthermore, stress concentration on the O-ring can be dispersed, suppressing damage such as wear to the O-ring and the contact surface with the O-ring.

[0175] (16) A rotation support device according to any one of (1) to (15), wherein a working fluid volume change unit is attached to at least one of the support base member and the bearing housing member, and changes the volume of the foamed member and the working fluid by heating or cooling the foamed member and the working fluid. With this configuration, the foamed member and the working fluid can be heated or cooled to expand or contract the volume of the foamed member and the working fluid, thereby maintaining a stable axial support rigidity.

[0176] (17) The rotary support device according to any one of (1) to (16), wherein one of the pair of support mechanisms further includes another housing position adjustment mechanism arranged adjacent to the housing position adjustment mechanism in series or parallel between the bearing unit and the support base, the other housing position adjustment mechanism including: another support base side member provided on the support base side and through which the rotation shaft passes or around which the rotation shaft is arranged; another bearing housing side member provided on the bearing housing side and through which the rotation shaft passes or around which the rotation shaft is arranged, and which is movable axially relative to the other support base side member; and pressure generating means accommodated in a compressed state in a pressure chamber formed between the other support base side member and the other bearing housing side member. With this configuration, in the case of a series arrangement, the axial rigidity of the rotary support device can be maintained even when the extension of the rotation shaft is greater, and the alignment and coaxiality of the rotation shaft can be improved. Furthermore, in the case of a parallel arrangement, a larger axial load can be generated and axial rigidity can be maintained compared to when a single housing position adjustment mechanism is arranged.

[0177] (18) The rotation support device according to (1), wherein one of the support base side member and the bearing housing side member has a plurality of recesses that open to one axial side, and the other of the support base side member and the bearing housing side member has a plurality of protrusions that protrude toward the other axial side and are axially slidably fitted within the plurality of recesses, and the plurality of pressure chambers are formed between the plurality of recesses and the plurality of protrusions. With this configuration, the layout of the housing position adjustment mechanism can be freely configured using the plurality of pressure chambers.

[0178] (19) The rotation support device according to (18), wherein the plurality of pressure chambers are arranged on both sides of the rotation shaft in the width direction. With this configuration, the height dimension of the housing position adjustment mechanism can be reduced.

[0179] (20) The rotation support device according to (18), wherein the foaming member and the working fluid are respectively disposed in the plurality of pressure chambers. With this configuration, the plurality of pressure chambers can be configured in common.

[0180] (21) The rotation support device according to any one of (1) to (20), wherein the bearing of the bearing unit includes a pair of angular contact ball bearings each including an outer ring fitted inside the bearing housing, an inner ring fitted externally onto an axial end of the rotating shaft, and balls disposed so as to roll between the outer ring and the inner ring. With this configuration, when the bearing unit has a pair of angular contact ball bearings, it is possible to continuously and stably maintain axial support rigidity even if the axial length of the rotating shaft changes due to the influence of heat.

[0181] (22) The rotation support device is a ball screw feed device according to any one of (1) to (21), further comprising: a screw shaft having a spiral thread groove formed on its outer circumferential surface as the rotation shaft; a nut having a spiral thread groove formed on its inner circumferential surface; and a plurality of balls disposed so as to roll between the thread groove of the screw shaft and the thread groove of the nut. With this configuration, it is possible to configure a ball screw feed device that can continuously and stably maintain axial support rigidity even if the axial length of the rotation shaft changes due to the influence of heat.

[0182] (23) A shaft support device including a shaft and a pair of support mechanisms provided at both axial ends of the shaft to support the shaft, comprising: a support mechanism position adjustment mechanism for the shaft support device provided on one of the pair of support mechanisms, wherein one of the pair of support mechanisms has a support through which the shaft passes or is arranged around the shaft, the support mechanism comprising: a first member provided on one of the shaft side and the support side, through which the shaft can pass or which can be arranged around the axis; a second member provided on the other of the shaft side and the support side, through which the shaft can pass or which can be arranged around the axis, movable axially relative to the first member, and forming an accommodation space between itself and the first member; a foam member provided in the accommodation space, having a foam core layer and at least one of a solid skin layer and a cover member covering at least a portion of the periphery of the foam core layer; and a working fluid filling the space within the accommodation space other than the foam member. With this configuration, it is possible to continuously and stably maintain axial support rigidity even if the axial length of the shaft changes due to the influence of heat. Furthermore, since the foaming member is disposed within the pressure chamber, it is not necessary to have an external accumulator or pump, and a compact configuration can be achieved.

[0183] (24) The support mechanism position adjustment mechanism for a shaft support device described in (23), wherein the shaft is a rotating shaft, one of the pair of support mechanisms further includes a bearing unit including a bearing housing and a bearing that rotatably supports the rotating shaft relative to the bearing housing and is capable of supporting an axial load, the support mechanism position adjustment mechanism is a housing position adjustment mechanism disposed between the bearing unit and the support, the first member is a support-side member provided on the support side and through which the rotating shaft can pass or which can be arranged around the rotating shaft, and the second member is a bearing-housing-side member provided on the bearing housing side and through which the rotating shaft can pass or which can be arranged around the rotating shaft, movable in the axial direction relative to the support-side member, and which forms the accommodation space between itself and the support-side member. With this configuration, it is possible to continuously and stably maintain axial support rigidity even if the axial length of the rotating shaft changes due to the influence of heat.

[0184] (25) The support mechanism position adjustment mechanism for a shaft support device according to (23) or (24), wherein a plurality of the foam members are disposed within the pressure chamber. With this configuration, the total pressure generated by the plurality of foam members makes it possible to continuously and stably maintain axial support rigidity even if the axial length of the shaft changes due to the influence of heat.

[0185] (26) A support mechanism position adjustment mechanism for a shaft support device according to any one of (23) to (25), wherein one of the first member and the second member has an annular recessed portion that opens to one axial side, and the other of the first member and the second member has an annular protruding portion that protrudes toward the other axial side and is fitted within the annular recessed portion so as to be slidable in the axial direction, and the pressure chamber is formed between the annular recessed portion and the annular protruding portion. With this configuration, a foamed member is disposed and a pressure chamber filled with a working fluid can be configured compactly around the shaft.

[0186] (27) A support mechanism position adjustment mechanism for a shaft support device according to (26), wherein at least one seal member that prevents leakage of the working fluid filled in the pressure chamber is attached between the inward surface of the annular recess and the outward surface of the annular protrusion, and between the outward surface of the annular recess and the inward surface of the annular protrusion, respectively. With this configuration, the seal member can prevent leakage of the working fluid filled in the pressure chamber, and the function of the support mechanism position adjustment mechanism can be maintained for a long period of time.

[0187] (28) A support mechanism position adjustment mechanism for a shaft support device according to (26) or (27), wherein the working fluid is stored in each gap between the inward surface of the annular recess and the outward surface of the annular protrusion, and between the outward surface of the annular recess and the inward surface of the annular protrusion. With this configuration, the support mechanism position adjustment mechanism can provide radial support rigidity to the shaft and can also have an aligning function with respect to the shaft.

[0188] (29) The support mechanism position adjustment mechanism for a shaft support device according to (26) or (27), wherein the support mechanism position adjustment mechanism comprises: a reservoir chamber formed in the annular convex portion so as to open to an outward or inward surface of the annular convex portion and configured to store the working fluid; and an orifice formed in the annular convex portion so as to communicate the reservoir chamber with the pressure chamber. With this configuration, the working fluid in the pressure chamber and the reservoir chamber passes through the orifice and the gap between the outward surface of the annular convex portion and the inward surface of the annular recess, thereby damping the vibration.

[0189] (30) The support mechanism position adjustment mechanism for a shaft support device according to (26) or (27), wherein the tip surface of the annular convex portion is formed in a convex tapered or concave tapered shape from its inner peripheral edge to its outer peripheral edge. With this configuration, the shaft alignment function and coaxiality can be further improved.

[0190] (31) The support mechanism position adjustment mechanism for a shaft support device described in (27), wherein the seal member is an O-ring, and a seal groove in which the O-ring is disposed is formed on the inward surface of the annular recess or the outward surface of the annular protrusion, and on the outward surface of the annular recess or the inward surface of the annular protrusion, respectively, and the seal groove has a tapered surface whose groove depth becomes shallower with increasing distance from the pressure chamber. With this configuration, by using an O-ring as the seal member, the O-ring also functions as a damping mechanism to damp vibrations occurring in the shaft. Furthermore, even if relative movement occurs between the first member and the second member, leakage of hydraulic oil to the atmospheric pressure side can be prevented, thereby continuously maintaining the axial rigidity of the shaft support device.

[0191] (32) The support mechanism position adjustment mechanism for a shaft support device according to (27) or (31), wherein the sealing member is an O-ring, and a wear-resistant member is interposed between the O-ring and at least one of the inward surface of the annular recess and the outward surface of the annular protrusion, and between the O-ring and at least one of the outward surface of the annular recess and the inward surface of the annular protrusion. With this configuration, by using an O-ring as the sealing member, the O-ring also functions as a damping mechanism, damping vibrations occurring in the shaft. Furthermore, stress concentration on the O-ring can be dispersed, suppressing damage such as wear to the O-ring and the contact surface with the O-ring.

[0192] (33) The support mechanism position adjustment mechanism for a shaft support device according to any one of (23) to (25), wherein one of the first member and the second member has a small-diameter cylindrical portion extending toward one side in the axial direction and an outward flange portion extending from a tip of the small-diameter cylindrical portion toward an outer diameter side, and the other of the first member and the second member has a large-diameter cylindrical portion extending toward the other side in the axial direction and having an inner circumferential surface with which the outer circumferential surface of the outward flange portion slides, and an inward flange portion extending from the tip of the large-diameter cylindrical portion toward an inner diameter side and having an inner circumferential surface that slides against the outer circumferential surface of the small-diameter cylindrical portion, and the pressure chamber is formed in an annular space partitioned by the small-diameter cylindrical portion, the outward flange portion, the large-diameter cylindrical portion, and the inward flange portion. With this configuration, axial support rigidity can be continuously and stably maintained even if the axial length of the shaft changes due to the influence of heat.

[0193] (34) A support mechanism position adjustment mechanism for a shaft support device according to (33), wherein at least one seal member that prevents leakage of the working fluid filled in the pressure chamber is attached between the inner peripheral surface of the inward flange portion and the outer peripheral surface of the small diameter cylindrical portion, and between the outer peripheral surface of the outward flange portion and the inner peripheral surface of the large diameter cylindrical portion. According to this configuration, the seal member can prevent leakage of the working fluid filled in the pressure chamber, and the function of the support mechanism position adjustment mechanism can be maintained for a long period of time.

[0194] (35) A support mechanism position adjustment mechanism for a shaft support device according to (33) or (34), wherein the working fluid is stored in each gap between the inner peripheral surface of the inward flange portion and the outer peripheral surface of the small diameter cylindrical portion, and between the outer peripheral surface of the outward flange portion and the inner peripheral surface of the large diameter cylindrical portion. With this configuration, the support mechanism position adjustment mechanism can provide radial support rigidity to the shaft and can also have an aligning function with respect to the shaft.

[0195] (36) The support mechanism position adjustment mechanism for a shaft support device according to (33) or (34), wherein the support mechanism position adjustment mechanism comprises: a reservoir chamber formed in the outward flange portion or the inward flange portion so as to open to the inner circumferential surface of the large-diameter cylindrical portion or the outer circumferential surface of the small-diameter cylindrical portion, for storing the working fluid; and an orifice formed in the outward flange portion or the inward flange portion so as to communicate the reservoir chamber with the pressure chamber. With this configuration, the working fluid in the pressure chamber and the reservoir chamber passes through the orifice and the gap between the inner circumferential surface of the large-diameter cylindrical portion and the outer circumferential surface of the outward flange portion, or between the outer circumferential surface of the small-diameter cylindrical portion and the inner circumferential surface of the inward flange portion, thereby damping the vibration.

[0196] (37) The support mechanism position adjustment mechanism for a shaft support device described in (34), wherein the seal member is an O-ring, and a seal groove in which the O-ring is disposed is formed on the inner circumferential surface of the inward flange portion or the outer circumferential surface of the small-diameter cylindrical portion, and on the outer circumferential surface of the outward flange portion or the inner circumferential surface of the large-diameter cylindrical portion, and the seal groove has a tapered surface whose groove depth decreases with increasing distance from the pressure chamber. With this configuration, by using an O-ring as the seal member, the O-ring also functions as a damping mechanism to damp vibrations occurring in the shaft. Furthermore, even if relative movement occurs between the first member and the second member, leakage of hydraulic oil to the atmospheric pressure side can be prevented, thereby continuously maintaining the axial rigidity of the shaft support device.

[0197] (38) The support mechanism position adjustment mechanism for a shaft support device according to (34), wherein the sealing member is an O-ring, and a wear-resistant member is interposed between the O-ring and at least one of the inner circumferential surface of the inward flange portion and the outer circumferential surface of the small-diameter cylindrical portion, and between the O-ring and at least one of the outer circumferential surface of the outward flange portion and the inner circumferential surface of the large-diameter cylindrical portion. With this configuration, by using an O-ring as the sealing member, the O-ring also functions as a damping mechanism, damping vibrations occurring in the shaft. Furthermore, stress concentration on the O-ring can be dispersed, suppressing damage such as wear to the O-ring and the contact surface with the O-ring.

[0198] (39) The support mechanism position adjustment mechanism for a shaft support device according to any one of (23) to (38), wherein a working fluid volume change unit that changes the volume of the foamed member and the working fluid by heating or cooling the foamed member and the working fluid is attached to at least one of the first member and the second member. With this configuration, the foamed member and the working fluid can be heated or cooled to expand or contract the volume of the foamed member and the working fluid, thereby maintaining a stable axial support rigidity.

[0199] (40) The support mechanism position adjustment mechanism for a shaft support device according to any one of (23) to (39), wherein one of the pair of support mechanisms further includes another support mechanism position adjustment mechanism arranged adjacent to the support mechanism position adjustment mechanism in series or parallel between the bearing unit and the support, the other support mechanism position adjustment mechanism including: an other first member provided on the support side and through which the shaft passes or around which the shaft is arranged; an other second member provided on the shaft side and through which the shaft passes or around which the shaft is arranged, and which is movable axially relative to the other first member; and pressure generating means accommodated in a compressed state in a pressure chamber formed between the other first member and the other second member. With this configuration, in the case of a series arrangement, the axial rigidity of the shaft support device can be maintained even when the shaft elongates even more, and the shaft alignment and coaxiality can be improved. Furthermore, in the case of a parallel arrangement, a larger axial load can be generated and axial rigidity can be maintained compared to when a single support mechanism position adjustment mechanism is arranged.

[0200] (41) A support mechanism position adjustment mechanism for a shaft support device according to (23), wherein one of the first member and the second member has a plurality of recesses that open to one axial side, and the other of the first member and the second member has a plurality of protrusions that protrude toward the other axial side and are fitted axially slidably within the plurality of recesses, and the plurality of pressure chambers are formed between the plurality of recesses and the plurality of protrusions, respectively. With this configuration, the layout of the support mechanism position adjustment mechanism can be freely configured using the plurality of pressure chambers.

[0201] (42) The support mechanism position adjustment mechanism for a shaft support device according to (41), wherein the plurality of pressure chambers are arranged on both sides of the shaft in the width direction. With this configuration, the height dimension of the support mechanism position adjustment mechanism can be reduced.

[0202] (43) The support mechanism position adjustment mechanism for a shaft support device according to (41), wherein the foaming member and the working fluid are respectively disposed in the plurality of pressure chambers. With this configuration, the plurality of pressure chambers can be configured in common.

[0203] This application is based on a Japanese patent application (Patent Application No. 2024-72741) filed on April 26, 2024, the contents of which are incorporated herein by reference.

[0204] DESCRIPTION OF SYMBOLS 20 Ball screw feed device (shaft support device, rotation support device) 21 Screw shaft (shaft, rotating shaft) 23 Nut 30 First support mechanism (support mechanism) 31 Fixed side bearing housing 33, 53 Angular contact ball bearing (bearing) 34, 54 Outer ring 35, 55 Inner ring 36, 56 Balls 38a, 38b Fastening nut 40 Second support mechanism (support mechanism) 41 Bearing unit 43 Support base (support member) 51 Moving side bearing housing (bearing housing) 51a Inward flange 59 Wear-resistant member 60 Housing position adjustment mechanism (support mechanism position adjustment mechanism) 61 Support base side member (first member) 62 Bearing housing side member (second member) 64 Annular recess 65 Annular protrusion 66 Pressure chamber (accommodation space) 67 O-ring (seal member) 68 Seal groove 69a Tapered surface 70 Working fluid 80, 81 Heat generating element (working fluid volume changer) 82, 83 Cooling medium (working fluid volume changer) 86 Foamed core layer 87 Solid skin layer 90 Foamed member 100 Hollow member 120 Rotation support device 121 Rotating shaft 160 Other housing position adjustment mechanism 161 Other support base side member (other support body side member) 162 Other bearing housing side member 170 Other working fluid

Claims

1. A rotary support device comprising a rotating shaft and a pair of support mechanisms rotatably supporting both axial ends of the rotating shaft, one of the pair of support mechanisms comprising: a bearing unit comprising a bearing housing and a bearing that rotatably supports the rotating shaft relative to the bearing housing and is capable of supporting an axial load; a support base through which the rotating shaft passes or around which it is arranged; and a housing position adjustment mechanism disposed between the bearing unit and the support base, wherein the housing position adjustment mechanism comprises: a support base side member provided on the support base side and through which the rotating shaft passes or around which it is arranged; a bearing housing side member provided on the bearing housing side and through which the rotating shaft passes or around which it is arranged, and which is movable axially relative to the support base side member; a foam member disposed in a pressure chamber formed between the support base side member and the bearing housing side member, the foam member having a foam core layer and at least one of a solid skin layer and a cover member covering at least a portion of the periphery of the foam core layer; and a working fluid filled in the space within the pressure chamber other than the foam member. A rotary support device comprising:

2. The rotation support device according to claim 1, wherein a plurality of said foam members are disposed within said pressure chamber.

3. A rotation support device as described in claim 1, wherein one of the support base side member and the bearing housing side member has an annular recess that opens to one axial side, and the other of the support base side member and the bearing housing side member has an annular protrusion that protrudes toward the other axial side and fits axially within the annular recess so as to be slidable in the axial direction, and the pressure chamber is formed between the annular recess and the annular protrusion.

4. A rotation support device as described in claim 3, wherein at least one seal member is fitted between the inward surface of the annular recess and the outward surface of the annular protrusion, and between the outward surface of the annular recess and the inward surface of the annular protrusion, to prevent leakage of the working fluid filled in the pressure chamber.

5. A rotation support device as described in claim 3 or 4, wherein the working fluid is stored in each gap between the inward surface of the annular recess and the outward surface of the annular protrusion, and between the outward surface of the annular recess and the inward surface of the annular protrusion.

6. A rotary support device as described in claim 3 or 4, wherein the housing position adjustment mechanism comprises: a reservoir chamber formed within the annular convex portion so as to open to the outward or inward surface of the annular convex portion and for storing the working fluid; and an orifice formed within the annular convex portion so as to connect the reservoir chamber to the pressure chamber.

7. A rotary support device according to claim 3 or 4, wherein the tip surface of the annular convex portion is formed in a convex or concave tapered shape from its inner peripheral edge to its outer peripheral edge.

8. A rotation support device as described in claim 4, wherein the sealing member is an O-ring, and a seal groove in which the O-ring is placed is formed on the inward surface of the annular recess or the outward surface of the annular protrusion, and on the outward surface of the annular recess or the inward surface of the annular protrusion, respectively, and the seal groove has a tapered surface whose groove depth becomes shallower with increasing distance from the pressure chamber side.

9. A rotation support device as described in claim 4, wherein the sealing member is an O-ring, and a wear-resistant member is interposed between the O-ring and at least one of the inward-facing surface of the annular recess and the outward-facing surface of the annular protrusion, and between the O-ring and at least one of the outward-facing surface of the annular recess and the inward-facing surface of the annular protrusion.

10. A rotational support device as described in claim 1, wherein one of the support base side member and the bearing housing side member has a small-diameter cylindrical portion extending to one axial side and an outward flange portion extending from the tip of the small-diameter cylindrical portion toward the outer diameter side, and the other of the support base side member and the bearing housing side member has a large-diameter cylindrical portion extending to the other axial side and having an inner circumferential surface with which the outer circumferential surface of the outward flange portion slides, and an inward flange portion extending from the tip of the large-diameter cylindrical portion toward the inner diameter side and having an inner circumferential surface that slides against the outer circumferential surface of the small-diameter cylindrical portion, and wherein the pressure chamber is formed in an annular space partitioned by the small-diameter cylindrical portion, the outward flange portion, the large-diameter cylindrical portion, and the inward flange portion.

11. A rotation support device as described in claim 10, wherein at least one seal member is installed between the inner peripheral surface of the inward flange portion and the outer peripheral surface of the small diameter cylindrical portion, and between the outer peripheral surface of the outward flange portion and the inner peripheral surface of the large diameter cylindrical portion, to prevent leakage of the working fluid filled in the pressure chamber.

12. A rotation support device as described in claim 10 or 11, wherein the working fluid is stored in each gap between the inner surface of the inward flange portion and the outer surface of the small diameter cylindrical portion, and between the outer surface of the outward flange portion and the inner surface of the large diameter cylindrical portion.

13. A rotary support device as described in claim 10 or 11, wherein the housing position adjustment mechanism comprises: a storage chamber formed within the outward flange portion or the inward flange portion so as to open onto the inner surface of the large diameter cylindrical portion or the outer surface of the small diameter cylindrical portion, for storing the working fluid; and an orifice formed within the outward flange portion or the inward flange portion so as to communicate the storage chamber with the pressure chamber.

14. A rotary support device as described in claim 11, wherein the sealing member is an O-ring, and a seal groove in which the O-ring is disposed is formed on the inner surface of the inward flange portion or the outer surface of the small diameter cylindrical portion, and on the outer surface of the outward flange portion or the inner surface of the large diameter cylindrical portion, and the seal groove has a tapered surface whose groove depth becomes shallower as it moves away from the pressure chamber side.

15. A rotation support device as described in claim 11, wherein the sealing member is an O-ring, and a wear-resistant member is interposed between the O-ring and at least one of the inner peripheral surface of the inward flange portion and the outer peripheral surface of the small-diameter cylindrical portion, and between the O-ring and at least one of the outer peripheral surface of the outward flange portion and the inner peripheral surface of the large-diameter cylindrical portion.

16. A rotary support device as described in claim 1, wherein a working medium volume change unit is attached to at least one of the support base side member and the bearing housing side member, which changes the volume of the foaming material and the working fluid by heating or cooling the foaming material and the working fluid.

17. A rotary support device as described in claim 1, wherein one of the pair of support mechanisms further comprises another housing position adjustment mechanism arranged adjacent to the housing position adjustment mechanism in series or parallel between the bearing unit and the support base, and the other housing position adjustment mechanism comprises: another support base side member provided on the support base side and through which the rotation shaft passes or which is arranged around the rotation shaft; another bearing housing side member provided on the bearing housing side and through which the rotation shaft passes or which is arranged around the rotation shaft and which is movable axially relative to the other support base side member; and pressure generating means contained in a compressed state in a pressure chamber formed between the other support base side member and the other bearing housing side member.

18. A rotation support device as described in claim 1, wherein one of the support base side member and the bearing housing side member has a plurality of recesses opening to one axial side, and the other of the support base side member and the bearing housing side member has a plurality of protrusions protruding toward the other axial side and fitting axially slidably within the plurality of recesses, and the plurality of pressure chambers are formed between the plurality of recesses and the plurality of protrusions, respectively.

19. A rotary support device according to claim 18, wherein the plurality of pressure chambers are arranged on both sides of the rotary shaft in the width direction.

20. The rotary support device according to claim 18, wherein the foam member and the working fluid are disposed in each of the plurality of pressure chambers.

21. A rotary support device as described in claim 1, wherein the bearing of the bearing unit includes a pair of angular contact ball bearings each having an outer ring fitted inside the bearing housing, an inner ring fitted outside the axial end of the rotating shaft, and balls arranged freely rollable between the outer ring and the inner ring.

22. The rotary support device according to claim 1, which is a ball screw feed device, further comprising: a rotating shaft which is a screw shaft having a spiral thread groove formed on its outer circumferential surface; a nut having a spiral thread groove formed on its inner circumferential surface; and a plurality of balls arranged so as to roll freely between the thread groove of the screw shaft and the thread groove of the nut.

23. A support mechanism position adjustment mechanism for a shaft support device comprising a shaft and a pair of support mechanisms provided at both axial ends of the shaft for supporting the shaft, the support mechanism position adjustment mechanism for the shaft support device being provided on one of the pair of support mechanisms, wherein one of the pair of support mechanisms has a support through which the shaft passes or which is arranged around the shaft; a first member provided on one of the shaft side and the support side, and through which the shaft can pass or which can be arranged around the axis; a second member provided on the other of the shaft side and the support side, and through which the shaft can pass or which can be arranged around the axis, movable axially relative to the first member, and forming an accommodation space between itself and the first member; a foam member provided within the accommodation space, and having a foam core layer and at least one of a solid skin layer and a cover member covering at least a portion of the periphery of the foam core layer; and a working fluid filled in the space within the accommodation space other than the foam member.

24. A support mechanism position adjustment mechanism for a shaft support device as described in claim 23, wherein the shaft is a rotating shaft, one of the pair of support mechanisms further comprises a bearing unit including a bearing housing and a bearing that rotatably supports the rotating shaft relative to the bearing housing and is capable of supporting an axial load, the support mechanism position adjustment mechanism is a housing position adjustment mechanism arranged between the bearing unit and the support, the first member is a support side member provided on the support side and through which the rotating shaft can pass or which can be arranged around the rotating shaft, and the second member is a bearing housing side member provided on the bearing housing side and through which the rotating shaft can pass or which can be arranged around the rotating shaft, which is movable axially relative to the support side member and forms the accommodation space between itself and the support side member.

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