Spindle unit of a machine tool

Abstract

To provide a spindle device for a machine tool that can rotate the spindle stably. [Solution] The spindle device comprises a spindle (21), a housing (50) that houses the spindle (21), a bearing (71) having an outer ring (76) and positioned between the spindle (21) and the housing (50) in the radial direction of the spindle (21), and an anti-rotation mechanism (310) provided in the housing (50) for restricting the rotation of the outer ring (76) relative to the housing (50). The anti-rotation mechanism (310) has an elastic member (312), and the elastic member (312) elastically deforms to elastically contact the outer ring (76) in the radial direction of the spindle (21).

Description

Technical Field

[0001] This invention relates to a spindle device of a machine tool.

Background Art

[0002] For example, Japanese Patent Application Laid-Open No. 2020-171986 (Patent Document 1) discloses a spindle device including a spindle, a housing, and a bearing that supports the spindle within the housing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As disclosed in the above Patent Document 1, a spindle device including a housing that houses a spindle that rotates while holding a tool or the like, and a bearing that rotatably supports the spindle within the housing is known. In such a spindle device, when the outer ring of the bearing is fitted to the housing with a clearance fit relationship, the outer ring may rotate with respect to the housing, causing the bearing to exhibit unexpected behavior.

[0005] More specifically, since the ring-shaped outer ring does not have a perfect circular shape due to the influence of machining errors, when the outer ring rotates with respect to the housing, the position of the rotation center of the outer ring fluctuates slightly. As a result, the surface pressure generated between the guide surfaces of the inner and outer rings and the rolling elements that roll between the inner and outer rings changes, causing variations in the thickness of the oil film formed between the guide surfaces and the rolling elements, or the rolling elements not operating smoothly. In such a case, the spindle cannot be rotated stably.

[0006] The objective of this invention is to provide a spindle device for a machine tool that can rotate the spindle stably. [Means for solving the problem]

[0007] The spindle assembly of a machine tool according to this invention comprises a spindle, a housing for the spindle, a bearing having an outer ring and positioned between the spindle and the housing in the radial direction of the spindle, and an anti-rotation mechanism provided in the housing for restricting the rotation of the outer ring relative to the housing. The anti-rotation mechanism has an elastic member, which elastically deforms to elastically contact the outer ring in the radial direction of the spindle. [Effects of the Invention]

[0008] According to this invention, it is possible to provide a spindle device for a machine tool that can rotate the spindle stably. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing a machine tool equipped with a spindle. [Figure 2] This is a perspective view showing the spindle assembly. [Figure 3] This is a cross-sectional view showing the spindle assembly in Figure 2. [Figure 4] This is a cross-sectional view showing the spindle apparatus within the area enclosed by the dashed line IV in Figure 3. [Figure 5] This is a perspective view showing the first bearing group in Figure 4. [Figure 6] This is a front view showing the first bearing group in Figure 4. [Figure 7] This figure partially shows the outer circumferential surface of the outer ring in the first bearing group in Figure 5. [Figure 8] This is a cross-sectional view showing the path of the first wiring from the first bearing group in the spindle assembly shown in Figure 2. [Figure 9] This is a cross-sectional view showing the path of the second wiring from the second bearing group in the spindle assembly shown in Figure 2. [Figure 10]In the spindle device shown in FIG. 2, it is a cross-sectional view showing the paths of the first wiring and the second wiring. [Figure 11] In the spindle device shown in FIG. 2, it is a cross-sectional view showing the anti-rotation mechanism of the outer ring in the first bearing group. [Figure 12] It is a cross-sectional view schematically showing the first step of assembling the first bearing group to the housing and the spindle. [Figure 13] It is a cross-sectional view schematically showing the second step of assembling the first bearing group to the housing and the spindle. [Figure 14] It is a cross-sectional view schematically showing the third step of assembling the first bearing group to the housing and the spindle. [Figure 15] It is another perspective view showing the first bearing group in FIG. 4. [Figure 16] In the spindle device shown in FIG. 2, it is a cross-sectional view showing the oil supply path for the first bearing. [Figure 17] In the spindle device shown in FIG. 2, it is a cross-sectional view showing the oil supply path for the second bearing. [Figure 18] It is a cross-sectional view showing the spindle device in the range surrounded by the two-dot chain line XVIII in FIG. 16. [Figure 19] It is a cross-sectional view showing the spindle device along the line of arrow XIX-XIX in FIG. 18. [Figure 20] It is a cross-sectional view showing the spindle device as viewed in the direction indicated by the arrow XX in FIG. 18. [Figure 21] It is a cross-sectional view showing the oil supply path for the bearing in the comparative example. [Embodiments for Carrying Out the Invention] [[ID=3))

[0010] Embodiments of this invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are given the same numbers.

[0011] [Structure of Machine Tool] Figure 1 is a perspective view showing a machine tool equipped with a spindle. Referring to Figure 1, machine tool 100 is a machining center that processes a workpiece W by bringing a rotating tool T into contact with the workpiece W. Machine tool 100 is a horizontal machining center in which the rotation axis of the tool T extends horizontally. Machine tool 100 is an NC (Numerically Controlled) machine tool in which various operations for workpiece processing are automated by computer numerical control.

[0012] Figure 1 shows the "Z-axis," which is parallel to the horizontal direction and the rotational axis of the tool T; the "X-axis," which is parallel to the horizontal direction and perpendicular to the Z-axis; and the "Y-axis," which is parallel to the vertical direction.

[0013] The machine tool 100 includes a bed 12, a column 14, a spindle unit 10, and a table 16.

[0014] The bed 12 is a base member for supporting the column 14, spindle unit 10, and table 16, etc., and is fixed to the floor surface of a factory or similar facility. The bed 12 is made of a metal such as cast iron.

[0015] Column 14 is supported by the bed 12. Overall, column 14 has a gate-like shape that rises upward from the bed 12. Column 14 is positioned at the end of the bed 12 in the Z-axis direction. Column 14 is movable in the X-axis direction by various feed mechanisms, guide mechanisms, and servo motors.

[0016] The spindle unit 10 is supported by a column 14. The spindle unit 10 as a whole has a cylindrical shape that protrudes from the column 14 in the Z-axis direction. The spindle unit 10 is movable in the Y-axis direction by various feed mechanisms, guide mechanisms, and servo motors.

[0017] The spindle unit 10 has a spindle 21. The spindle 21 has a cylindrical shape centered on a predetermined axis 101 parallel to the Z-axis. The spindle 21 is rotatable around the predetermined axis 101 by a motor. The spindle 21 has a built-in clamping mechanism for holding a tool T for workpiece machining in the machine tool 100. As the spindle 21 rotates, the tool T held on the spindle 21 rotates around the predetermined axis 101.

[0018] The maximum rotational speed of the spindle 21 is, for example, 15,000 (min -1 It may be 30,000 (min) or more. -1 ) or more is also acceptable.

[0019] The predetermined axis 101 corresponds to the rotational axis of the main spindle 21. The radial direction of the main spindle 21 is the radial direction of the cylindrical main spindle 21 and is perpendicular to the predetermined axis 101. The axial direction of the main spindle 21 is the axial direction of the cylindrical main spindle 21 (Z-axis direction) and is the axial direction of the predetermined axis 101. The circumferential direction of the main spindle 21 is the circumferential direction of the cylindrical main spindle 21 and is the circumferential direction centered on the predetermined axis 101.

[0020] Table 16 is supported by bed 12. Table 16 is mounted on bed 12. Table 16 is positioned away from column 14 in the Z-axis direction. Table 16 is a device for holding workpiece W. Table 16 holds workpiece W in a position opposite the spindle 21 in the Z-axis direction. Table 16 is movable in the Z-axis direction by various feed mechanisms, guide mechanisms and servo motors. Table 16 has a built-in swivel mechanism for swiveling a pallet mounted on table 16 around a pivot axis extending in the Y-axis direction (vertical direction).

[0021] In this configuration, the machining position of the workpiece W by the tool T is moved in three dimensions by a combination of the movement of the column 14 in the X-axis direction, the movement of the spindle device 10 (spindle 21) in the Y-axis direction, and the movement of the table 16 in the Z-axis direction.

[0022] Furthermore, the machine tool equipped with the spindle device in the present invention is not limited to the horizontal machining center described above, but may also be a vertical machining center, or a multi-tasking machine having both a turning function using a fixed tool and a milling function using a rotary tool. The machine tool equipped with the spindle device in the present invention may also be an AM / SM hybrid machine capable of additive manufacturing and subtractive manufacturing of a workpiece.

[0023] [Overall structure of the spindle unit] Figure 2 is a perspective view showing the spindle assembly. Figure 3 is a cross-sectional view showing the spindle assembly in Figure 2. In Figures 2 and 3, as well as in subsequent drawings, "spindle front side" corresponds to the side of the spindle assembly 10 where the tool T held by the spindle assembly 10 is positioned, and "spindle rear side" corresponds to the opposite side of the spindle 21 in the axial direction of the spindle assembly 10 from the "spindle front side".

[0024] Referring to Figures 2 and 3, the spindle unit 10 has a clamping mechanism for holding the tool T, which includes a collet 23 capable of gripping the tool T, a drawbar 24 that opens and closes the collet 23 by moving along the axial direction of the spindle 21, and a disc spring 25 fitted on the outer circumference of the drawbar 24. The collet 23, the drawbar 24, and the disc spring 25 are housed in the spindle 21.

[0025] The spindle unit 10 further includes an unclamping cylinder 26 for hydraulically unclamping the clamped tool T. The unclamping cylinder 26 is located at the rear end (rear end) of the spindle unit 10 on the rear side of the spindle.

[0026] In the clamped state, when the tool T is held, the drawbar 24 is pulled towards the rear of the spindle by the spring force of the disc spring 25. This causes the collet 23 to close, and the tool T is gripped by the closed collet 23. When transitioning from the clamped state to the unclamped state, when the tool T is released, the unclamping cylinder 26 is supplied with hydraulic pressure, pushing the drawbar 24 towards the front of the spindle against the spring force of the disc spring 25. This causes the collet 23 to open, and the tool T is released from the open collet 23.

[0027] The spindle unit 10 further comprises a housing 50, a motor housing 33, and a rear housing 45.

[0028] The motor housing 33 is positioned between the housing 50 and the rear housing 45 in the axial direction of the spindle 21. The housing 50 is connected to the front end of the motor housing 33 on the front side of the spindle. The rear housing 45 is connected to the rear end of the motor housing 33 on the rear side of the spindle. The housing 50, motor housing 33, and rear housing 45 extend cylindrically along a predetermined axis 101. As shown in Figure 1, the spindle base 11 is connected to the column 14 so as to be slidable in the Y-axis direction. The motor housing 33 is fitted inside the cylindrical portion of the spindle base 11.

[0029] The spindle unit 10 further comprises a rotor 31 and a stator 32. The rotor 31 has a cylindrical shape centered on a predetermined axis 101. The rotor 31 is fitted onto the outer circumferential surface of the spindle 21. The stator 32 has a cylindrical shape centered on the predetermined axis 101. The stator 32 is fitted onto the inner circumferential surface of the motor housing 33. A small gap is provided between the rotor 31 and the stator 32 in the radial direction of the spindle 21. The rotor 31 and the stator 32, together, constitute a motor for rotating the spindle 21 around the predetermined axis 101.

[0030] The spindle device 10 further includes a first bearing group 71, a second bearing group 72, and a third bearing group 73. The first bearing group 71, the second bearing group 72, and the third bearing group 73 support the spindle 21 so that it can rotate around a predetermined axis 101.

[0031] The first bearing group 71 is positioned between the spindle 21 and the housing 50 in the radial direction of the spindle 21. The first bearing group 71 is positioned between the spindle 21 and the housing body 51, which will be described later, in the radial direction of the spindle 21. In the assembly process of the spindle device 10, the first bearing group 71 is inserted into the housing 50 from the front side of the spindle.

[0032] The second bearing group 72 is positioned between the spindle 21 and the housing 50 in the radial direction of the spindle 21. The second bearing group 72 is positioned between the spindle 21 and the sleeve 61, which will be described later, in the radial direction of the spindle 21. The second bearing group 72 is provided at a distance from the first bearing group 71 in the axial direction of the spindle 21. The second bearing group 72 is positioned further rearward on the spindle than the first bearing group 71. In the assembly process of the spindle device 10, the second bearing group 72 is inserted into the housing 50 from the rear side of the spindle.

[0033] The third bearing group 73 is positioned radially between the spindle 21 and the rear housing 45. The third bearing group 73 is positioned further rearward than the second bearing group 72.

[0034] Figure 4 is a cross-sectional view showing the spindle assembly within the area enclosed by the dashed line IV in Figure 3. Referring to Figures 2 to 4, the housing 50 has a housing body 51 and a sleeve 61. The housing body 51 constitutes the main part of the housing 50. The sleeve 61 is located inside the housing body 51. The sleeve 61, together with a plurality of elastic members 66 (described later), constitutes a preload application mechanism for applying preload to the second bearing group 72.

[0035] The housing body 51 has a cylindrical shape centered on a predetermined axis 101. The housing body 51 includes a front portion 53, an intermediate portion 54, a rear portion 55, and a flange portion 56 as its constituent parts.

[0036] The front section 53, the intermediate section 54, and the rear section 55 are aligned in the axial direction of the spindle 21. The front section 53 is located on the front side of the spindle in the housing body 51. The rear section 55 is located on the rear side of the spindle in the housing body 51. The intermediate section 54 is located between the front section 53 and the rear section 55 in the axial direction of the spindle 21. The inner diameter (diameter of the inner circumferential surface) of the rear section 55 centered on the predetermined shaft 101 is larger than the inner diameter of the front section 53 centered on the predetermined shaft 101.

[0037] The inner diameter of the intermediate portion 54 centered on the predetermined shaft 101 is smaller than the inner diameter of the rear portion 55 centered on the predetermined shaft 101, and also smaller than the inner diameter of the front portion 53 centered on the predetermined shaft 101. The intermediate portion 54 has a convex shape that protrudes radially inward from the main shaft 21 on the inner circumferential surface of the housing 50. The flange portion 56 protrudes radially outward from the rear portion 55 from the main shaft 21 and has a flange shape that circumfers around the main shaft 21 in the circumferential direction.

[0038] The housing 50 (housing body 51) has a first end face 50a and a second end face 50b. The first end face 50a is located at the front end of the housing 50. The first end face 50a is a plane perpendicular to the predetermined axis 101. The first end face 50a faces the front side of the spindle 21 in the axial direction of the spindle 21. The front portion 53 of the housing body 51 has the first end face 50a. The second end face 50b is located on the opposite side of the first end face 50a in the axial direction of the spindle 21. The second end face 50b is located at the rear end of the housing 50. The second end face 50b is a plane perpendicular to the predetermined axis 101. The second end face 50b faces the rear side of the spindle 21 in the axial direction of the spindle 21. The rear portion 55 of the housing body 51 has the second end face 50b.

[0039] The spindle unit 10 further includes a cover 43. The cover 43 is attached to the housing 50 (housing body 51). The cover 43 has a cylindrical shape that forms a frustoconical shape centered on a predetermined axis 101. The cover 43 is positioned to cover the outer circumferential surface 50c of the housing 50 (housing body 51) while facing the end face 56a of the flange portion 56 in the axial direction of the spindle 21. Inside the cover 43, a second internal space 120 is partitioned.

[0040] Figure 5 is a perspective view showing the first bearing group in Figure 4. Figure 6 is a front view showing the first bearing group in Figure 4.

[0041] Referring to Figures 4 to 6, the first bearing group 71 includes a first bearing 71A and a second bearing 71B. Each of the bearings in the first bearing 71A and the second bearing 71B is an angular contact bearing.

[0042] The first bearing 71A has an outer ring 76, an inner ring 77, a plurality of rolling elements 78, and a cage 79. The outer ring 76 is fitted to the inner circumferential surface of the housing 50. The outer ring 76 is fitted to the housing 50 in a clearance fit relationship.

[0043] The inner ring 77 is fitted onto the outer surface of the main shaft 21. The inner ring 77 is fitted to the main shaft 21 in an interlocking fit.

[0044] The rolling elements 78 consist of balls. Multiple rolling elements 78 are arranged between the inner ring 77 and the outer ring 76 in the radial direction of the main shaft 21. A cage 79 holds the multiple rolling elements 78 between the inner ring 77 and the outer ring 76. The multiple rolling elements 78 are held by the cage 79 at intervals from each other in the circumferential direction around a predetermined shaft 101.

[0045] The second bearing 71B has the same shape as the first bearing 71A. The second bearing 71B is aligned with the first bearing 71A in the axial direction of the main shaft 21.

[0046] The first bearing 71A and the second bearing 71B are combined in a parallel configuration. The first bearing 71A and the second bearing 71B are positioned to be able to receive axial loads in the axial direction of the spindle 21, from the rear side of the spindle to the front side of the spindle.

[0047] The first bearing 71A is positioned further forward of the spindle than the second bearing 71B. The second bearing 71B is positioned further rearward of the spindle than the first bearing 71A. The distance between the first end face 50a and the first bearing 71A in the axial direction of the spindle 21 is smaller than the distance between the first end face 50a and the second bearing 71B in the axial direction of the spindle 21. The outer ring 76 of the second bearing 71B is in contact with the intermediate portion 54 of the housing body 51 in the axial direction of the spindle 21.

[0048] The spindle unit 10 further includes a front cover 41 and a nut 42. The front cover 41 has a ring shape centered on a predetermined axis 101. The front cover 41 is attached to the housing 50. The front cover 41 is attached to the housing body 51 (front portion 53). The front cover 41 faces the first end face 50a in the axial direction of the spindle 21. The front cover 41 is in contact with the outer ring 76 of the first bearing 71A in the axial direction of the spindle 21. The outer ring 76 of the first bearing 71A and the outer ring 76 of the second bearing 71B are sandwiched between the front cover 41 and the intermediate portion 54 in the axial direction of the spindle 21.

[0049] The spindle 21 has a threaded portion 28. The threaded portion 28 is provided on the outer circumferential surface of the spindle 21. The threaded portion 28 is provided on the forward side of the spindle 21 in the axial direction of the spindle 21, ahead of the first bearing group 71. The nut 42 is screwed onto the threaded portion 28. The nut 42 is in contact with the inner ring 77 of the first bearing 71A in the axial direction of the spindle 21. The inner rings 77 of the first bearing 71A and the inner rings 77 of the second bearing 71B are sandwiched between the nut 42 and a ring 46, which will be described later, in the axial direction of the spindle 21. The nut 42, together with the front cover 41, forms a labyrinth structure to prevent foreign matter from entering the inside of the housing 50.

[0050] As shown in Figure 4, the second bearing group 72 includes a third bearing 72C and a fourth bearing 72D. Each of the third bearing 72C and the fourth bearing 72D is an angular contact bearing.

[0051] Each of the third bearing 72C and the fourth bearing 72D has an outer ring 76, an inner ring 77, a plurality of rolling elements 78, and a cage 79. Each of the third bearing 72C and the fourth bearing 72D has the same shape as the first bearing 71A.

[0052] The third bearing 72C and the fourth bearing 72D are combined in a parallel configuration. The third bearing 72C and the fourth bearing 72D are positioned to be able to withstand axial loads in the axial direction of the spindle 21, from the front of the spindle to the rear of the spindle.

[0053] The direction of the axial load that the first bearing group 71 (first bearing 71A, second bearing 71B) can withstand and the direction of the axial load that the second bearing group 72 (third bearing 72C, fourth bearing 72D) can withstand are opposite directions along the axial direction of the main shaft 21.

[0054] The third bearing 72C is positioned further forward of the spindle than the fourth bearing 72D. The fourth bearing 72D is positioned further rearward of the spindle than the third bearing 72C. The distance between the second end face 50b and the fourth bearing 72D in the axial direction of the spindle 21 is smaller than the distance between the second end face 50b and the third bearing 72C in the axial direction of the spindle 21.

[0055] Assuming that the first bearing 71A and the second bearing 71B are reversed front to back along the axial direction of the main shaft 21, the third bearing 72C corresponds to the second bearing 71B in that case, and the fourth bearing 72D corresponds to the first bearing 71A in that case.

[0056] The spindle device 10 further includes a ring 46. The ring 46 has a ring shape centered on a predetermined shaft 101. The ring 46 is positioned on the outer circumference of the spindle 21. In the axial direction of the spindle 21, the ring 46 is positioned between the first bearing group 71 and the second bearing group 72. The spindle 21 has an enlarged diameter portion 27. The outer diameter (diameter of the outer circumference) of the enlarged diameter portion 27 centered on the predetermined shaft 101 is larger than the inner diameter (diameter of the inner circumference) of the inner ring 77 centered on the predetermined shaft 101.

[0057] The inner ring 77 of the third bearing 72C is in contact with the intermediate portion 54 of the housing 50 in the axial direction of the main spindle 21. The inner ring 77 of the fourth bearing 72D is in contact with the enlarged diameter portion 27 in the axial direction of the main spindle 21. The inner rings 77 of the third bearing 72C and the fourth bearing 72D are sandwiched between the intermediate portion 54 and the enlarged diameter portion 27 in the axial direction of the main spindle 21.

[0058] The sleeve 61 extends cylindrically around a predetermined shaft 101. The sleeve 61 is positioned inside the housing body 51 so as to be slidable in the axial direction of the main shaft 21. The sleeve 61 is interposed between the housing body 51 and the outer ring 76 of the third bearing 72C and the outer ring 76 of the fourth bearing 72D. The sleeve 61 is prevented from rotating relative to the housing body 51 by an anti-rotation mechanism (not shown).

[0059] The sleeve 61 has a cylindrical portion 62 and a flange portion 63 as its constituent parts. The cylindrical portion 62 has a cylindrical shape centered on a predetermined axis 101. The flange portion 63 protrudes radially inward from the front end of the cylindrical portion 62 toward the main shaft 21 and has a flange shape that circumfers around the predetermined axis 101. In the radial direction of the main shaft 21, the cylindrical portion 62 is interposed between the housing body 51 (rear portion 55) and the outer ring 76 of the third bearing 72C and the outer ring 76 of the fourth bearing 72D. In the axial direction of the main shaft 21, the flange portion 63 is interposed between the housing body 51 (intermediate portion 54) and the outer ring 76 of the third bearing 72C.

[0060] The spindle device 10 further comprises a plurality of elastic members 66. Each elastic member 66 consists of a coil spring extending spirally along the axial direction of the spindle 21. The plurality of elastic members 66 are attached to the housing body 51. The plurality of elastic members 66 are spaced apart from each other in the circumferential direction of the spindle 21. The plurality of elastic members 66 are in contact with the sleeve 61 in the axial direction of the spindle 21. The plurality of elastic members 66 impart an elastic force to the sleeve 61 in the axial direction of the spindle 21, from the front side of the spindle to the rear side of the spindle.

[0061] As the spindle 21 expands due to its rotation, it stretches from the front to the rear. In this case, if the inner ring 77 of the second bearing group 72 slides with the spindle 21 from the front to the rear, the multiple rolling elements 78 will not be fixed between the inner ring 77 and the outer ring 76. In contrast, the sleeve 61 receives elastic force from the multiple elastic members 66 and slides from the front to the rear of the spindle. By pushing the outer ring 76 from the front to the rear of the spindle, the sleeve 61 can hold the multiple rolling elements 78 at a constant pressure between the inner ring 77 and the outer ring 76.

[0062] Furthermore, instead of the elastic force provided by the multiple elastic members 66 described above, hydraulic pressure may be used in the preload application mechanism for applying preload to the second bearing group 72.

[0063] [Detailed structure of the spindle unit] (Embodiment 1) In this embodiment, the wiring routes in the spindle device 10 will be described in detail. Figure 7 is a diagram that partially shows the outer circumferential surface of the outer ring in the first bearing group in Figure 5. In Figure 7, the outer circumferential surface 76a of the outer ring 76 in the first bearing group 71 is shown in a planar unfolded view.

[0064] Referring to Figures 4 to 7, the spindle unit 10 further has first wiring 210 (210A, 210B). The first wiring 210 is for sensing the state of the first bearing group 71.

[0065] More specifically, the first wiring 210 is an optical fiber for sensing the strain of the outer ring 76 in the first bearing group 71. The optical fiber is wound around the outer circumferential surface 76a of the outer ring 76. Optical grooves are provided at equal pitches on the inner circumferential surface of the optical fiber. When the outer ring 76 expands due to heat or is subjected to a load, the pitch of the optical grooves changes. At this time, the frequency and intensity of the reflected light from the grooves within the optical fiber change, and the strain of the outer ring 76 is sensed by detecting this change.

[0066] As shown in Figures 5 to 7, the outer rings 76 of the first bearing 71A and the second bearing 71B are provided with a first wiring groove 81, a second wiring groove 82, and a third wiring groove 83.

[0067] The first wiring groove 81 is recessed from the outer circumferential surface 76a of the outer ring 76 and has a groove shape that circumfers around the predetermined shaft 101. The first wiring groove 81 is located in the axial direction of the predetermined shaft 101, closer to the end face of the outer ring 76 on the rear side of the main spindle than to the end face of the outer ring 76 on the front side of the main spindle. The groove depth of the first wiring groove 81 is greater than the groove depths of the second wiring groove 82 and the third wiring groove 83.

[0068] The second wiring groove 82 is recessed from the outer circumferential surface 76a of the outer ring 76 and has a groove shape that extends in the axial direction of the predetermined shaft 101. The second wiring groove 82 extends between the end face of the outer ring 76 on the front side of the main spindle and the end face of the outer ring 76 on the rear side of the main spindle in the axial direction of the predetermined shaft 101. The second wiring groove 82 penetrates the outer ring 76 in the axial direction of the predetermined shaft 101. The second wiring groove 82 is provided at a single angular position in the circumferential direction centered on the predetermined shaft 101. The second wiring groove 82 intersects the first wiring groove 81 at a right angle. The second wiring groove 82 straddles the space between the first bearing 71A and the second bearing 71B and extends in the axial direction of the predetermined shaft 101. The second wiring groove 82 extends in a straight line between the first bearing 71A and the second bearing 71B.

[0069] The third wiring groove 83 is recessed from the outer circumferential surface 76a of the outer ring 76 and has a groove shape that extends between the first wiring groove 81 and the second wiring groove 82. The third wiring groove 83 is connected to the first wiring groove 81 at a position circumferentially separated from the second wiring groove 82 around the predetermined shaft 101. The third wiring groove 83 is connected to the second wiring groove 82 at a position adjacent to the end face of the outer ring 76 on the front side of the main shaft in the axial direction of the predetermined shaft 101. The third wiring groove 83 extends in an arc shape between the first wiring groove 81 and the second wiring groove 82.

[0070] As shown in Figure 7, the first wiring 210A is an optical fiber for sensing the strain of the outer ring 76 of the first bearing 71A. The first wiring 210B is an optical fiber for sensing the strain of the outer ring 76 of the second bearing 71B.

[0071] The first wiring 210A is routed on the outer circumferential surface 76a of the outer ring 76 of the first bearing 71A. The first wiring 210A passes through the second wiring groove 82, the first wiring groove 81, and the third wiring groove 83 of the first bearing 71A in that order. The first wiring 210B passes through the outer circumferential surface 76a of the outer ring 76 of the first bearing 71A and is routed on the outer circumferential surface 76a of the outer ring 76 of the second bearing 71B. The first wiring 210B passes through the second wiring groove 82 of the first bearing 71A and enters the outer circumferential surface 76a of the outer ring 76 of the second bearing 71B. The first wiring 210B passes through the second wiring groove 82, the first wiring groove 81, and the third wiring groove 83 of the second bearing 71B in that order. The first wiring 210B passes through the second wiring groove 82 in the first bearing 71A again and exits from the outer circumferential surface 76a of the outer ring 76 of the second bearing 71B.

[0072] With the above configuration, the first wiring 210 (210A, 210B) is drawn out from the first bearing group 71 to the front side of the spindle 21 in the axial direction through the second wiring groove 82.

[0073] Figure 8 is a cross-sectional view showing the path of the first wiring from the first bearing group in the spindle device shown in Figure 2. Referring to Figures 7 and 8, the first wiring 210 (210A, 210B) extends from the first bearing group 71 to a position facing the first end face 50a in the axial direction of the spindle 21. The first wiring 210 extends from a position where the outer ring 76 of the first bearing group 71 is projected radially onto the spindle 21 to a position facing the first end face 50a in the axial direction of the spindle 21.

[0074] A first internal space 110 is partitioned inside the front cover 41. The front cover 41, together with the housing 50 (housing body 51), forms the first internal space 110. The first internal space 110 is formed in the axial direction of the main spindle 21, at a position opposite the first end face 50a. When viewed in the axial direction of the main spindle 21, the first internal space 110 has a width in the radial direction of the main spindle 21 and extends in an arc shape along the circumferential direction of the main spindle 21. The angular range in which the first internal space 110 extends in an arc shape along the circumferential direction of the main spindle 21 includes the angular position in which the second wiring groove 82 is provided in the outer ring 76 of the first bearing group 71 and the angular position in the housing 50 where the first wiring hole 241, described later, opens to the first end face 50a.

[0075] The first wiring 210, which extends from the first bearing group 71 to a position facing the first end face 50a in the axial direction of the main shaft 21, enters the first internal space 110 on the first end face 50a. Within the first internal space 110, the first wiring 210 extends in the circumferential direction of the main shaft 21.

[0076] Figure 9 is a cross-sectional view showing the path of the second wiring from the second bearing group in the spindle device shown in Figure 2. Referring to Figure 9, the spindle device 10 further has a second wiring 220. The second wiring 220 is for sensing the state of the second bearing group 72. More specifically, the second wiring 220 is an optical fiber for sensing the strain of the outer ring 76 in the second bearing group 72 (third bearing 72C, fourth bearing 72D).

[0077] Each outer ring 76 of the third bearing 72C and the fourth bearing 72D is provided with a first wiring groove 81, a second wiring groove 82, and a third wiring groove 83, in the same manner as those provided with the outer rings 76 of the first bearing 71A and the second bearing 71B.

[0078] As already explained, assuming that the first bearing 71A and the second bearing 71B are reversed front to back along the axial direction of the main shaft 21, the third bearing 72C corresponds to the second bearing 71B in that case, and the fourth bearing 72D corresponds to the first bearing 71A in that case. Furthermore, the second wiring groove 82 provided on the outer ring 76 of the first bearing group 71 and the second wiring groove 82 provided on the outer ring 76 of the second bearing group 72 are positioned at offset angular positions relative to each other in the circumferential direction of the main shaft 21.

[0079] In this configuration, the second wiring 220 is drawn out from the second bearing group 72 to the rear side of the spindle 21 in the axial direction through the second wiring groove 82.

[0080] The second wiring 220 extends from the second bearing group 72 to a position facing the second end face 50b in the axial direction of the spindle 21. The second wiring 220 extends from a position where the outer ring 76 of the second bearing group 72 is projected radially onto the spindle 21 to a position facing the second end face 50b in the axial direction of the spindle 21. At the position facing the second end face 50b in the axial direction of the spindle 21, the second wiring 220 extends in the circumferential direction of the spindle 21.

[0081] Figure 10 is a cross-sectional view showing the paths of the first and second wiring in the spindle apparatus in Figure 2. Referring to Figure 10, the first wiring 210 and the second wiring 220 merge between the first end face 50a and the second end face 50b in the axial direction of the spindle 21.

[0082] The housing 50 (housing body 51) is provided with a first wiring hole 241 and a second wiring hole 242. The first wiring hole 241 and the second wiring hole 242 are located at the same angular position relative to each other in the circumferential direction of the main shaft 21. The first wiring hole 241 and the second wiring hole 242 are located at an angular position offset from the second wiring groove 82 provided in the outer ring 76 of the first bearing group 71 in the circumferential direction of the main shaft 21. The first wiring hole 241 and the second wiring hole 242 are located at an angular position offset from the second wiring groove 82 provided in the outer ring 76 of the second bearing group 72 in the circumferential direction of the main shaft 21.

[0083] The first wiring hole 241 opens at the first end face 50a. The first wiring hole 241 communicates with the first internal space 110 at the first end face 50a. The first wiring hole 241 extends from the first end face 50a toward the second end face 50b in the axial direction of the spindle 21. The first wiring hole 241 extends from the first end face 50a toward the spindle 21 in the radial direction of the spindle 21. The first wiring hole 241 extending from the first end face 50a opens between the first end face 50a and the second end face 50b in the axial direction of the spindle 21. The first wiring hole 241 extending from the first end face 50a opens at the outer circumferential surface 50c of the housing 50 (housing body 51). The first wiring hole 241 communicates with the second internal space 120 on the outer circumferential surface 50c of the housing 50.

[0084] The second wiring hole 242 opens at the second end face 50b. The second wiring hole 242 extends from the second end face 50b toward the first end face 50a in the axial direction of the spindle 21. The second wiring hole 242 extends from the second end face 50b toward the spindle 21 in the radial direction of the spindle 21. The second wiring hole 242 extending from the second end face 50b opens between the first end face 50a and the second end face 50b in the axial direction of the spindle 21. The second wiring hole 242 extending from the second end face 50b opens at the end face 56a of the flange portion 56. The second wiring hole 242 communicates with the second internal space 120 at the end face 56a of the flange portion 56.

[0085] The total length of the second wiring hole 242 is less than the total length of the first wiring hole 241. The total length of the second wiring hole 242 may be greater than or equal to the total length of the first wiring hole 241.

[0086] The first wiring 210 enters the second internal space 120 through the first wiring hole 241. The second wiring 220 enters the second internal space 120 through the second wiring hole 242. The first wiring 210 and the second wiring 220 merge in the second internal space 120. The first wiring 210 and the second wiring 220 merge in the axial direction of the spindle 21 at a position closer to the second end face 50b than to the first end face 50a. The first wiring 210 and the second wiring 220 may also merge in the axial direction of the spindle 21 at a position closer to the first end face 50a than to the second end face 50b.

[0087] The housing 50 (housing body 51) is further provided with a third wiring hole 243. The third wiring hole 243 is located at the same angular position as the first wiring hole 241 and the second wiring hole 242 in the circumferential direction of the main shaft 21.

[0088] The third wiring hole 243 opens at the end face 56a of the flange portion 56. The third wiring hole 243 communicates with the second internal space 120 at the end face 56a of the flange portion 56. The third wiring hole 243 extends in the axial direction of the main shaft 21 and passes through the flange portion 56. The third wiring hole 243 is connected to the wiring hole provided in the main shaft base 11 in Figure 1.

[0089] The first wiring 210 and the second wiring 220 from the second internal space 120 are routed through the third wiring hole 243 to the rear side of the spindle.

[0090] To summarize the configuration of the spindle device 10 in Embodiment 1 of the present invention as described above, the spindle device 10 of the machine tool in this embodiment has a spindle 21, a first end face 50a, a second end face 50b located on the opposite side of the first end face 50a in the axial direction of the spindle 21, a housing 50 that houses the spindle 21, a first bearing group 71 located between the spindle 21 and the housing 50 in the radial direction of the spindle 21, and located between the spindle 21 and the housing 50 in the radial direction of the spindle 21, with a gap between the first bearing group 71 and the second end face 50b in the axial direction of the spindle 21. The system includes a second bearing group 72 provided in between, a first wiring 210 extending from the first bearing group 71 or the first bearing group 71 as a housing 50 to a position facing the first end face 50a in the axial direction of the spindle 21 for sensing the state of the first bearing group 71, and a second wiring 220 extending from the second bearing group 72 or the second bearing group 72 as a housing 50 to a position facing the second end face 50b in the axial direction of the spindle 21, merging with the first wiring 210 between the first end face 50a and the second end face 50b in the axial direction of the spindle 21 for sensing the state of the second bearing group 72.

[0091] With this configuration, the first wiring 210 extends from the first bearing group 71 to a position facing the first end face 50a in the axial direction of the spindle 21. Therefore, when assembling the spindle device 10, the worker can route the first wiring 210 from a position facing the first end face 50a in the axial direction of the spindle 21. In this case, the first wiring 210 can be routed to a position facing the first end face 50a without crossing the second bearing group 72 in the axial direction of the spindle 21, thus shortening the wiring length of the first wiring 210.

[0092] Furthermore, since the second wiring 220 extends from the second bearing group 72 to a position facing the second end face 50b in the axial direction of the spindle 21, when assembling the spindle device 10, the worker can route the second wiring 220 from a position facing the second end face 50b in the axial direction of the spindle 21. In this case, since the second wiring 220 can be routed to a position facing the second end face 50b in the axial direction of the spindle 21 without crossing the first bearing group 71, the wiring length of the second wiring 220 can be shortened. Moreover, since the second wiring 220 merges with the first wiring 210 between the first end face 50a and the second end face 50b in the axial direction of the spindle 21, the merged first wiring 210 and second wiring 220 can be routed together.

[0093] For the reasons stated above, the routing of the first wiring 210 and the second wiring 220 is made easier, resulting in good workability during the assembly of the spindle unit 10.

[0094] Furthermore, the housing 50 includes a housing body 51 and a sleeve 61 positioned inside the housing body 51 so as to be slidable in the axial direction of the spindle 21, for applying preload to the second bearing group 72. The second bearing group 72 is positioned between the spindle 21 and the sleeve 61 in the radial direction of the spindle 21. The sleeve 61 is positioned between the first bearing group 71 and the second bearing group 72 in the axial direction of the spindle 21 and has a flange portion 63 that abuts against the second bearing group 72 in the axial direction of the spindle 21.

[0095] With this configuration, the second wiring 220 extends from the second bearing group 72 to a position facing the second end face 50b in the axial direction of the main shaft 21. Therefore, the second wiring 220 can be extended to a position facing the second end face 50b without crossing the boundary between the housing body 51 and the flange portion 63. This prevents the second wiring 220 from breaking due to the sliding operation of the sleeve 61.

[0096] Furthermore, the housing 50 is provided with a first wiring hole 241 extending from the first end face 50a, opening between the first end face 50a and the second end face 50b in the axial direction of the spindle 21, and in which the first wiring 210 is located, and a second wiring hole 242 extending from the second end face 50b, opening between the first end face 50a and the second end face 50b in the axial direction of the spindle 21, and in which the second wiring 220 is located.

[0097] With this configuration, the first wiring 210 from a position facing the first end face 50a is placed in the first wiring hole 241, and the second wiring 220 from a position facing the second end face 50b is placed in the second wiring hole 242, thereby allowing the first wiring 210 and the second wiring 220 to merge between the first end face 50a and the second end face 50b in the axial direction of the main spindle 21.

[0098] In this embodiment, the first and second wirings in the present invention are described as optical fibers for sensing the strain of the outer ring of the bearing, but the invention is not limited to this. For example, the first and second wirings in the present invention may be wirings extending from a temperature sensor for detecting the temperature of the bearing, or wirings extending from a distance measuring sensor for detecting the size of the gap between the bearing and the housing. When these sensors are attached to the housing, the first and second wirings in the present invention may be configured to extend from the housing. The second wiring in the present invention may be configured to extend from the housing body, or it may be configured to extend from the sleeve.

[0099] In this invention, the first and second wirings are conductors that transmit signals, information, or electricity (power supply / electrical signals), or optical fibers that transmit light.

[0100] Furthermore, each bearing group in the first bearing group and the second bearing group in the present invention may consist of a single bearing or of three or more bearings.

[0101] (Embodiment 2) In this embodiment, the anti-rotation mechanism for the outer ring 76 in the first bearing group 71 will be described in detail. Figure 11 is a cross-sectional view showing the anti-rotation mechanism for the outer ring in the first bearing group in the spindle device shown in Figure 2.

[0102] Referring to Figures 5, 6, and 11, the outer rings 76 of the first bearing 71A and the second bearing 71B are further provided with anti-rotation grooves 86.

[0103] The anti-rotation groove 86 is recessed from the outer circumferential surface 76a of the outer ring 76 and has a groove shape that extends in the axial direction of the predetermined shaft 101. The anti-rotation groove 86 extends between the end face of the outer ring 76 on the front side of the main spindle and the end face of the outer ring 76 on the rear side of the main spindle in the axial direction of the predetermined shaft 101. The anti-rotation groove 86 penetrates the outer ring 76 in the axial direction of the predetermined shaft 101. The anti-rotation groove 86 is provided at a single angular position in the circumferential direction centered on the predetermined shaft 101. The anti-rotation groove 86 straddles the first bearing 71A and the second bearing 71B and extends in the axial direction of the predetermined shaft 101. The anti-rotation groove 86 extends in a straight line between the first bearing 71A and the second bearing 71B.

[0104] The anti-rotation groove 86 is provided at an angular position offset from the second wiring groove 82 in the circumferential direction centered on the predetermined axis 101.

[0105] As shown in Figure 11, the spindle unit 10 further includes an anti-rotation mechanism 310 (310A, 310B). The anti-rotation mechanism 310 is provided in the housing 50 (housing body 51).

[0106] The anti-rotation mechanism 310 is configured to restrict the rotation of the outer ring 76 of the first bearing group 71 relative to the housing 50 (housing body 51). The anti-rotation mechanism 310A is configured to restrict the rotation of the outer ring 76 of the first bearing 71A relative to the housing 50. The anti-rotation mechanism 310B is configured to restrict the rotation of the outer ring 76 of the second bearing 71B relative to the housing 50. The structures of the anti-rotation mechanisms 310A and 310B are identical to each other.

[0107] The anti-rotation mechanism 310 has an elastic member 312. The elastic member 312 is provided in the housing 50. The elastic member 312 is made of rubber material. The elastic member 312 is an annular elastic body. The anti-rotation mechanism 310 elastically contacts the outer ring 76 in the radial direction of the main shaft 21 due to the elastic deformation of the elastic member 312.

[0108] The housing 50 (housing body 51) is provided with a first anti-rotation hole 321 and a second anti-rotation hole 322. The first anti-rotation hole 321 and the second anti-rotation hole 322 are provided in the front portion 53. The first anti-rotation hole 321 has a bottomed hole shape that is recessed radially inward from the outer circumferential surface 50c of the housing 50 toward the main shaft 21. A threaded portion 326 is provided on the inner circumferential surface of the housing 50 that defines the first anti-rotation hole 321.

[0109] The second anti-rotation hole 322 extends radially inward from the bottom of the first anti-rotation hole 321 and opens to the inner circumferential surface of the housing 50. The diameter of the second anti-rotation hole 322 is smaller than the diameter of the first anti-rotation hole 321. The second anti-rotation hole 322 opens radially in the direction of the main spindle 21, opposite the anti-rotation groove 86.

[0110] The anti-rotation mechanism 310 further includes a pin 311. The pin 311 is mounted relative to the housing 50 so as to be slidable in the radial direction of the spindle 21.

[0111] The pin 311 has a shaft portion 316 and a head portion 317 as its constituent parts. The shaft portion 316 has a cylindrical shape. The shaft portion 316 is positioned in the second anti-rotation hole 322. The diameter of the shaft portion 316 is smaller than the diameter of the second anti-rotation hole 322. The shaft portion 316 is fitted into the second anti-rotation hole 322 due to a clearance fit. The shaft portion 316 is guided radially along the main shaft 21 by the inner circumferential surface of the housing 50 that defines the second anti-rotation hole 322. The head portion 317 is provided at the end of the shaft portion 316. The head portion 317 is positioned in the first anti-rotation hole 321. The diameter of the head portion 317 is larger than the diameter of the shaft portion 316 and smaller than the diameter of the first anti-rotation hole 321.

[0112] The pin 311 (shaft portion 316) is in contact with the housing 50 in the radial direction of the main shaft 21. The pin 311 is in contact with the bottom of the anti-rotation groove 86.

[0113] The anti-rotation mechanism 310 further includes a bolt 313. The bolt 313 is screwed into the threaded portion 326. The elastic member 312 is positioned in the first anti-rotation hole 321. The elastic member 312 is positioned between the bolt 313 and the pin 311 (head 317). The elastic member 312 is positioned such that its central axis, which is an annular sealing member, is parallel to the radial direction of the main shaft 21. The elastic member 312 is in contact with the pin 311 (head 317) from the radially outer side of the main shaft 21. The elastic member 312 is positioned between the bolt 313 and the pin 311 in a state of compression deformation in the radial direction of the main shaft 21. The elastic member 312 applies an elastic force to the pin 311 toward the radially inward side of the main shaft 21.

[0114] In this configuration, the pin 311 receives an elastic force from the elastic member 312 and elastically contacts the outer ring 76 in the radial direction of the main shaft 21.

[0115] The spindle unit 10 further includes a cover 327. The cover 327 is attached to the housing 50 (housing body 51). The cover 327 is attached to the outer circumferential surface 50c of the housing 50 so as to cover the bolts 313.

[0116] Figures 12 to 14 are schematic cross-sectional views illustrating the process of assembling the first bearing group to the housing and main shaft.

[0117] Referring to Figures 5, 6, and 12 to 14, each outer ring 76 of the first bearing 71A and the second bearing 71B is further provided with a connecting groove 88.

[0118] The connecting groove 88 is recessed from the outer circumferential surface 76a of the outer ring 76 and has a groove shape that extends in the axial direction of the predetermined shaft 101. The connecting groove 88 extends in the axial direction of the predetermined shaft 101 between the end face of the outer ring 76 on the front side of the main spindle and the end face of the outer ring 76 on the rear side of the main spindle. The connecting groove 88 penetrates the outer ring 76 in the axial direction of the predetermined shaft 101. The connecting groove 88 straddles the first bearing 71A and the second bearing 71B and extends in the axial direction of the predetermined shaft 101. The connecting groove 88 extends in a straight line between the first bearing 71A and the second bearing 71B.

[0119] The connecting groove 88 is provided at a single angular position in the circumferential direction centered on the predetermined axis 101. The connecting groove 88 is provided at an angular position offset from the second wiring groove 82 in the circumferential direction centered on the predetermined axis 101. The connecting groove 88 is provided at an angular position offset from the anti-rotation groove 86 in the circumferential direction centered on the predetermined axis 101.

[0120] As shown in Figure 14, the spindle assembly 10 further has a connecting pin 331. The connecting pin 331 is located in a connecting groove 88. The connecting pin 331 straddles the first bearing 71A and the second bearing 71B and extends axially along the spindle 21. The connecting pin 331 connects the outer ring 76 of the first bearing 71A and the outer ring 76 of the second bearing 71B.

[0121] When assembling the spindle unit 10, the first bearing 71A and the second bearing 71B are aligned in the axial direction of the predetermined shaft 101, as shown in Figure 12. A connecting pin 331 is placed in the connecting groove 88, and, as shown in Figure 7, the first wiring 210 from the first bearing 71A and the second bearing 71B is pulled out through the second wiring groove 82 from the outer peripheral surface 76a of the outer ring 76 in the axial direction of the predetermined shaft 101.

[0122] Next, as shown in Figure 13, the first bearing group 71 is inserted into the housing 50 (housing body 51). At this time, the connecting pin 331 restricts the outer ring 76 of the first bearing 71A and the outer ring 76 of the second bearing 71B from rotating relative to each other around the predetermined axis 101. This prevents the first wiring 210, which is arranged in the second wiring groove 82, from breaking. As shown in Figure 11, the pin 311 is fitted into the anti-rotation groove 86 by rotating the outer ring 76 in the circumferential direction around the predetermined axis 101.

[0123] Next, as shown in Figure 14, the housing 50 to which the first bearing group 71 is assembled is heated, causing the inner ring 77 to expand radially outward around the circumference centered on the predetermined shaft 101. Then, the main shaft 21 is inserted inside the inner ring 77. With these steps, the assembly of the first bearing group 71 to the housing 50 and the main shaft 21 is completed.

[0124] To summarize the configuration of the spindle device 10 in Embodiment 2 of the present invention described above, the spindle device 10 in this embodiment comprises a spindle 21, a housing 50 that houses the spindle 21, a first bearing group 71 (first bearing 71A, second bearing 71B) having an outer ring 76 and positioned between the spindle 21 and the housing 50 in the radial direction of the spindle 21, and an anti-rotation mechanism 310 (310A, 310B) provided on the housing 50 to restrict the rotation of the outer ring 76 relative to the housing 50. The anti-rotation mechanism 310 has an elastic member 312, and the elastic member 312 elastically deforms to elastically contact the outer ring 76 in the radial direction of the spindle 21.

[0125] With this configuration, the rotation of the outer ring 76 relative to the housing 50 is restricted by the anti-rotation mechanism 310, thereby preventing the first bearing group 71 from exhibiting unexpected behavior. In this case, since the anti-rotation mechanism 310 elastically contacts the outer ring 76 in the radial direction of the main shaft 21, even if the outer ring 76 undergoes thermal expansion radially outward from the main shaft 21, it is possible to prevent excessive external force from being applied to the outer ring 76 from the anti-rotation mechanism 310. This minimizes the influence of fluctuations in the external force applied to the first bearing group 71 from the anti-rotation mechanism 310, allowing for the stable formation of an oil film between, for example, the rolling elements 78 and the guide surfaces of the outer ring 76 and inner ring 77. As a result, the main shaft 21 can be rotated stably by the first bearing group 71.

[0126] Furthermore, the anti-rotation mechanism 310 is mounted to the housing 50 so as to be slidable in the radial direction of the spindle 21, and further has a pin 311 that contacts the outer ring 76 in the radial direction of the spindle 21. The elastic member 312 is provided to impart an elastic force to the pin 311 toward the radially inward direction of the spindle 21 by elastically deforming.

[0127] With this configuration, even if the outer ring 76 undergoes thermal expansion radially outward from the main shaft 21, the pin 311 slides radially outward from the main shaft 21 while resisting the elastic force from the elastic member 312. This prevents excessive external force from being applied from the pin 311 to the outer ring 76.

[0128] Furthermore, the anti-rotation mechanism 310 is provided at a single angular position in the circumferential direction of the main shaft 21. With this configuration, the anti-rotation mechanism 310 can be easily constructed, while the main shaft 21 can be rotated stably by the first bearing group 71.

[0129] Furthermore, the outer ring 76 is provided with an anti-rotation groove 86 that is recessed from the outer circumferential surface 76a of the outer ring 76. The anti-rotation mechanism 310 abuts against the bottom of the anti-rotation groove 86.

[0130] With this configuration, if the outer ring 76 attempts to rotate relative to the housing 50, the anti-rotation mechanism 310 needs to disengage from the anti-rotation groove 86, thus more reliably restricting the rotation of the outer ring 76.

[0131] Furthermore, the spindle device 10 includes a first bearing 71A and a second bearing 71B aligned with the first bearing 71A in the axial direction of the spindle 21. The outer rings 76 of the first bearing 71A and the second bearing 71B are provided with a second wiring groove 82, which is recessed from the outer circumferential surface 76a of the outer ring 76, spans between the first bearing 71A and the second bearing 71B, and extends in the axial direction of the spindle 21. The spindle device 10 further includes a first wiring 210, which is wiring arranged in the second wiring groove 82.

[0132] With this configuration, by restricting the rotation of the outer rings 76 of the first bearing 71A and the second bearing 71B relative to the housing 50, it is possible to prevent the first wiring 210, which is located in the second wiring groove 82, from breaking.

[0133] In this embodiment, the present invention has described a case where the elastic member is an annular sealing member, but it is not limited to this. The elastic member in this invention may be a spring member such as a disc spring or a coil spring.

[0134] Furthermore, the anti-rotation mechanism in the present invention may be composed of an elastic member having a pin shape. In this case, the tip of the pin-shaped elastic member elastically contacts the outer ring in the radial direction of the main shaft.

[0135] (Embodiment 3) In this embodiment, the supply path of oil (lubricating oil) to the first bearing group 71 will be mainly described. Figure 15 is another perspective view showing the first bearing group in Figure 4.

[0136] Referring to Figures 6 and 15, the outer rings 76 of the first bearing 71A and the second bearing 71B are further provided with second oil holes 92 (92A, 92B).

[0137] The second oil hole 92 opens on the outer circumferential surface 76a of the outer ring 76. The second oil hole 92 has a circular opening shape on the outer circumferential surface 76a of the outer ring 76. The second oil hole 92 extends between the outer circumferential surface 76a and the inner circumferential surface of the outer ring 76. The second oil hole 92 is a through hole that penetrates the outer ring 76 in the radial direction of the circumference centered on a predetermined axis 101.

[0138] The second oil hole 92 is located at an angular position offset from the second wiring groove 82 in the circumferential direction centered on the predetermined axis 101. The second oil hole 92 is located at an angular position offset from the anti-rotation groove 86 in the circumferential direction centered on the predetermined axis 101. The second oil hole 92 is located at an angular position offset from the connecting groove 88 in the circumferential direction centered on the predetermined axis 101. The second oil holes 92A and 92B are located at angular positions offset from each other in the circumferential direction centered on the predetermined axis 101.

[0139] Figure 16 is a cross-sectional view showing the oil supply path to the first bearing in the spindle assembly shown in Figure 2. Figure 17 is a cross-sectional view showing the oil supply path to the second bearing in the spindle assembly shown in Figure 2.

[0140] Referring to Figures 16 and 17, the housing 50 (housing body 51) is further provided with sealing grooves 93 (93A, 93B), first oil holes 91 (91A, 91B), and oil supply holes 90 (90A, 90B).

[0141] The spindle unit 10 further includes a mixing valve 410. Oil and air are supplied to the mixing valve 410. The mixing valve 410 adjusts the amount of at least one of the oil and air to discharge oil-air, which is a mixture of oil and air. The mixing valve 410 is connected to an oil supply port 90 via piping such as a copper pipe. Oil-air from the mixing valve 410 is supplied to the oil supply port 90.

[0142] The oil supply hole 90A, the first oil hole 91A, and the sealing groove 93A, and the oil supply hole 90B, the first oil hole 91B, and the sealing groove 93B are provided at offset angular positions relative to each other in the circumferential direction of the main shaft 21. As shown in Figure 16, the oil air from the mixing valve 410 is supplied to the first bearing 71A by passing through the oil supply hole 90A, the first oil hole 91A, and the sealing groove 93A in that order. As shown in Figure 17, the oil air from the mixing valve 410 is supplied to the second bearing 71B by passing through the oil supply hole 90B, the first oil hole 91B, and the sealing groove 93B in that order.

[0143] Furthermore, the second oil hole 92B provided in the first bearing 71A and the second oil hole 92A provided in the second bearing 71B are not used as oil passages.

[0144] Figure 18 is a cross-sectional view of the spindle assembly within the area enclosed by the dashed-dot line XVIII in Figure 16. Figure 19 is a cross-sectional view of the spindle assembly along the line XIX-XIX in Figure 18. Figure 20 is a cross-sectional view of the spindle assembly as seen in the direction indicated by arrow XX in Figure 18. In Figure 20, for illustrative purposes, the opening of the second oil hole 92 (92A) is shown by a dashed-dot line.

[0145] The configuration of the oil supply path to the first bearing 71A and the configuration of the oil supply path to the second bearing 71B are identical. In the following, a more specific configuration of the oil supply path will be described, with reference to the oil supply path to the first bearing 71A shown in Figures 16 and 18 to 20 as representative examples.

[0146] Referring to Figures 16 and 18 to 20, the sealing groove 93 is recessed from the inner circumferential surface 50d of the housing 50 and has a circular opening shape when viewed radially from the spindle 21. The sealing groove 93 opens on the inner circumferential surface 50d of the housing 50. The groove bottom 93a of the sealing groove 93 is defined at a position shifted radially outward from the opening of the sealing groove 93 on the inner circumferential surface 50d of the housing 50, relative to the spindle 21. The groove bottom 93a of the sealing groove 93 consists of a plane perpendicular to the radial direction of the spindle 21. The groove depth of the sealing groove 93 is smaller than the thickness of the sealing member 96, which will be described later.

[0147] The opening of the sealing groove 93 on the inner circumferential surface 50d of the housing 50 and the opening of the second oil hole 92 on the outer circumferential surface 76a of the outer ring 76 are opposite each other in the radial direction of the main spindle 21. The opening centers of the sealing groove 93 on the inner circumferential surface 50d of the housing 50 and the opening centers of the second oil hole 92 on the outer circumferential surface 76a of the outer ring 76 coincide with each other.

[0148] The first oil hole 91 opens into the bottom 93a of the sealing groove 93. The first oil hole 91 has a circular opening shape at the bottom 93a of the sealing groove 93. The diameter of the opening of the first oil hole 91 at the bottom 93a of the sealing groove 93 is smaller than the diameter of the bottom 93a of the sealing groove 93. The center of the opening of the first oil hole 91 at the bottom 93a of the sealing groove 93 and the center of the bottom 93a of the sealing groove 93 coincide with each other.

[0149] The first oil hole 91 extends radially to the spindle 21. The first oil hole 91 may also extend obliquely to the radial direction of the spindle 21. The first oil hole 91 and the sealing groove 93 are located at a single angular position in the circumferential direction of the spindle 21.

[0150] As shown in Figure 16, the oil supply hole 90 extends across the flange portion 56, rear portion 55, intermediate portion 54, and front portion 53 of the housing body 51. The oil supply hole 90 communicates with the first oil hole 91. The oil supply hole 90 communicates with the end of the first oil hole 91 on the radially outer side of the main shaft 21. Oil air from the mixing valve 410 flows into the first oil hole 91 through the oil supply hole 90.

[0151] The spindle device 10 further includes an annular sealing member 96. The sealing member 96 is positioned in a sealing groove 93. The sealing member 96 is positioned such that its central axis extends along the radial direction of the spindle 21 (the depth direction of the sealing groove 93). The inner diameter of the sealing member 96 is larger than the diameter of the opening of the first oil hole 91 at the bottom 93a of the sealing groove 93. The sealing member 96 is compressed between the bottom 93a of the sealing groove 93 and the outer circumferential surface 76a of the outer ring 76.

[0152] The sealing member 96 seals the oil (oil-air) passage between the first oil hole 91 and the second oil hole 92. Oil-air (oil) from the first oil hole 91 is supplied to the second oil hole 92.

[0153] Figure 21 is a cross-sectional view showing the oil supply path to the bearing in a comparative example. Figure 21 shows the cross-sectional shapes of the housing 50 and the outer ring 76 cut by a plane perpendicular to a predetermined axis 101.

[0154] Referring to Figure 21, in this comparative example, the housing 50 (housing body 51) is provided with an oil hole 421 and a circumferential groove 423. The circumferential groove 423 is recessed from the inner circumferential surface 50d of the housing 50 and has a groove shape that circumfers around a predetermined axis 101. The oil hole 421 extends in the radial direction of the main shaft 21. The oil hole 421 extends between the oil supply hole 90 and the circumferential groove 423.

[0155] The outer ring 76 is provided with an oil hole 422. The oil hole 422 extends radially along the spindle 21. The end of the oil hole 422 on the radially outer side of the spindle 21 communicates with the circumferential groove 423. The angular position of the oil hole 422 in the circumferential direction of the spindle 21 may be offset from the angular position of the oil hole 421 in the circumferential direction of the spindle 21.

[0156] On each side of the circumferential groove 423 in the axial direction of the predetermined shaft 101, a sealing groove is provided, which is recessed from the inner circumferential surface 50d of the housing 50 and forms a groove shape that circumfers around the predetermined shaft 101. An annular sealing member is arranged in the sealing groove and circumfers around the predetermined shaft 101.

[0157] In such comparative examples, the volume of the passage through which oil-air flows is significantly expanded in the circumferential groove 423 that connects oil holes 421 and 422. In this case, some of the oil may separate from the oil-air as it passes through the circumferential groove 423. Since the liquefied oil cannot enter the oil hole 422 from the circumferential groove 423, the amount of oil reaching the bearing decreases.

[0158] In contrast, in this embodiment, since the sealing groove 93 has a circular opening shape when viewed in the radial direction of the main shaft 21, the volume of the passage through which the oil air passes does not expand significantly in the sealing groove 93 between the first oil hole 91 and the second oil hole 92, compared to the comparative example above. As a result, the separation of some of the oil from the oil air in the sealing groove 93 is suppressed, and oil can be supplied to the first bearing group 71 more efficiently.

[0159] To summarize the configuration of the spindle device 10 in Embodiment 3 of this invention, the spindle device 10 in this embodiment comprises a spindle 21, a housing 50 that houses the spindle 21 and includes an inner circumferential surface 50d, a sealing groove 93 that is recessed from the inner circumferential surface 50d and has a circular opening shape when viewed in the radial direction of the spindle 21, and a first oil hole 91 that opens at the bottom 93a of the sealing groove 93 and into which oil conveyed by air flows, and an outer ring 76 that has an outer circumferential surface 76a, and has a second oil hole 92 that opens on the outer circumferential surface 76a opposite to the opening of the sealing groove 93 on the inner circumferential surface 50d and into which oil from the first oil hole 91 is supplied, and a first bearing group 71 (71A, 71B) that is arranged between the spindle 21 and the housing 50 in the radial direction of the spindle 21 as bearings, and an annular sealing member 96 arranged in the sealing groove 93.

[0160] With this configuration, as described above, oil can be supplied more efficiently to the first bearing group 71.

[0161] Furthermore, the outer ring 76 is provided with a second wiring groove 82 that is recessed from the outer circumferential surface 76a of the outer ring 76 and extends in the axial direction of the spindle 21. The spindle device 10 further includes a first wiring 210 arranged in the second wiring groove 82. The sealing groove 93 is provided at an angular position offset from the second wiring groove 82 in the circumferential direction of the spindle 21.

[0162] With this configuration, the second wiring groove 82 and the first wiring 210 positioned in the second wiring groove 82 are prevented from extending across the sealing member 96 positioned in the sealing groove 93 in the axial direction of the main shaft 21. As a result, the sealing member 96 can be brought into close contact with the outer circumferential surface 76a of the outer ring 76, thereby ensuring sufficient sealing performance by the sealing member 96 in the oil passage between the first oil hole 91 and the second oil hole 92.

[0163] Furthermore, the outer ring 76 is provided with an anti-rotation groove 86 that is recessed from the outer circumferential surface 76a of the outer ring 76 and extends in the axial direction of the spindle 21. The spindle device 10 is provided in the housing 50 and further includes an anti-rotation mechanism 310 that abuts against the bottom of the anti-rotation groove 86 in the radial direction of the spindle 21. The sealing groove 93 is provided at an angular position offset from the anti-rotation groove 86 in the circumferential direction of the spindle 21.

[0164] With this configuration, the anti-rotation groove 86 can be prevented from extending across the sealing member 96 positioned in the sealing groove 93 in the axial direction of the main shaft 21. As a result, the sealing member 96 can be brought into close contact with the outer circumferential surface 76a of the outer ring 76, thereby ensuring sufficient sealing performance by the sealing member 96 in the oil passage between the first oil hole 91 and the second oil hole 92.

[0165] Furthermore, the first bearing group 71 includes a first bearing 71A and a second bearing 71B that is aligned with the first bearing 71A in the axial direction of the main spindle 21. The outer ring 76 is further provided with a connecting groove 88 that is recessed from the outer circumferential surface 76a of the outer ring 76 and extends axially across the main spindle 21 between the first bearing 71A and the second bearing 71B. The spindle device 10 further includes a connecting pin 331 positioned in the connecting groove 88. The sealing groove 93 is provided at an angular position offset from the connecting groove 88 in the circumferential direction of the main spindle 21.

[0166] With this configuration, the connecting groove 88 and the connecting pin 331 positioned in the connecting groove 88 are prevented from extending across the sealing member 96 positioned in the sealing groove 93 in the axial direction of the main shaft 21. As a result, the sealing member 96 can be brought into close contact with the outer circumferential surface 76a of the outer ring 76, thereby ensuring sufficient sealing performance by the sealing member 96 in the oil passage between the first oil hole 91 and the second oil hole 92.

[0167] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0168] 10 Spindle unit, 11 Spindle base, 12 Bed, 14 Column, 16 Table, 21 Spindle, 23 Collet, 24 Drawbar, 25 Disc spring, 26 Unclamp cylinder, 27 Enlarged diameter section, 28, 326 Threaded section, 31 Rotor, 32 Stator, 33 Motor housing, 41 Front cover, 42 Nut, 43 Cover, 45 Rear housing, 46 Ring, 50 Housing, 50a First end face, 50b Second end face, 50c, 76a Outer circumference, 50d Inner circumference, 51 Housing body, 53 Front section, 54 Middle section, 55 Rear section, 56, 63 Flange section, 56a End face, 61 Sleeve, 62 Cylindrical section, 66, 312 Elastic member, 71 First bearing group, 71A First bearing, 71B 72 Second bearing, 72C Second bearing group, 72D Third bearing, 73 Third bearing group, 76 Outer ring, 77 Inner ring, 78 Rolling element, 79 Cage, 81 First groove for wiring, 82 Second groove for wiring, 83 Third groove for wiring, 86 Anti-rotation groove, 88 Connecting groove, 90, 90A, 90B Oil supply hole, 91, 91A, 91B First hole for oil, 92, 92A, 92B Second hole for oil, 93, 93A, 93B Seal groove, 93a Groove bottom, 96 Seal member, 100 Machine tool, 101 Designated shaft, 110 First internal space, 120 Second internal space, 210, 210A, 210B First wiring, 220 Second wiring, 241 First hole for wiring, 242 243 Second wiring hole, 310, 310A, 310B Third wiring hole, 311 Anti-rotation mechanism, 311 Pin, 313 Bolt, 316 Shaft, 317 Head, 321 First anti-rotation hole, 322 Second anti-rotation hole, 327 Cover, 331 Connecting pin, 410 Mixing valve, 421, 422 Oil holes, 423 Circumferential groove.

Claims

1. The main shaft, A housing for the aforementioned spindle, A bearing having an outer ring and positioned between the main shaft and the housing, It comprises an anti-rotation mechanism having an elastic member, provided in the housing, and the anti-rotation mechanism elastically contacting the outer ring due to the elastic deformation of the elastic member, The anti-rotation mechanism is mounted to the housing so as to be slidable in the radial direction of the main shaft, and further has a pin that contacts the outer ring in the radial direction of the main shaft, The spindle device of a machine tool is provided such that the elastic member, by elastically deforming, imparts an elastic force to the pin directed radially inward of the spindle.

2. The spindle device of a machine tool according to claim 1, wherein the anti-rotation mechanism is provided at a single angular position in the circumferential direction of the spindle.

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