Spindle lubrication device for machine tool, machine tool, and method for using machine tool

Abstract

This spindle lubrication device for a machine tool comprises: a rotating body that holds a tool; a plurality of bearings; a housing; a mixed fluid supply device; and a recovery device that recovers an oil-containing fluid. The recovery device is equipped with a plurality of recovery flow paths, a plurality of ejectors, and a plurality of flow rate control valves. The plurality of ejectors include: a first ejector that suctions a first oil-containing fluid from a first recovery flow path by generating a negative pressure using first air supplied from a first air flow path; and a second ejector that suctions a second oil-containing fluid from a second recovery flow path by generating a negative pressure using second air supplied from a second air flow path. The plurality of flow rate control valves include: a first flow rate control valve that adjusts the flow rate of the first air supplied from the first air flow path to the first ejector; and a second flow rate control valve that adjusts the flow rate of the second air supplied from the second air flow path to the second ejector.

Description

Machine tool spindle lubrication device, machine tool, and method of using machine tool

[0001] The present invention relates to a spindle lubrication device for a machine tool, a machine tool, and a method for using the machine tool.

[0002] A lubrication device for a spindle of a machine tool is known.

[0003] As a related technique, Patent Document 1 discloses a spindle lubrication device. In the spindle lubrication device described in Patent Document 1, a rotating shaft is rotatably supported in a housing via bearings, and the bearings are lubricated with lubricating oil supplied from the outside. In the spindle lubrication device described in Patent Document 1, the discharged oil is either vacuum-sucked by a negative pressure generating device or collected by natural fall.

[0004] Japanese Patent Application Laid-Open No. 2016-002622

[0005] An object of the present invention is to provide a technique for preventing poor lubrication in each of a plurality of bearings.

[0006] In some embodiments, a spindle lubrication device for a machine tool includes a rotating body that holds a tool, a plurality of bearings including a first bearing and a second bearing, a housing that rotatably supports the rotating body around a first axis via the plurality of bearings, a mixed fluid supply device that supplies a mixed fluid containing oil and air to the plurality of bearings, and a recovery device that recovers the oil-containing fluid. The recovery device includes a plurality of recovery passages that are provided in the housing and recover the oil-containing fluid from the plurality of bearings, a plurality of ejectors that are arranged outside the housing, and a plurality of flow control valves. The plurality of recovery passages include a first recovery passage that recovers a first oil-containing fluid discharged mainly from at least one bearing including the first bearing, and a second recovery passage that recovers a second oil-containing fluid discharged mainly from at least one bearing including the second bearing. The plurality of ejectors include a first ejector that sucks the first oil-containing fluid from the first recovery passage by generating a negative pressure with a first air supplied from a first air passage, and a second ejector that sucks the second oil-containing fluid from the second recovery passage by generating a negative pressure with a second air supplied from a second air passage. The plurality of flow control valves include a first flow control valve that adjusts the flow rate of the first air supplied to the first ejector from the first air passage, and a second flow control valve that adjusts the flow rate of the second air supplied to the second ejector from the second air passage.

[0007] In some embodiments, the machine tool includes a machining head having a rotating body for holding a tool, a plurality of bearings including a first bearing and a second bearing, a housing for rotatably supporting the rotating body via the plurality of bearings, a first rotation drive device for rotating the rotating body about a first axis, a fluid mixture supplying device for supplying a fluid mixture containing oil and air to the plurality of bearings, a recovery device for recovering the oil-containing fluid containing the oil, a workpiece support device for supporting a workpiece, a moving device for moving the machining head relative to the workpiece support device, and a control device for controlling at least the first rotation drive device, the fluid mixture supplying device, and the moving device. The recovery device is provided in the housing and includes a plurality of recovery passages for recovering the oil-containing fluid from the plurality of bearings, a plurality of ejectors arranged outside the housing, and a plurality of flow control valves. The plurality of recovery passages include a first recovery passage that mainly recovers a first oil-containing fluid discharged from at least one bearing including the first bearing, and a second recovery passage that mainly recovers a second oil-containing fluid discharged from at least one bearing including the second bearing. The plurality of ejectors include a first ejector that generates a negative pressure using first air supplied from a first air passage to suck the first oil-containing fluid from the first recovery passage, and a second ejector that generates a negative pressure using second air supplied from a second air passage to suck the second oil-containing fluid from the second recovery passage. The plurality of flow control valves include a first flow control valve that adjusts the flow rate of the first air supplied from the first air passage to the first ejector, and a second flow control valve that adjusts the flow rate of the second air supplied from the second air passage to the second ejector.

[0008] A method of using the machine tool in some embodiments is the method of using the machine tool described above, and the method of using the machine tool includes the steps of: under a second condition in which the plurality of conduits are fluidly separated from the plurality of recovery passages and the mixed fluid is supplied from the fluid mixture supply device to the plurality of bearings at a first flow rate, when a flow rate of the first oil-containing fluid discharged from the first recovery passage to an outside of the first recovery passage is defined as a first discharge flow rate, deriving the first discharge flow rate by measurement or simulation; and under the second condition in which the plurality of conduits are fluidly connected to the plurality of recovery passages, respectively, and when a flow rate of the first oil-containing fluid flowing through the first conduit is defined as a first discharge flow rate, deriving the second discharge flow rate by measurement or simulation. the flow rate of the second oil-containing fluid flowing through the second pipeline under the first condition is defined as a second recovery flow rate, the step of deriving the second recovery flow rate by measurement or simulation, the step of deriving a first aperture of the first flow control valve such that a ratio of the first recovery flow rate to the first discharge flow rate is within a predetermined range, the step of deriving a second aperture of the second flow control valve such that a ratio of the second recovery flow rate to the second discharge flow rate is within a predetermined range, the step of supplying the mixed fluid to the plurality of bearings using the mixed fluid supply device, the step of operating the recovery device in a state in which the aperture of the first flow control valve is set to the first aperture and the aperture of the second flow control valve is set to the second aperture, and the step of machining the workpiece with the tool held by the rotating body and rotating around the first axis.

[0009] The present invention can provide a technique for preventing poor lubrication in each of a plurality of bearings.

[0010] FIG. 1 is a schematic cross-sectional view showing a spindle lubrication device for a machine tool according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing a spindle lubrication device for a machine tool according to a comparative example. FIG. 3 is a schematic cross-sectional view showing a spindle lubrication device for a machine tool according to a first modified example of the first embodiment. FIG. 4 is a diagram showing a state in which a first recovery flow rate and a second recovery flow rate are measured. FIG. 5 is a diagram showing a state in which an oil-containing fluid is discharged from the first recovery passage and the second recovery passage to the outside of a housing. FIG. 6 is a schematic cross-sectional view showing a spindle lubrication device for a machine tool according to the first embodiment. FIG. 7 is a schematic cross-sectional view showing a spindle lubrication device for a machine tool according to a second embodiment. FIG. 8 is a diagram showing a state in which a first recovery flow rate and a second recovery flow rate are measured. FIG. 9 is a diagram showing a state in which an oil-containing fluid is discharged from the first recovery passage and the second recovery passage to the outside of a housing. FIG. 10 is a schematic cross-sectional view showing a main spindle lubrication device of a machine tool according to a second embodiment. FIG. 11 is a schematic cross-sectional view showing a portion of the main spindle lubrication device of a machine tool according to the second embodiment. FIG. 12 is a diagram for explaining an example of the structure of an ejector. FIG. 13 is a schematic cross-sectional view showing a main spindle lubrication device of a machine tool according to a first modified example of the second embodiment. FIG. 14 is a schematic cross-sectional view showing a portion of the main spindle lubrication device of a machine tool according to the first modified example of the second embodiment. FIG. 15 is a diagram showing a state in which a first recovery flow rate and a second recovery flow rate are measured. FIG. 16 is a diagram showing a state in which oil-containing fluid is discharged from the first recovery passage, the second recovery passage, and the third recovery passage to the outside of the housing. FIG. 17 is a schematic cross-sectional view showing a main spindle lubrication device of a machine tool according to a first modified example of the second embodiment. FIG. 18 is a diagram showing a portion of the main spindle lubrication device of a machine tool according to the first modified example of the second embodiment. Fig. 19 is a schematic cross-sectional view showing an example of a machining head. Fig. 20 is a schematic cross-sectional view showing a part of a spindle lubrication device of a machine tool in a first modified example of the second embodiment. Fig. 21 is a schematic cross-sectional view showing a part of a spindle lubrication device of a machine tool in a first modified example of the second embodiment.FIG. 22 is a schematic cross-sectional view showing a portion of a spindle lubrication device of a machine tool in a first modified example of the second embodiment. FIG. 23 is a schematic cross-sectional view showing a portion of a spindle lubrication device of a machine tool in a second modified example of the second embodiment. FIG. 24 is a schematic cross-sectional view showing a portion of a spindle lubrication device of a machine tool in a first modified example of the second embodiment. FIG. 25 is a schematic cross-sectional view showing a portion of a spindle lubrication device of a machine tool in a first modified example of the second embodiment. FIG. 26 is a diagram for explaining a first annular groove and a second annular groove. FIG. 27 is a schematic perspective view showing a schematic example of a machine tool in a third embodiment. FIG. 28 is a schematic perspective view showing another example of a machine tool in the third embodiment. FIG. 29 is a diagram showing a state in which a control device can control a plurality of control-target devices. FIG. 30 is a diagram for explaining an example of an arrangement of a collection container. FIG. 31 is a diagram for explaining another example of an arrangement of a collection container. FIG. 32 is a flowchart showing an example of a method of using a machine tool in an embodiment.

[0011] Hereinafter, a machine tool spindle lubrication device 1, a machine tool 100, and a method of using the machine tool according to an embodiment will be described with reference to the drawings. In the following description of the embodiment, parts and members having the same functions are given the same reference numerals, and repeated description of parts and members given the same reference numerals will be omitted.

[0012] (Definition of direction) In this specification, the direction from the rear end 22 of the rotating body 2 toward the front end 24 of the rotating body 2 is defined as the "first direction DR1," and the direction opposite to the first direction DR1 is defined as the "second direction DR2."

[0013] In this specification, the direction approaching the first axis AX1, which is the rotation axis of the rotor 2, is defined as the "radially inward direction DR3" or "inward." Furthermore, the direction away from the first axis AX1, which is the rotation axis of the rotor 2, is defined as the "radially outward direction DR4" or "outward."

[0014] The direction from the rear end 22 of the rotating body 2 toward the front end 24 of the rotating body 2 is, for example, downward or sideways. If the posture of the machining head 10 is changeable, the direction from the rear end 22 of the rotating body 2 toward the front end 24 of the rotating body 2 changes according to the change in posture of the machining head 10. In this specification, regardless of the actual posture of the machining head 10, the direction from the rear end 22 of the rotating body 2 toward the front end 24 of the rotating body is referred to as the "downward direction," and the direction from the front end 24 of the rotating body 2 toward the rear end 22 of the rotating body is referred to as the "upward direction." Furthermore, in this specification, regardless of the actual posture of the machining head 10, the surface on the first direction DR1 side is referred to as the "lower surface," and the surface on the second direction DR2 side is referred to as the "upper surface."

[0015] (First embodiment) A spindle lubrication device 1A of a machine tool in a first embodiment will be described with reference to Figs. 1 to 6. Fig. 1 is a schematic cross-sectional view showing the spindle lubrication device 1A of a machine tool in the first embodiment. Fig. 2 is a schematic cross-sectional view showing the spindle lubrication device 1A' of a machine tool in a comparative example. Fig. 3 is a schematic cross-sectional view showing the spindle lubrication device 1A of a machine tool in a first modified example of the first embodiment. Fig. 4 is a diagram showing a state in which a first recovery flow rate and a second recovery flow rate are measured. Fig. 5 is a diagram showing a state in which an oil-containing fluid is discharged from a first recovery passage 71 and a second recovery passage 72 to the outside of a housing 4. Fig. 6 is a schematic cross-sectional view showing the spindle lubrication device 1A of a machine tool in the first embodiment.

[0016] 1 , the spindle lubrication device 1A of a machine tool in the first embodiment includes a rotating body 2 that holds a tool T, a plurality of bearings 3, a housing 4, a mixed fluid supplying device 6, and a recovery device 7. The spindle lubrication device 1A of a machine tool may include a controller 8 that controls at least the mixed fluid supplying device 6.

[0017] In the example shown in FIG. 1 , the rotating body 2 is a rotating shaft 20. The rotating body 2 is rotatable around a first axis AX1. The rotating body 2 (more specifically, the rotating shaft 20) has a rear end 22 and a tip end portion 24 that holds a tool T. Note that a tool holder HD that holds the tool T may be attached to the tip end portion 24. In this case, the tool T is held by the tip end portion 24 via the tool holder HD. Therefore, in this specification, the "tip end portion 24 that holds a tool" includes both a tip end portion 24 that directly holds the tool T and a tip end portion 24 that holds the tool T via the tool holder HD. In other words, in this specification, the tip end portion 24 may be configured to directly hold the tool T, or may be configured to hold the tool T via the tool holder HD.

[0018] The housing 4 supports the rotating body 2 rotatably about the first axis AX1 via a plurality of bearings 3. In the example shown in Fig. 1, the housing 4 is formed by assembling a plurality of parts.

[0019] 1, the main shaft lubrication device 1A includes a plurality of bearings 3 including a first bearing 31a and a second bearing 36b. In the example shown in Fig. 1, the first bearing 31a is a front bearing 31 that supports the tip end 24 of the rotating body 2. The second bearing 36b is a rear bearing 36 that supports the rear end 22 of the rotating body 2. Alternatively, the second bearing 36b may be a bearing that supports an intermediate portion of the rotating body.

[0020] In the example shown in Fig. 1 , the main spindle lubrication device 1A of the machine tool includes a front bearing 31 that supports the front end 24 of the rotating body 2, and a rear bearing 36 that supports the rear end 22 of the rotating body 2. The front bearing 31 has at least one bearing including a first bearing 31a. The front bearing 31 may also have the first bearing 31a and a third bearing 31c. In the example shown in Fig. 1 , the rear bearing 36 has at least one bearing including a second bearing 36b. The rear bearing 36 may also have multiple bearings including the second bearing 36b.

[0021] The mixed fluid supply device 6 supplies a mixed fluid containing oil and air to the multiple bearings 3. This mixed fluid is sometimes called oil-air. In oil-air, the oil is carried by the air. In other words, in oil-air, the air functions as a carrier fluid that carries the oil. More specifically, by supplying oil-air to the multiple bearings 3, a small amount of oil is continuously supplied to the multiple bearings 3 using the flow of compressed air.

[0022] The recovery device 7 recovers an oil-containing fluid that contains oil. In the example shown in Fig. 1 , the recovery device 7 includes a plurality of recovery flow paths (71, 72) provided in the housing 4, a plurality of ejectors (75a, 75b) arranged outside the housing 4, and a plurality of flow control valves (76a, 76b). The recovery device 7 may include a plurality of pipes (74a, 74b) that fluidly connect the plurality of recovery flow paths (71, 72) and the plurality of ejectors (75a, 75b). Alternatively, when the plurality of recovery flow paths (71, 72) and the plurality of ejectors (75a, 75b) are directly connected, the plurality of pipes (74a, 74b) are omitted.

[0023] The plurality of recovery passages (71, 72) are provided in the housing 4 and recover oil-containing fluid from the plurality of bearings 3. In the example shown in Figure 1, the plurality of recovery passages (71, 72) include a first recovery passage 71 and a second recovery passage 72.

[0024] The first recovery passage 71 is provided in the housing 4 and mainly recovers the oil-containing fluid discharged from at least one bearing including the first bearing 31a. Hereinafter, the oil-containing fluid recovered via the first recovery passage 71 will be referred to as the "first oil-containing fluid." In the example shown in FIG. 1 , the first recovery passage 71 mainly recovers the first oil-containing fluid discharged from the front bearing 31. In the example shown in FIG. 1 , all or most of the first recovery passage 71 is disposed within the housing 4. All or most of the first recovery passage 71 may be constituted by a through-hole formed in the housing 4.

[0025] The second recovery passage 72 is provided in the housing 4 and mainly recovers the oil-containing fluid discharged from at least one bearing including the second bearing 36b. Hereinafter, the oil-containing fluid recovered via the second recovery passage 72 will be referred to as the "second oil-containing fluid." In the example shown in FIG. 1 , the second recovery passage 72 mainly recovers the second oil-containing fluid discharged from the rear bearing 36. In the example shown in FIG. 1 , all or most of the second recovery passage 72 is disposed within the housing 4. All or most of the second recovery passage 72 may be constituted by a through-hole formed in the housing 4. In the example shown in FIG. 1 , the second recovery passage 72 is a passage separate from the first recovery passage 71.

[0026] In the example shown in FIG. 1, the multiple pipelines (74a, 74b) include a first pipeline 74a and a second pipeline 74b.

[0027] The first conduit 74a fluidly connects the first recovery passage 71 and a first ejector 75a disposed outside the housing 4. In the example shown in Fig. 1 , the entire first conduit 74a is disposed outside the housing 4. Alternatively, a portion of the first conduit 74a may be disposed inside the housing 4, and a majority of the first conduit 74a may be disposed outside the housing 4. In the example shown in Fig. 1 , the first ejector 75a is an ejector that is one-to-one associated with the first recovery passage 71 via the first conduit 74a.

[0028] The second conduit 74b fluidly connects the second recovery passage 72 and a second ejector 75b disposed outside the housing 4. In the example shown in Fig. 1 , the entire second conduit 74b is disposed outside the housing 4. Alternatively, a portion of the second conduit 74b may be disposed inside the housing 4, and a majority of the second conduit 74b may be disposed outside the housing 4. In the example shown in Fig. 1 , the second ejector 75b is an ejector that is one-to-one associated with the second recovery passage 72 via the second conduit 74b.

[0029] The plurality of ejectors (75a, 75b) are disposed outside the housing. In the example shown in Fig. 1, the plurality of ejectors (75a, 75b) include a first ejector 75a and a second ejector 75b.

[0030] The first ejector 75a generates negative pressure using air supplied from the first air flow path 77a, thereby sucking the first oil-containing fluid from the first recovery flow path 71. Hereinafter, the air supplied from the first air flow path 77a to the first ejector 75a will be referred to as "first air." In the example shown in Fig. 1, the first ejector 75a generates negative pressure in the first pipe 74a using the first air supplied from the first air flow path 77a, and sucks the first oil-containing fluid from the first recovery flow path 71 via the first pipe 74a.

[0031] The second ejector 75b generates negative pressure using air supplied from the second air flow path 77b, thereby sucking the second oil-containing fluid from the second recovery flow path 72. Hereinafter, the air supplied from the second air flow path 77b to the second ejector 75b will be referred to as "second air." In the example shown in Fig. 1, the second ejector 75b generates negative pressure in the second pipe 74b using the second air supplied from the second air flow path 77b, and sucks the second oil-containing fluid from the second recovery flow path 72 via the second pipe 74b.

[0032] 1, the plurality of flow control valves (76a, 76b) include a first flow control valve 76a and a second flow control valve 76b. The first flow control valve 76a adjusts the flow rate of the first air supplied from the first air flow path 77a to the first ejector 75a. The second flow control valve 76b adjusts the flow rate of the second air supplied from the second air flow path 77b to the second ejector 75b.

[0033] 1 , the controller 8 transmits a control command to the mixed fluid supply device 6, and the mixed fluid supply device 6, upon receiving the control command, supplies a mixed fluid containing oil and air (more specifically, oil-air) to the plurality of bearings 3. Additionally, the controller 8 may control the recovery device 7. More specifically, the controller 8 transmits a control command to the recovery device 7, and the recovery device 7, upon receiving the control command, recovers an oil-containing fluid containing oil.

[0034] In the comparative example of a spindle lubrication device 1A' (see FIG. 2 ) for a machine tool, multiple bearings 3 are fluidly connected to a single negative pressure generator 75' via a conduit 74. In the example shown in FIG. 2 , the flow rate of the oil-containing fluid recovered from the multiple bearings 3 cannot be adjusted for each bearing or for each group of bearings. Therefore, it is difficult to prevent poor lubrication in each of the multiple bearings. For example, in the example shown in FIG. 2 , assume that the second bearing 36b is adequately lubricated and the first bearing 31a is not sufficiently lubricated. In this case, oil may leak from the gap between the housing 4 and the rotating body 2. Therefore, to prevent this leakage, it is necessary to increase the suction volume of the negative pressure generator 75'. However, increasing the suction volume of the negative pressure generator 75' would result in excessive recovery of the oil-containing fluid from the second bearing 36b, resulting in poor lubrication of the second bearing 36b.

[0035] 2, consider a case where the number of bearings included in the front bearing 31 is different from the number of bearings included in the rear bearing 36. Alternatively, or additionally, consider a case where the length of the first conduit 74a is different from the length of the second conduit 74b. In such a case, if equal suction forces are applied to the first conduit 74a and the second conduit 74b to prevent oil leakage from all bearings, poor lubrication of the bearings becomes even more likely.

[0036] In contrast, the spindle lubrication device 1A of a machine tool in the first embodiment includes a plurality of ejectors including a first ejector 75a and a second ejector 75b, and a plurality of flow control valves including a first flow control valve 76a that adjusts the flow rate of the first air supplied to the first ejector 75a, and a second flow control valve 76b that adjusts the flow rate of the second air supplied to the second ejector 75b.

[0037] Therefore, by adjusting the flow rate of the first air and the flow rate of the second air, it is possible to adjust the flow rate of the oil-containing fluid recovered for each bearing or for each bearing group, thereby preventing poor lubrication in each of the multiple bearings 3.

[0038] Furthermore, in the first embodiment, oil leakage around the machining head 10 is suppressed, and contamination of the work environment by oil is prevented or suppressed, thereby improving the work environment and reducing the burden on the environment.

[0039] (Optional Additional Configuration) Next, optional additional configurations that can be employed in the machine tool spindle lubrication device 1A in the first embodiment will be described with reference to FIGS. 1 to 6.

[0040] (Air Source AS) In the example shown in Fig. 1, the machine tool spindle lubrication device 1A has at least one air source AS (e.g., an air compressor). The at least one air source AS supplies first air to the first air flow path 77a and supplies second air to the second air flow path 77b. In the example shown in Fig. 1, the air source AS1 that supplies the first air to the first air flow path 77a and the air source AS2 that supplies the second air to the second air flow path 77b are the same. Alternatively, the air source AS2 that supplies the second air to the second air flow path 77b may be a different air source from the air source AS1 that supplies the first air to the first air flow path 77a.

[0041] 1, the recovery device 7 has a first air flow path 77a that supplies first air to the first ejector 75a, and a second air flow path 77b that supplies second air to the second ejector 75b. In the example shown in Fig. 1, a first flow control valve 76a is arranged in the first air flow path 77a, and a second flow control valve 76b is arranged in the second air flow path 77b.

[0042] (Main air flow path 12) In the example shown in Fig. 1, the machine tool spindle lubricating device 1A has a main air flow path 12 that fluidly connects the air source AS to the first air flow path 77a and the second air flow path 77b. In the example shown in Fig. 1, the main air flow path 12 is branched into a plurality of air flow paths including the first air flow path 77a and the second air flow path 77b.

[0043] (On-off valve 13) In the example shown in Fig. 1, the machine tool spindle lubrication device 1A has an on-off valve 13 arranged between the air source AS and the first flow rate control valve 76a. When the on-off valve 13 is in a closed state, air is not supplied to the first flow rate control valve 76a. In the example shown in Fig. 1, the on-off valve 13 is arranged in the main air flow path 12. In this case, when the on-off valve 13 is in an open state, air is supplied to the first flow rate control valve 76a and the second flow rate control valve 76b, and when the on-off valve 13 is in a closed state, air is not supplied to the first flow rate control valve 76a and the second flow rate control valve 76b.

[0044] Alternatively, as illustrated in Fig. 3, the spindle lubrication device 1A of a machine tool may include a first on-off valve 13a arranged between the air source AS and the first flow control valve 76a, and a second on-off valve 13b arranged between the air source AS and the second flow control valve 76b. In the example illustrated in Fig. 3, the first on-off valve 13a is arranged in the first air flow path 77a, and the second on-off valve 13b is arranged in the second air flow path 77b. In this case, when the first on-off valve 13a is open, air is supplied to the first flow control valve 76a, and when the first on-off valve 13a is closed, air is not supplied to the first flow control valve 76a. Furthermore, when the second on-off valve 13b is open, air is supplied to the second flow control valve 76b, and when the second on-off valve 13b is closed, air is not supplied to the second flow control valve 76b.

[0045] 1 , the recovery device 7 includes the exhaust pipe 78 and a recovery container 792. Additionally, the recovery device 7 may include an exhaust cleaner 791.

[0046] The exhaust pipe 78 receives exhaust (more specifically, oil-containing fluid) from the plurality of ejectors (75 a, 75 b). In the example shown in FIG. 1, the exhaust pipe 78 fluidly connects the plurality of ejectors (75 a, 75 b) to an exhaust cleaner 791. The exhaust pipe 78 is formed, for example, by a plurality of pipes.

[0047] The collection container 792 is fluidly connected to the exhaust line 78. In the example shown in Figure 1, the collection container 792 receives liquid oil contained in the oil-containing fluid from the exhaust line 78 via the exhaust cleaner 791. Alternatively, the collection container 792 may receive the oil-containing fluid directly from the exhaust line 78 without passing through the exhaust cleaner 791.

[0048] 1 , the exhaust cleaner 791 receives the oil-containing fluid from the multiple ejectors (75 a, 75 b) via the exhaust pipe 78. The exhaust cleaner 791 also separates the oil-containing fluid received from the exhaust pipe 78 into liquid oil and air. The liquid oil separated from the oil-containing fluid by the exhaust cleaner 791 is collected in a collection container 792.

[0049] 1, most of the oil used to lubricate the multiple bearings 3 is collected in a collection container 792 via an exhaust cleaner 791. This prevents or suppresses contamination of the area around the machining head 10 with oil, thereby improving the working environment and reducing the burden on the environment.

[0050] Second Embodiment A main spindle lubrication device 1B of a machine tool according to a second embodiment will be described with reference to Figs. 7 to 26. Fig. 7 is a schematic cross-sectional view showing a main spindle lubrication device 1B of a machine tool according to the second embodiment. Fig. 8 is a diagram showing a schematic view of how a first recovery flow rate and a second recovery flow rate are measured. Fig. 9 is a diagram showing a schematic view of how an oil-containing fluid is discharged from a first recovery passage 71 and a second recovery passage 72 to the outside of the housing 4. Fig. 10 is a schematic cross-sectional view showing a main spindle lubrication device 1B of a machine tool according to the second embodiment. Fig. 11 is a schematic cross-sectional view showing a portion of a main spindle lubrication device 1B of a machine tool according to the second embodiment. Fig. 12 is a diagram for explaining an example of the structure of an ejector 75. Fig. 13 is a schematic cross-sectional view showing a main spindle lubrication device 1B of a machine tool according to a first modified example of the second embodiment. FIG. 14 is a schematic cross-sectional view showing a portion of a spindle lubrication device 1B of a machine tool in a first modified example of the second embodiment. FIG. 15 is a diagram showing a state in which a first recovery flow rate and a second recovery flow rate are measured. FIG. 16 is a diagram showing a state in which an oil-containing fluid is discharged from the first recovery passage 71, the second recovery passage 72, and the third recovery passage 73 to the outside of the housing 4. FIG. 17 is a schematic cross-sectional view showing a portion of a spindle lubrication device 1B of a machine tool in a first modified example of the second embodiment. FIG. 18 is a diagram showing a portion of a spindle lubrication device 1B of a machine tool in a first modified example of the second embodiment. FIG. 19 is a schematic cross-sectional view showing an example of a machining head 10. FIGS. 20 to 22, 24, and 25 are schematic cross-sectional views showing a portion of a spindle lubrication device 1B of a machine tool in a first modified example of the second embodiment. Fig. 23 is a schematic cross-sectional view showing a part of a spindle lubrication device 1B of a machine tool in a second modified example of the second embodiment. Fig. 26 is a diagram for explaining the first annular groove V1 and the second annular groove V2.

[0051] In the second embodiment, differences from the first embodiment will be mainly described. On the other hand, in the second embodiment, repeated descriptions of matters already described in the first embodiment will be omitted. Therefore, it goes without saying that matters already described in the first embodiment can be applied to the second embodiment even if they are not explicitly described in the second embodiment. Conversely, all matters described in the second embodiment can be applied to the first embodiment.

[0052] 7 , the spindle lubrication device 1B of the machine tool in the second embodiment includes: (1) a rotating body 2 that holds a tool T; (2) a plurality of bearings 3 including a first bearing 31 a and a second bearing 36 b; (3) a housing 4 that rotatably supports the rotating body 2 about a first axis AX1 via the plurality of bearings 3; (4) a mixed fluid supplying device 6 that supplies a mixed fluid containing oil and air to the plurality of bearings 3; and (5) a recovery device 7 that recovers an oil-containing fluid that contains oil. Additionally, the spindle lubrication device 1B of the machine tool may include a controller 8 that controls at least the mixed fluid supplying device 6. The recovery device 7 includes: (6A) a plurality of recovery passages (71, 72, 73) that are provided in the housing 4 and that recover the oil-containing fluid from the plurality of bearings 3; (6B) a plurality of ejectors (75a, 75b, 75c) that are arranged outside the housing 4; and (6C) a plurality of flow control valves (76a, 76b, 76c). Additionally, the recovery device 7 may include a plurality of conduits (74a, 74b, 74c) that fluidly connect the plurality of recovery channels (71, 72, 73) and the plurality of ejectors (75a, 75b, 75c).

[0053] In the example shown in Figure 7, the multiple recovery flow paths (71, 72, 73) include a first recovery flow path 71 that recovers a first oil-containing fluid discharged from at least one bearing, mainly including the first bearing 31a, and a second recovery flow path 72 that recovers a second oil-containing fluid discharged from at least one bearing, mainly including the second bearing 36b.

[0054] In the example shown in FIG. 7, the multiple pipelines (74a, 74b, 74c) include a first pipeline 74a that fluidly connects the first recovery passage 71 and the first ejector 75a, and a second pipeline 74b that fluidly connects the second recovery passage 72 and the second ejector 75b.

[0055] In the example shown in Figure 7, the multiple ejectors (75a, 75b, 75c) include a first ejector 75a that generates negative pressure in the first pipeline 74a by using first air supplied from a first air flow path 77a, and sucks in a first oil-containing fluid from the first recovery flow path 71 through the first pipeline 74a, and a second ejector 75b that generates negative pressure in the second pipeline 74b by using second air supplied from a second air flow path 77b, and sucks in a second oil-containing fluid from the second recovery flow path 72 through the second pipeline 74b.

[0056] In the example shown in FIG. 7 , the multiple flow control valves (76 a, 76 b, 76 c) include a first flow control valve 76 a that adjusts the flow rate of the first air supplied from the first air flow path 77 a to the first ejector 75 a, and a second flow control valve 76 b that adjusts the flow rate of the second air supplied from the second air flow path 77 b to the second ejector 75 b.

[0057] From the above, the machine tool spindle lubrication device 1B in the second embodiment has the same effects as the machine tool spindle lubrication device 1A in the first embodiment.

[0058] (Optional Additional Configuration) Next, with reference to FIGS. 1 to 26, optional additional configurations that can be employed in the machine tool spindle lubrication device 1B in the second embodiment (or the machine tool spindle lubrication device 1A in the first embodiment) will be described.

[0059] (Setting the first recovery flow rate, the first discharge flow rate, and the opening degree of the first flow control valve 76a) In each of Figures 4, 5, 8, and 9, it is assumed that the mixed fluid is supplied from the mixed fluid supply device 6 to the multiple bearings 3 at a first flow rate (see arrow AR1).

[0060] 4 and 8 show a state in which a plurality of conduits (74a, 74b, ...) are fluidly connected to a plurality of recovery flow paths (71, 72, ...). More specifically, in the examples shown in FIGS. 4 and 8, the first conduit 74a is fluidly connected to the first recovery flow path 71, and the second conduit 74b is fluidly connected to the second recovery flow path 72. In addition, in the example shown in FIG. 8, the third conduit 74c is fluidly connected to the third recovery flow path 73.

[0061] 5 and 9 show a state in which the multiple conduits (74a, 74b, ...) are fluidically separated from the multiple recovery flow paths (71, 72, ...). More specifically, in the examples shown in FIGS. 5 and 9, the first conduit 74a is fluidically separated from the first recovery flow path 71, and the second conduit 74b is fluidically separated from the second recovery flow path 72. In addition, in the example shown in FIG. 9, the third conduit 74c is fluidically separated from the third recovery flow path 73.

[0062] As illustrated in FIG. 4 or 8 , under a first condition CD1 in which a plurality of pipes (74a, 74b, ...) are fluidly connected to a plurality of recovery flow paths (71, 72, ...), respectively, and a first flow rate of the mixed fluid is supplied from the mixed fluid supply device 6 to a plurality of bearings 3, the flow rate of the first oil-containing fluid flowing through the first pipe 74a is defined as a first recovery flow rate (see arrow AR2 in FIGS. 4 and 8 ). The first recovery flow rate is derived, for example, by measurement. In the example illustrated in FIG. 4 or 8 , the spindle lubrication device 1 of the machine tool has a first flow meter 11a arranged in the first pipe 74a. In this case, the first recovery flow rate can be measured using the first flow meter 11a. Note that the first flow meter 11a may be removed from the first pipe 74a after the first recovery flow rate has been measured. Alternatively, the first flow meter 11a may remain attached to the first pipe 74a after measuring the first recovery flow rate.

[0063] As illustrated in FIG. 5 or FIG. 9 , under a second condition CD2 that differs from the above-described first condition CD1 only in that the multiple pipes (74a, 74b, ...) are fluidically separated from the multiple recovery passages (71, 72, ...), the flow rate of the first oil-containing fluid discharged from the first recovery passage 71 to the outside of the first recovery passage 71 (in the example illustrated in FIG. 5 or FIG. 9 , to the outside of the first recovery passage 71 and to the outside of the housing 4) is defined as a first discharge flow rate (see arrow AR4 in FIG. 5 or FIG. 9 ). The first discharge flow rate may be derived by measurement or simulation. For example, the first oil-containing fluid discharged from the first recovery passage 71 to the outside of the housing 4 may be recovered in a bag, and the first discharge flow rate may be derived by dividing the volume of the recovered first oil-containing fluid by the recovery time. Note that the measurement of the first discharge flow rate may be performed using another spindle lubrication device of the same type as the above-described spindle lubrication device 1 except that it does not have the recovery device 7.

[0064] The above-mentioned first condition CD1 may include a condition that the rotation angle of the rotating body 2 about the first axis AX1 relative to the housing 4 is maintained. In this case, the above-mentioned second condition CD2 includes a condition that the rotation angle of the rotating body 2 about the first axis AX1 relative to the housing 4 is maintained. Alternatively, the above-mentioned first condition CD1 may include a condition that the rotating body 2 rotates about the first axis AX1 relative to the housing 4 at a predetermined rotation speed (e.g., 20,000 rpm, or the maximum rotation speed in the design specifications of the spindle lubrication device, etc.). In this case, the above-mentioned second condition CD2 includes a condition that the rotating body 2 rotates about the first axis AX1 relative to the housing 4 at the predetermined rotation speed (e.g., 20,000 rpm, or the maximum rotation speed in the design specifications of the spindle lubrication device, etc.).

[0065] In the first condition CD1 described above, the flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 (i.e., the first flow rate) is equal to the flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 (i.e., the first flow rate) in the second condition CD2 described above. Assume that an upper limit value and a lower limit value of the flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 during operation of the spindle lubrication device 1 are predetermined. In this case, in each of the first condition CD1 and the second condition CD2 described above, the value of the first flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 is set to any value within a range not less than the above-mentioned lower limit value and not more than the above-mentioned upper limit value. In each of the first condition CD1 and the second condition CD2 described above, the value of the first flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 may be set to the above-mentioned upper limit value, may be set to the above-mentioned lower limit value, or may be set to a value smaller than the above-mentioned upper limit value and larger than the above-mentioned lower limit value.

[0066] 6 or 10 , the aperture of the first flow control valve 76 a is set so that the first recovery flow rate is within a range of 1 to 1.5 times the first discharge flow rate (more preferably, so that the first recovery flow rate is within a range of 1 to 1.2 times the first discharge flow rate). The aperture of the first flow control valve 76 a may be set manually or by the controller 8.

[0067] When the aperture of the first flow control valve 76a is set manually, the operator adjusts the aperture of the first flow control valve 76a while referring to the value of the first recovery flow rate indicated by the first flow meter 11a. In this manner, the operator manually sets the aperture of the first flow control valve 76a so that the first recovery flow rate is within a range of 1 to 1.5 times the first discharge flow rate. When the aperture of the first flow control valve 76a is set by the controller 8, the controller 8 may automatically adjust the aperture of the first flow control valve 76a so that the value of the first recovery flow rate indicated by the first flow meter 11a is within a range of 1 to 1.5 times the first discharge flow rate. After the first recovery flow rate is adjusted, the first flow meter 11a may be removed from the first conduit 74a or may remain attached to the first conduit 74a.

[0068] By making the first recovery flow rate at least one time the first discharge flow rate, insufficient recovery of the first oil-containing fluid is prevented. Thus, oil is prevented from leaking out of the machine tool spindle lubrication device 1 from the gap between the rotating body 2 and the housing 4. Furthermore, by making the first recovery flow rate at most 1.5 times the first discharge flow rate, excessive recovery of the first oil-containing fluid is prevented. Thus, poor lubrication does not occur in at least one bearing including the first bearing 31a.

[0069] (Setting the Second Recovery Flow Rate, the Second Discharge Flow Rate, and the Opening Degree of the Second Flow Control Valve 76b) As illustrated in FIG. 4 or FIG. 8, under the above-described first condition CD1, the flow rate of the second oil-containing fluid flowing through the second pipe 74b is defined as the second recovery flow rate (see arrow AR3 in FIGS. 4 and 8). The second recovery flow rate is derived, for example, by measurement. In the example illustrated in FIG. 4 or FIG. 8, the machine tool spindle lubrication device 1 has a second flow meter 11b arranged in the second pipe 74b. In this case, the second recovery flow rate can be measured using the second flow meter 11b. Note that the second flow meter 11b may be removed from the second pipe 74b after the second recovery flow rate has been measured. Alternatively, the second flow meter 11b may remain attached to the second pipe 74b after measuring the second recovery flow rate.

[0070] As exemplified in FIG. 5 or FIG. 9 , under the above-mentioned second condition CD2, the flow rate of the second oil-containing fluid discharged from the second recovery passage 72 to the outside of the second recovery passage 72 (outside the second recovery passage 72 and outside the housing 4 in the example shown in FIG. 5 or FIG. 9 ) is defined as the second discharge flow rate (see arrow AR5 in FIG. 5 or FIG. 9 ). The second discharge flow rate may be derived by measurement or simulation. For example, the second oil-containing fluid discharged from the second recovery passage 72 to the outside of the housing 4 may be recovered in a bag, and the second discharge flow rate may be derived by dividing the volume of the recovered second oil-containing fluid by the recovery time. Note that the measurement of the second discharge flow rate may be performed using another spindle lubrication device of the same type as the above-mentioned spindle lubrication device 1 except that it does not have the recovery device 7.

[0071] 6 or 10, the aperture of the second flow control valve 76b is set so that the second recovery flow rate is within a range of 1 to 1.5 times the second discharge flow rate (more preferably, so that the second recovery flow rate is within a range of 1 to 1.2 times the second discharge flow rate). The aperture of the second flow control valve 76b may be set manually or by the controller 8.

[0072] When the aperture of the second flow control valve 76b is set manually, the operator adjusts the aperture of the second flow control valve 76b while referring to the value of the second recovery flow rate indicated by the second flow meter 11b. In this manner, the operator manually sets the aperture of the second flow control valve 76b so that the second recovery flow rate is within a range of 1 to 1.5 times the second discharge flow rate. When the aperture of the second flow control valve 76b is set by the controller 8, the controller 8 may automatically adjust the aperture of the second flow control valve 76b so that the value of the second recovery flow rate indicated by the second flow meter 11b is within a range of 1 to 1.5 times the second discharge flow rate. Note that the second flow meter 11b may be removed from the second conduit 74b after the second recovery flow rate has been adjusted, or may remain attached to the second conduit 74b.

[0073] By setting the second recovery flow rate to be equal to or greater than the second discharge flow rate, insufficient recovery of the second oil-containing fluid is prevented. This prevents oil from leaking out of the machining head 10 from the gap between the rotating body 2 and the housing 4. Furthermore, by setting the second recovery flow rate to be equal to or less than 1.5 times the second discharge flow rate, excessive recovery of the second oil-containing fluid is prevented. This prevents poor lubrication of at least one bearing, including the second bearing 36b.

[0074] For example, if the lengths of the multiple pipes (74a, 74b, ...) are long or if the length of the exhaust pipe 78 is long, the pressure loss of the oil-containing fluid flowing through the pipes increases. In such cases, it is necessary to increase the suction force of the multiple ejectors (75a, 75b, ...). However, increasing the suction force of the multiple ejectors (75a, 75b, ...) can easily cause poor bearing lubrication. Furthermore, if the number of bearings included in the front bearing 31 is different from the number of bearings included in the rear bearing 36, or if the lengths of the first pipe 74a and the second pipe 74b are different, a lubrication imbalance can easily occur among the multiple bearings. In contrast, if the opening degrees of each of the first flow control valve 76a and the second flow control valve 76b are appropriately set as described above, poor lubrication can be prevented in each of the multiple bearings.

[0075] (Multiple Bearings 3) The multiple bearings 3 include a first bearing 31 a and a second bearing 36 b. Additionally, the multiple bearings 3 may include a third bearing 31 c. In the examples shown in Figures 6 and 10, the third bearing 31 c is disposed between the first bearing 31 a and the second bearing 36 b in the direction along the first axis AX1. The third bearing 31 c is, for example, a ball bearing.

[0076] The first bearing 31a constitutes at least a part of the front bearing 31 that supports the tip end 24 of the rotating body 2. The first bearing 31a is, for example, a ball bearing. In the example shown in FIGS. 6 and 10 , the first bearing 31a is the bearing that is arranged closest to the first direction DR1 (in other words, closest to the tip end) among the multiple bearings 3 that support the rotating body 2. The front bearing 31 that supports the tip end 24 of the rotating body 2 may include multiple bearings. In the example shown in FIGS. 6 and 10 , the front bearing 31 includes the first bearing 31a and a third bearing 31c.

[0077] 11, the first bearing 31a has an inner ring 32a, an outer ring 33a, and a rolling element 34a arranged between the inner ring 32a and the outer ring 33a. The third bearing 31c has an inner ring 32c, an outer ring 33c, and a rolling element 34c arranged between the inner ring 32c and the outer ring 33c.

[0078] 6 and 10, the second bearing 36b constitutes at least a part of the rear bearing 36 that supports the rear end portion 22 of the rotating body 2. The second bearing 36b is, for example, a roller bearing.

[0079] (Recovery device 7) In the example shown in FIG. 10 , the recovery device 7 includes: (1) a plurality of recovery flow paths including a first recovery flow path 71, a second recovery flow path 72, and a third recovery flow path 73; (2) a plurality of pipelines including a first pipeline 74 a, a second pipeline 74 b, and a third pipeline 74 c; (3) a plurality of ejectors including a first ejector 75 a, a second ejector 75 b, and a third ejector 75 c; and (4) a plurality of flow control valves including a first flow control valve 76 a, a second flow control valve 76 b, and a third flow control valve 76 c.

[0080] The first recovery flow path 71, the second recovery flow path 72, the first pipe line 74a, the second pipe line 74b, the first ejector 75a, the second ejector 75b, the first flow control valve 76a, and the second flow control valve 76b have already been described in the first embodiment, so repeated explanations of these configurations will be omitted.

[0081] The third recovery passage 73 is provided in the housing 4. In the example shown in Figure 11, all or most of the third recovery passage 73 is disposed inside the housing 4. All or most of the third recovery passage 73 may be constituted by a through-hole formed in the housing 4.

[0082] The third recovery passage 73 recovers oil-containing fluid that contains oil that has passed through the first bearing 31a without being recovered by the first recovery passage 71. Hereinafter, the oil-containing fluid recovered via the third recovery passage 73 will be referred to as the "third oil-containing fluid." In the example shown in Figure 10, the third recovery passage 73 is a passage separate from the first recovery passage 71 and the second recovery passage 72.

[0083] 10 , the third conduit 74c fluidly connects the third recovery passage 73 and a third ejector 75c disposed outside the housing 4. In the example shown in FIG. 10 , the entire third conduit 74c is disposed outside the housing 4. Alternatively, a portion of the third conduit 74c may be disposed inside the housing 4, and a majority of the third conduit 74c may be disposed outside the housing 4.

[0084] The third ejector 75c generates negative pressure using air supplied from the third air flow path 77c, thereby sucking the third oil-containing fluid from the third recovery flow path 73. Hereinafter, the air supplied to the third ejector 75c from the third air flow path 77c will be referred to as "third air." In the example shown in FIG. 10, the third ejector 75c generates negative pressure in the third pipe line 74c using the third air supplied from the third air flow path 77c, and sucks the third oil-containing fluid from the third recovery flow path 73 via the third pipe line 74c. In the example shown in FIG. 10, the third ejector 75c is an ejector that is one-to-one associated with the third recovery flow path 73 via the third pipe line 74c.

[0085] The third flow control valve 76c adjusts the flow rate of the third air supplied from the third air flow path 77c to the third ejector 75c. The opening degree of the third flow control valve 76c may be set manually or by the controller 8.

[0086] 11 , the spindle lubrication device 1 of the machine tool has a third recovery passage 73 that recovers a third oil-containing fluid that includes oil that has passed through the first bearing 31 a without being recovered by the first recovery passage 71. Therefore, the oil that has passed through the first bearing 31 a is effectively prevented from leaking from the gap between the rotating body 2 and the tip end 46 of the housing 4.

[0087] For example, consider a case where it is undesirable for oil to adhere to a workpiece being machined by the tool T. More specifically, consider a case where a workpiece made of a carbon material, to which adhesion of oil would cause problems, is machined. In such a case, the embodiment including the third recovery flow path 73 is useful.

[0088] Furthermore, dry machining may be used when processing resin materials or the like using the tool T. In the embodiment including the third recovery flow path 73, oil leakage from the gap between the rotating body 2 and the tip end 46 of the housing 4 is suppressed, and oil adhesion to the workpiece (e.g., resin material, etc.) is effectively suppressed. Therefore, the embodiment including the third recovery flow path 73 is useful even when dry machining is used.

[0089] In the embodiment including the third recovery passage 73, oil is prevented from leaking from the gap between the rotor 2 and the tip 46 of the housing 4. Therefore, when coolant is used during machining of the workpiece (in other words, when dry machining is not performed), oil is prevented from mixing with the coolant, thereby reducing the burden on the environment.

[0090] 10, the recovery device 7 includes an exhaust pipeline 78, an exhaust cleaner 791, and a recovery container 792. In the example shown in Fig. 10, the exhaust pipeline 78 fluidly connects the first ejector 75a, the second ejector 75b, and the third ejector 75c to the exhaust cleaner 791.

[0091] The exhaust cleaner 791 receives the oil-containing fluid from the plurality of ejectors (75a, 75b, 75c) via the exhaust pipe 78. The exhaust cleaner 791 also separates the oil-containing fluid received from the exhaust pipe 78 into liquid oil and air. The liquid oil separated from the oil-containing fluid by the exhaust cleaner 791 is collected in a collection container 792.

[0092] (Structure of Ejector 75) Figure 12 shows an example of the structure of the ejector 75. The ejector 75 has an inlet port 751, an outlet port 752, and a vacuum port 753. When compressed air is supplied to the inlet port 751 of the ejector 75, the fluid to be sucked is sucked into the ejector 75 via the vacuum port 753 of the ejector 75. The compressed air and the fluid to be sucked are discharged from the ejector 75 via the outlet port 752. When the flow rate of the compressed air supplied to the inlet port 751 increases, the flow rate of the fluid to be sucked into the ejector 75 increases. On the other hand, when the flow rate of the compressed air supplied to the inlet port 751 decreases, the flow rate of the fluid to be sucked into the ejector 75 decreases.

[0093] With regard to the first ejector 75a, the first air flow path 77a is connected to the inlet port 751a, the exhaust pipe 78 is connected to the outlet port 752a, and the first pipe 74a is connected to the vacuum port 753a. With regard to the second ejector 75b, the second air flow path 77b is connected to the inlet port 751b, the exhaust pipe 78 is connected to the outlet port 752b, and the second pipe 74b is connected to the vacuum port 753b. With regard to the third ejector 75c, the third air flow path 77c is connected to the inlet port 751c, the exhaust pipe 78 is connected to the outlet port 752c, and the third pipe 74c is connected to the vacuum port 753c.

[0094] 13 , the spindle lubrication device 1 of a machine tool may include an air supply device 9. The air supply device 9 has an air source AS (e.g., an air compressor) arranged outside the housing 4, an air supply flow path 93 provided in the housing 4, an air supply pipe 91 connecting the air source AS and the air supply flow path 93, and a fourth flow control valve 96.

[0095] 13 , the air supply pipe 91 is disposed outside the housing 4. The air supply pipe 91 supplies air to an air supply flow path 93. Hereinafter, the air supplied from the air supply pipe 91 to the air supply flow path 93 will be referred to as "fourth air." The fourth flow control valve 96 adjusts the flow rate of the fourth air supplied from the air supply pipe 91 to the air supply flow path 93. In the example shown in FIG. 13 , the fourth flow control valve 96 is disposed in the air supply pipe 91. The opening degree of the fourth flow control valve 96 may be set manually or by the controller 8.

[0096] 14 , an air ejection port OP1 is formed between the rotating body 2 (more specifically, the rotating shaft 20) and the tip end 46 of the housing 4. The housing 4 also has a discharge port 49 formed therein that discharges the fourth air received from the air supply passage 93 into the gap G between the rotating body 2 and the housing 4. The fourth air discharged from the discharge port 49 forms both a first flow that flows from the gap G toward the third recovery passage 73, and a second flow that flows from the gap G toward the air ejection port OP1.

[0097] The fourth air injected from the air injection port OP1 prevents foreign matter such as chips from entering the housing 4 through the gap G. More specifically, in the example shown in FIG. 13 , the fourth air injected from the air injection port OP1 forms an air curtain AC around the tool T or the tool holder HD. The air curtain AC prevents foreign matter such as chips from entering the housing 4 through the gap G.

[0098] 14 , the first flow from the gap G toward the third recovery passage 73 (more specifically, the fourth air flow from the gap G toward the third recovery passage 73) pushes the oil E1 that has entered the gap G back toward the third recovery passage 73. This further effectively prevents oil from leaking from the gap between the rotating body 2 and the tip end 46 of the housing 4.

[0099] The third recovery passage 73 contains a relatively large amount of fourth air (i.e., fourth air discharged from the discharge port 49) compared to the other recovery passages (71, 72). In the example shown in FIG. 13 , the third conduit 74c contains a relatively large amount of fourth air (i.e., fourth air discharged from the discharge port 49) compared to the other conduits (74a, 74b). In such a case, if equal suction forces are applied to the first conduit 74a, the second conduit 74b, and the third conduit 74c, an imbalance in oil recovery is likely to occur among the multiple bearings. In contrast, in the example shown in FIG. 13 , the suction forces applied to the first conduit 74a, the second conduit 74b, and the third conduit 74c can be independently adjusted. Therefore, by individually and appropriately setting these suction forces, poor lubrication can be prevented in each of the multiple bearings.

[0100] (Setting the Opening Degree of the First Flow Control Valve 76a and the Opening Degree of the Second Flow Control Valve 76b) In each of Figures 15 and 16, it is assumed that the mixed fluid is supplied at a first flow rate from the mixed fluid supply device 6 to the plurality of bearings 3 (see arrow AR1). In each of Figures 15 and 16, it is assumed that the fourth air is supplied at a second flow rate to the air supply passage 93 (see arrow AR7). Also, in each of Figures 15 and 16, it is assumed that air is being injected from the air injection port OP1 (see arrow AR6).

[0101] 15 shows a state in which multiple conduits (74a, 74b, 74c) are fluidly connected to multiple recovery flow paths (71, 72, 73), respectively. More specifically, in the example shown in FIG. 15, first conduit 74a is fluidly connected to first recovery flow path 71, second conduit 74b is fluidly connected to second recovery flow path 72, and third conduit 74c is fluidly connected to third recovery flow path 73.

[0102] 16 illustrates a state in which multiple conduits (74a, 74b, 74c) are fluidly isolated from multiple recovery channels (71, 72, 73). More specifically, in the example illustrated in FIG. 16, first conduit 74a is fluidly isolated from first recovery channel 71, second conduit 74b is fluidly isolated from second recovery channel 72, and third conduit 74c is fluidly isolated from third recovery channel 73.

[0103] As illustrated in Figure 15, a plurality of pipes (74a, 74b, 74c) are fluidly connected to a plurality of recovery flow paths (71, 72, 73), a first flow rate of the mixed fluid is supplied from the mixed fluid supply device 6 to a plurality of bearings 3, and a second flow rate of fourth air is supplied to the air supply flow path 93. Under this third condition CD3, the flow rate of the first oil-containing fluid flowing through the first pipe 74a is defined as the first recovery flow rate (see arrow AR2 in Figure 15). Furthermore, under the above-mentioned third condition CD3, the flow rate of the second oil-containing fluid flowing through the second pipe 74b is defined as the second recovery flow rate (see arrow AR3 in Figure 15). Note that since the methods for measuring the first recovery flow rate and the second recovery flow rate have already been described, repeated explanations of these measurement methods will be omitted.

[0104] As illustrated in Figure 16, under a fourth condition CD4 which differs from the above-mentioned third condition CD3 only in that the multiple pipes (74a, 74b, 74c) are fluidically separated from the multiple recovery flow paths (71, 72, 73), the flow rate of the first oil-containing fluid discharged from the first recovery flow path 71 to the outside of the first recovery flow path 71 (e.g., outside the housing 4) is defined as a first discharge flow rate (see arrow AR4 in Figure 16). Furthermore, under the above-mentioned fourth condition CD4, the flow rate of the second oil-containing fluid discharged from the second recovery flow path 72 to the outside of the second recovery flow path 72 (e.g., outside the housing 4) is defined as a second discharge flow rate (see arrow AR5 in Figure 16). Note that since the measurement methods (or derivation methods) of the first recovery flow rate and the second recovery flow rate have already been explained, repeated explanations of these measurement methods (or derivation methods) will be omitted.

[0105] The third condition CD3 described above may include a condition that the rotation angle of the rotating body 2 about the first axis AX1 relative to the housing 4 is maintained. In this case, the fourth condition CD4 described above includes a condition that the rotation angle of the rotating body 2 about the first axis AX1 relative to the housing 4 is maintained. Alternatively, the third condition CD3 described above may include a condition that the rotating body 2 rotates about the first axis AX1 relative to the housing 4 at a predetermined rotation speed (e.g., 20,000 rpm, or the maximum rotation speed in the design specifications of the spindle lubrication device, etc.). In this case, the fourth condition CD4 described above includes a condition that the rotating body 2 rotates about the first axis AX1 relative to the housing 4 at the predetermined rotation speed (e.g., 20,000 rpm, or the maximum rotation speed in the design specifications of the spindle lubrication device, etc.).

[0106] In the above-described third condition CD3, the flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 (i.e., the first flow rate) is equal to the flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 (i.e., the first flow rate) in the above-described fourth condition CD4. Assume that an upper limit value and a lower limit value of the flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 during operation of the main shaft lubrication device 1 are predetermined. In this case, in each of the above-described third condition CD3 and the above-described fourth condition CD4, the value of the first flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 is set to any value within a range not less than the above-described lower limit value and not more than the above-described upper limit value. In each of the above-described third condition CD3 and the above-described fourth condition CD4, the value of the first flow rate of the mixed fluid supplied from the mixed fluid supply device 6 to the plurality of bearings 3 may be set to the above-described upper limit value, may be set to the above-described lower limit value, or may be set to a value smaller than the above-described upper limit value and larger than the above-described lower limit value.

[0107] The flow rate of the fourth air supplied to the air supply flow path 93 under the third condition CD3 (i.e., the second flow rate) is equal to the flow rate of the fourth air supplied to the air supply flow path 93 under the fourth condition CD4 (i.e., the second flow rate). Under the fourth condition CD4, the flow rate of the air injected from the air injection port OP1 is defined as the "third flow rate." Under the fourth condition CD4 (see FIG. 16 ), it is preferable to set the flow rate of the fourth air supplied to the air supply flow path 93 (i.e., the second flow rate) so that the third flow rate is equal to the flow rate required to form an air curtain (e.g., the design lower limit flow rate for forming an air curtain).

[0108] 17 , the aperture of the first flow control valve 76a is set so that the first recovery flow rate is within a range of 1 to 1.5 times the first discharge flow rate (more preferably, so that the first recovery flow rate is within a range of 1 to 1.2 times the first discharge flow rate). The aperture of the first flow control valve 76a may be set manually or by the controller 8. The aperture of the second flow control valve 76b is set so that the second recovery flow rate is within a range of 1 to 1.5 times the second discharge flow rate (more preferably, so that the second recovery flow rate is within a range of 1 to 1.2 times the second discharge flow rate). The aperture of the second flow control valve 76b may be set manually or by the controller 8.

[0109] The above-mentioned third condition CD3 is one aspect of the above-mentioned first condition CD1, and the above-mentioned fourth condition CD4 is one aspect of the above-mentioned second condition CD2.

[0110] (Setting the Opening Degree of the Third Flow Control Valve 76c and the Opening Degree of the Fourth Flow Control Valve 96) Figure 17 shows a state after the opening degrees of the first flow control valve 76a and the second flow control valve 76b have been set. In the example shown in Figure 17, the opening degrees of the third flow control valve 76c and the opening degrees of the fourth flow control valve 96 are set so that the flow rate of the fourth air discharged from the discharge port 49 (see Figure 14) is greater than the flow rate of air injected from the air injection port OP1 (see Figure 14). In the example shown in Figure 14, by setting the flow rate of the fourth air discharged from the discharge port 49 to be greater than the flow rate of air injected from the air injection port OP1, the injection of oil E1 from the air injection port OP1 in conjunction with the injection of air from the air injection port OP1 is prevented or suppressed.

[0111] 14 , oil E1 may be directed toward the air ejection port OP1 from the gap between the housing 4 and the rotating body 2. More specifically, if the flow rate of air ejected from the air ejection port OP1 becomes larger than the flow rate of the fourth air ejected from the outlet 49, oil E1 may be ejected from the air ejection port OP1 in conjunction with the ejection of air from the air ejection port OP1. Therefore, it is preferable to appropriately set the relationship between the opening degree of the third flow control valve 76c and the opening degree of the fourth flow control valve 96 so that the flow rate of air ejected from the air ejection port OP1 does not become larger than the flow rate of the fourth air ejected from the outlet 49.

[0112] 17, the aperture of the third flow control valve 76c and the aperture of the fourth flow control valve 96 are preferably set so that the flow rate of air injected from the air injection port OP1 is equal to or greater than the third flow rate (more specifically, equal to or greater than the design lower limit flow rate for forming an air curtain). This setting favorably forms an air curtain that prevents foreign matter from entering the machining head 10 from the tip end of the machining head 10.

[0113] In the example shown in FIG. 17 , a portion of the fourth air discharged from the discharge port 49 is recovered via the third recovery passage 73, which can reduce the flow rate of air sprayed from the air jet port OP1. Therefore, in the example shown in FIG. 17 , by sufficiently increasing the aperture of the fourth flow control valve 96, the flow rate of air sprayed from the air jet port OP1 can be set to the third flow rate or higher while a portion of the fourth air discharged from the discharge port 49 is recovered via the third recovery passage 73. By recovering a portion of the fourth air discharged from the discharge port 49 via the third recovery passage 73, oil E1 (see FIG. 14 if necessary) is prevented from flowing toward the air jet port OP1. Furthermore, by spraying air at a flow rate equal to or higher than the third flow rate from the air jet port OP1, foreign matter is prevented from entering the machining head 10 from the tip of the machining head 10.

[0114] 17 , the aperture of the third flow control valve 76c and the aperture of the fourth flow control valve 96 may be set so that the flow rate of air injected from the air injection port OP1 is 1 to 1.5 times the third flow rate (more specifically, the design lower limit flow rate for forming an air curtain). By setting the flow rate of air injected from the air injection port OP1 to 1.5 times the third flow rate, the amount of air injected from the air injection port OP1 will not be excessive.

[0115] (Mixed fluid supply device 6) In the example shown in FIG. 17 , the mixed fluid supply device 6 has an air source AT (e.g., an air compressor), an oil tank 61, a pump 62, a second air supply pipe 63, a mixer 64, a supply flow path 66, and a mixed fluid supply pipe 68 connecting the mixer 64 and the supply flow path 66.

[0116] The air source AT supplies air to the mixer 64 via the second air supply pipe 63. Hereinafter, the air supplied to the mixer 64 via the second air supply pipe 63 will be referred to as "fifth air." The pump 62 supplies oil from the oil tank 61 to the mixer 64. The mixer 64 mixes the fifth air received from the air source AT via the second air supply pipe 63 with the oil received from the oil tank 61 to form a mixed fluid containing oil and air. The mixer 64 also sends the mixed fluid to the supply flow path 66 via a mixed fluid supply pipe 68.

[0117] 17 , the mixed fluid supply pipe 68 is disposed outside the housing 4, and the supply flow path 66 is disposed inside the housing 4. The supply flow path 66 supplies a mixed fluid containing oil and air (more specifically, oil-air) to the plurality of bearings 3. In the example shown in FIG. 17 , the supply flow path 66 supplies the mixed fluid containing oil and air to the first bearing 31 a, the second bearing 36 b, and the third bearing 31 c.

[0118] 17 , the air source AT that supplies air to the mixer 64 and the air source AS that supplies air to the multiple ejectors (75 a, 75 b, 75 c) are the same. By sharing the air source AT that supplies air to the mixer 64 and the air source AS that supplies air to the multiple ejectors (75 a, 75 b, 75 c), space can be saved. Furthermore, manufacturing costs and energy consumption can be reduced. Alternatively, the air source AT that supplies air to the mixer 64 may be a different air source from the air source AS that supplies air to the multiple ejectors (75 a, 75 b, 75 c).

[0119] The mixed fluid supply device 6 may have a fifth flow control valve 67 that adjusts the flow rate of air supplied from the second air supply pipe 63 to the mixer 64. In the example shown in Fig. 17 , the fifth flow control valve 67 is disposed in the second air supply pipe 63. The opening of the fifth flow control valve 67 may be set manually or by the controller 8.

[0120] (First air flow path 77a, second air flow path 77b, and third air flow path 77c) The first air flow path 77a and the second air flow path 77b have already been described in the first embodiment, so repeated description of these flow paths will be omitted. In the example shown in Figure 17, the recovery device 7 has a third air flow path 77c that supplies third air to the third ejector 75c. In the example shown in Figure 17, a third flow control valve 76c is arranged in the third air flow path 77c.

[0121] 17, the machine tool spindle lubrication device 1 has a main air flow path 12 that connects the first air flow path 77a, the second air flow path 77b, and the third air flow path 77c to the air source AS. In the example shown in Fig. 17, the main air flow path 12 is branched into a plurality of air flow paths including the first air flow path 77a, the second air flow path 77b, and the third air flow path 77c.

[0122] The main air flow path 12 may be connected to an air supply pipe 91 that supplies air to an air supply flow path 93 provided in the housing 4. The main air flow path 12 may also be connected to a second air supply pipe 63 that supplies fifth air to the mixer 64.

[0123] (On-off valve 13) In the example shown in FIG. 18, the spindle lubrication device 1 of the machine tool has a plurality of on-off valves 13 arranged between the air source AS and a plurality of flow control valves (76a, 76b, 76c, 67, 96).

[0124] 18, the recovery device 7 has a first on-off valve 13a and a second on-off valve 13b. Additionally, the recovery device 7 may have a third on-off valve 13c.

[0125] The first on-off valve 13a is disposed between the air source AS and the first flow control valve 76a. More specifically, the first on-off valve 13a is disposed in the first air flow path 77a. The first on-off valve 13a opens and closes the first air flow path 77a between the air source AS and the first flow control valve 76a.

[0126] The second on-off valve 13b is disposed between the air source AS and the second flow control valve 76b. More specifically, the second on-off valve 13b is disposed in the second air flow path 77b. The second on-off valve 13b opens and closes the second air flow path 77b between the air source AS and the second flow control valve 76b.

[0127] The third on-off valve 13c is disposed between the air source AS and the third flow control valve 76c. More specifically, the third on-off valve 13c is disposed in the third air flow path 77c. The third on-off valve 13c opens and closes the third air flow path 77c between the air source AS and the third flow control valve 76c.

[0128] 18 , the air supply device 9 has a fourth on-off valve 13d. The fourth on-off valve 13d is disposed between the air source AS and the fourth flow rate control valve 96. More specifically, the fourth on-off valve 13d is disposed in the air supply pipe 91. The fourth on-off valve 13d opens and closes the flow path of the air supply pipe 91 between the air source AS and the fourth flow rate control valve 96.

[0129] 18 , the mixed fluid supply device 6 has a fifth on-off valve 13e. The fifth on-off valve 13e is disposed between the air source AS and the fifth flow rate control valve 67. More specifically, the fifth on-off valve 13e is disposed in the second air supply pipe 63. The fifth on-off valve 13e opens and closes the flow path of the second air supply pipe 63 between the air source AS and the fifth flow rate control valve 67.

[0130] (Controller 8) The controller 8 controls the mixed fluid supply device 6 and the recovery device 7. Additionally, the controller 8 may control the air supply device 9.

[0131] 18 , the controller 8 includes a processor 80, a memory 82 that stores programs and data, and a communication circuit 84. In the example shown in Fig. 18 , the processor 80, the memory 82, and the communication circuit 84 are connected via a bus 88.

[0132] The controller 8 may be configured as a microcontroller in which the processor 80, memory 82, and communication circuit 84 are integrated into a single integrated circuit, or may be configured as a computer in which a CPU as the processor 80, a storage unit as the memory 82, and a communication unit as the communication circuit 84 are separately provided.

[0133] The controller 8 controls the air source AS. The controller 8 drives the air source AS (for example, an air compressor) by sending a drive command C to the air source AS.

[0134] The controller 8 controls the mixed fluid supply device 6. More specifically, the controller 8 transmits a first group of control commands C1 to the mixed fluid supply device 6, and the mixed fluid supply device 6, which receives the first group of control commands C1, supplies the mixed fluid at a first flow rate to the plurality of bearings 3. For example, the controller 8 transmits the first group of control commands C1 to the fifth on-off valve 13e and the pump 62, thereby supplying the mixed fluid containing oil and air to the plurality of bearings 3 using the mixed fluid supply device 6.

[0135] The controller 8 controls the recovery device 7. The controller 8 transmits a second group of control commands C2 to the recovery device 7, and the recovery device 7, upon receiving the second group of control commands C2, recovers the oil-containing fluid. For example, the controller 8 transmits the second group of control commands C2 to the first on-off valve 13a, the second on-off valve 13b, and the third on-off valve 13c, thereby recovering the oil-containing fluid using the recovery device 7. When the opening degree of the first flow control valve 76a is set to the first opening degree, poor lubrication of the bearings does not occur due to the suction force of the first ejector 75a. When the opening degree of the second flow control valve 76b is set to the second opening degree, poor lubrication of the bearings does not occur due to the suction force of the second ejector 75b.

[0136] The controller 8 may control the air supply device 9 so that air is ejected from the air ejection port OP1. The controller 8 transmits a third group control command C3 to the air supply device 9, and the air supply device 9, upon receiving the third group control command C3, supplies fourth air to the discharge port 49 formed in the housing 4. For example, the controller 8 transmits the control command C3 to the fourth on-off valve 13 d, thereby causing the air supply device 9 to supply the fourth air to the discharge port 49. A portion of the fourth air supplied to the discharge port 49 is ejected from the air ejection port OP1, and a portion of the fourth air supplied to the discharge port 49 is recovered by the recovery device 7 via the third recovery passage 73.

[0137] By appropriately setting the opening degree of the third flow control valve 76c and the opening degree of the fourth flow control valve 96, (1) the third oil-containing fluid containing oil that has passed through the first bearing 31a without being recovered by the first recovery passage 71 is recovered via the third recovery passage 73, (2) oil is prevented or suppressed from mixing with the air sprayed from the air injection port OP1, and (3) an air curtain is suitably formed by the air sprayed from the air injection port OP1.

[0138] (First rotation drive device 5) In the example shown in Fig. 17 , the spindle lubrication device 1 of a machine tool includes a first rotation drive device 5 that rotates the rotating body 2 (more specifically, the rotating shaft 20) about the first axis AX1. The first rotation drive device 5 may be a first motor. In the example shown in Fig. 17 , the first rotation drive device 5 (more specifically, the first motor) has a stator 51 and a rotor 53. In this case, when a current is supplied to the stator 51, the rotor 53 rotates about the first axis AX1 due to electromagnetic action. In the example shown in Fig. 17 , the stator 51 is fixed to the housing 4, and the rotor 53 is fixed to the rotating body 2 (more specifically, the rotating shaft 20).

[0139] 17, the rotor 53 is disposed in the intermediate portion 23 of the rotating shaft 20. The rotor 53 is disposed closer to the second direction DR2 than the first bearing 31a and closer to the first direction DR1 than the second bearing 36b.

[0140] 17 , the first rotation drive device 5 is disposed inside the housing 4. Alternatively, the first rotation drive device 5 may be disposed outside the housing 4. For example, the first rotation drive device 5 disposed outside the housing 4 may be configured to rotate the rotating body 2 via any power transmission mechanism (e.g., gears, transmission belts, etc.).

[0141] (Machining head 10) The spindle lubrication device 1 of the machine tool includes a machining head 10. In the example shown in Fig. 19 , the machining head 10 has (1) a rotating body 2 that holds a tool T, (2) a plurality of bearings 3 including a first bearing 31a and a second bearing 36b, (3) a housing 4 that rotatably supports the rotating body 2 about a first axis AX1 via the plurality of bearings 3, and (4) a first rotation drive device 5 that rotates the rotating body 2 about the first axis AX1.

[0142] (Rotating Body 2) In the example shown in FIG. 19 , the rotating body 2 has a rear end portion 22 and a front end portion 24 that holds the tool T. More specifically, the rotating body 2 (more specifically, the rotating shaft 20) has a rotating shaft main body 21, an attachment portion 28 to which the tool T is attached, and a rod-shaped member 291 connected to the attachment portion 28. The rod-shaped member 291 is disposed inside the rotating shaft main body 21. In the example shown in FIG. 19 , when the attachment portion driving device 14 of the machining head 10 presses the rod-shaped member 291 in the first direction DR1, the rod-shaped member 291 and the attachment portion 28 move relative to the rotating shaft main body 21 in the first direction DR1. In this state, the tool T attached to the attachment portion 28 can be replaced with another tool. After the tool is replaced, a biasing member 293 (e.g., a disc spring) disposed on the rotating shaft 20 presses the rod-shaped member 291 in the second direction DR2. In this way, the rod-shaped member 291 and the attachment portion 28 move relative to the rotary shaft main body 21 in the second direction DR2.

[0143] 20, the rotating body 2 (more specifically, the rotating shaft main body 21) has an inner circumferential surface 21n that contacts the tool holder HD. The inner circumferential surface 21n is, for example, a tapered surface whose diameter increases in the first direction DR1.

[0144] In the example shown in FIG. 21, the rotating body 2 (more specifically, the rotating shaft 20) has a first portion 25, a second portion 26, and a step surface 25a.

[0145] The first portion 25 supports the inner ring 32a of the first bearing 31a. The first portion 25 has a first outer circumferential surface 25u.

[0146] The second portion 26 has a second outer peripheral surface 26u that has a smaller diameter than the first outer peripheral surface 25u. In other words, the diameter of the second outer peripheral surface 26u of the second portion 26 is smaller than the diameter of the first outer peripheral surface 25u of the first portion 25. The second portion 26 is disposed closer to the first direction DR1 than the first portion 25.

[0147] The step surface 25 a connects the first outer peripheral surface 25 u of the first portion 25 and the second outer peripheral surface 26 u of the second portion 26 .

[0148] 21 , each of the first portion 25 of the rotating body 2 and the second portion 26 of the rotating body 2 is formed by a part of the rotating shaft main body 21. Alternatively, at least a part of the first portion 25 of the rotating body 2 and the second portion 26 of the rotating body 2 may be formed by a member other than the rotating shaft main body 21 (for example, an inner ring holder that is separate from the rotating shaft main body 21).

[0149] (Housing 4) In the example shown in FIG. 19, the housing 4 has a front end portion 4a, a rear end portion 4b, and an intermediate portion 4c between the front end portion 4a and the rear end portion 4b.

[0150] As illustrated in Fig. 20, the tip portion 4a of the housing 4 supports the outer ring of the front bearing 31. In the example illustrated in Fig. 20, the tip portion 4a of the housing 4 supports the outer ring 33a of the first bearing 31a and the outer ring 33c of the third bearing 31c.

[0151] The housing 4 may include a flange 47 that protrudes outward. In the example shown in FIG. 20 , the flange 47 is disposed on the tip portion 4a of the housing 4. The flange 47 may be provided with an outlet port 71p of the first recovery passage 71. In the example shown in FIG. 20 , the above-described first pipe 74a is connected to the outlet port 71p. The flange 47 may be provided with an outlet port 73p of the third recovery passage 73. In the example shown in FIG. 20 , the above-described third pipe 74c is connected to the outlet port 73p. The flange 47 may be provided with an inlet port 93p of the air supply passage 93. In the example shown in FIG. 20 , the above-described air supply pipe 91 is connected to the inlet port 93p. In the example shown in FIG. 20 , a supply passage 66 is provided in the housing 4. In the example shown in FIG. 20 , the supply passage 66 supplies a mixed fluid containing oil and air (more specifically, oil-air) to the front bearings including the first bearing 31a and the third bearing 31c.

[0152] The rear end portion 4b of the housing 4 supports the outer ring of the rear bearing 36. In the example shown in Fig. 19, the rear end portion 4b of the housing 4 supports the outer ring 37b of the second bearing 36b. The rear end portion 4b may have an end plate 40b arranged at the end of the housing 4 on the second direction DR2 side.

[0153] 19, the intermediate portion 4c of the housing 4 has a cylindrical side wall 40c. The intermediate portion 4c of the housing 4 (more specifically, the cylindrical side wall 40c) may support the stator 51 described above.

[0154] In the example shown in FIG. 21 , the housing 4 (more specifically, the tip portion 4 a of the housing 4 ) has a third portion 41 and a fourth portion 42 .

[0155] The third portion 41 supports the outer ring 33a of the first bearing 31a. As illustrated in FIG. 22 , a first gap G1 is formed between the first portion 25 of the rotating body 2 and the third portion 41 of the housing. In the example illustrated in FIG. 22 , oil E that has passed through the first bearing 31a is present in the first gap G1. In the first gap G1, the oil E may be present in the form of oil-air, oil mist, or liquid oil. In the example illustrated in FIG. 22 , the first gap G1 is linear in a vertical cross section including the first axis AX1. Alternatively, the first gap G1 may have a labyrinth shape in a vertical cross section including the first axis AX1. Alternatively, or additionally, as illustrated in FIG. 23 , a notch CT may be formed in a portion of a surface defining the first gap G1. The notch CT may be formed on the first outer peripheral surface 25 u of the rotating body 2 or on the surface of the third portion 41 of the housing 4 .

[0156] The fourth portion 42 defines an annular receiving space SP that receives the oil E from the first gap G1. Within the annular receiving space SP, the oil E may exist in the form of oil-air, oil mist, or liquid oil. There are no limitations on the shape of the annular receiving space SP, and the shape of the annular receiving space SP may be any shape.

[0157] 23, the first gap G1 and the annular receiving space SP are arranged on a straight line LN parallel to the first axis AX1. In this case, the oil E present in the first gap G1 is smoothly guided into the annular receiving space SP.

[0158] In the example shown in FIG. 23 , the fourth portion 42 has an opening 45 that guides the oil E from the annular receiving space SP to the third recovery passage 73 .

[0159] 24 , a second gap G2 fluidly communicating with the first gap G1 is formed between the housing 4 and the step surface 25 a of the rotor 2. In addition, a third gap G3 fluidly communicating with the second gap G2 is formed between the housing 4 and the second outer circumferential surface 26 u of the rotor 2.

[0160] A path from the first gap G1 to the outside of the machining head 10 is assumed. This path can be a source of oil leakage. In the example shown in FIG. 24 , the path from the first gap G1 to the outside of the machining head 10 includes a second gap G2 between the housing 4 and the step surface 25a. Therefore, the presence of the second gap G2 prevents oil from leaking outside the machining head 10 via the above-mentioned path.

[0161] 24 , the first gap G1 and the second gap G2 extend in different directions. This prevents oil in the first gap G1 from moving toward the second gap G2. For example, oil moving downward from the first gap G1 is prevented from entering the second gap G2. In the example shown in FIG. 24 , the first gap G1 extends in the first direction DR1, and the second gap G2 extends in the radially inward direction DR3 (more specifically, a direction perpendicular to the first axis AX1 and toward the first axis AX1).

[0162] 24, the third gap G3 is connected to the second gap G2 via a corner CN. The extending direction of the third gap G3 is different from the extending direction of the second gap G2. In the example shown in FIG. 24, the extending direction of the third gap G3 is the first direction DR1, and the extending direction of the second gap G2 is the radially inward direction DR3 (more specifically, the direction perpendicular to the first axis AX1 and toward the first axis AX1).

[0163] 25 , the fourth portion 42 has a base 43 connected to the third portion 41, and an annular protrusion 44 protruding in a direction toward the first axis AX1 from the base 43. Note that in FIG. 25 , the annular protrusion 44 is hatched with dots to make it easier to understand the shape of the annular protrusion 44.

[0164] As illustrated in Figure 24, the annular protrusion 44 has a first surface 44a facing the step surface 25a and a second surface 44b facing the outer peripheral surface of the second part 26 of the rotating body 2 (in other words, the second outer peripheral surface 26u).

[0165] Additionally, the annular protrusion 44 may have an annular protrusion 441 that protrudes in a direction away from the first axis AX1. The annular protrusion 441 faces both the stepped surface 25a and the annular receiving space SP. When the fourth portion 42 (more specifically, the annular protrusion 44 of the fourth portion 42) has the annular protrusion 441 that protrudes in a direction away from the first axis AX1, the oil E that has entered the annular receiving space SP is less likely to flow back toward the second gap G2. This effectively prevents oil from leaking out of the machining head 10 from the gap between the rotating body 2 and the tip end 46 of the housing 4.

[0166] 25 , the housing 4 has a first part CP1 (more specifically, the annular first part CP1) including the above-described annular protrusion 441, and a second part CP2 (more specifically, the annular second part CP2) that supports the first part CP1. When the first part CP1 including the annular protrusion 441 is a part different from the second part CP2, the degree of freedom in designing the internal shape of the housing 4 (for example, the degree of freedom in the shape of the annular receiving space SP) increases.

[0167] 25 , the first part CP1 and the second part CP2 each have a portion facing the annular receiving space SP. In a vertical cross section passing through the first axis AX1, the first part CP1 may have a substantially L-shape or another shape. The second part CP2 may be an end plate disposed at the end of the housing 4 on the first direction DR1 side.

[0168] In the example shown in Figure 24, the annular protrusion 44 has a first wall 440a that defines the bottom surface of the annular receiving space SP (in other words, the end surface on the first direction DR1 side of the annular receiving space SP), and a second wall 440b that defines a second surface 44b facing the second outer peripheral surface 26u of the rotating body 2.

[0169] 24 , the first wall 440a is an annular wall that is continuous with the base 43 of the fourth portion 42 and extends from the base 43 in the radially inward direction DR3. The second wall 440b is an annular wall that is continuous with the inner edge of the first wall 440a and extends from the inner edge in the second direction DR2. The annular protrusion 441 is continuous with the end of the second wall 440b on the second direction DR2 side and protrudes from that end in the radially outward direction DR4.

[0170] The annular protrusion 44 may have a first annular groove V1. In the example shown in Fig. 24, the first annular groove V1 is a groove facing the annular receiving space SP and recessed in the radially inward direction DR3. The first annular groove V1 prevents or suppresses oil in the annular receiving space SP from flowing back toward the second gap G2.

[0171] 24 , the fourth portion 42 of the housing 4 has a second annular groove V2. The second annular groove V2 faces the annular receiving space SP and is recessed in the radially outward direction DR4 (in other words, the direction away from the first axis AX1). In the example shown in FIG. 24 , the second annular groove V2 is disposed in the fourth portion 42 of the housing 4 so as to face the first annular groove V1.

[0172] 26 , to make it easier to understand the shapes of the first annular groove V1 and the second annular groove V2, portions other than the first annular groove V1 and the second annular groove V2 are indicated by dashed lines, and the first annular groove V1 and the second annular groove V2 are indicated by solid lines. In the example shown in FIG. 26 , both the first annular groove V1 and the second annular groove V2 can hold oil. In this case, the annular receiving space SP includes a space defined by the first annular groove V1 and a space defined by the second annular groove V2, which allows the overall volume of the annular receiving space SP to be increased.

[0173] 26 , the annular protrusion 44 has a third surface 44 f that constitutes a part of the end surface 4 f on the first direction DR1 side of the housing 4. The third surface 44 f is the surface on the first direction DR1 side of the first wall 440 a described above.

[0174] (Air injection port OP1 and discharge port 49) In the example shown in FIG. 24, an air injection port OP1 communicating with the third gap G3 is formed between the tip end 46 of the housing 4 and the rotating body 2.

[0175] The housing 4 is also formed with an air supply flow path 93 through which the fourth air supplied from the air supply pipe 91 flows, and an outlet 49 that discharges the fourth air. The outlet 49 discharges the fourth air received from the air supply flow path 93 into the third gap G3 so as to form a first air flow from the third gap G3 toward the second gap G2 and a second air flow from the third gap G3 toward the air ejection port OP1.

[0176] The fourth air injected from the air injection port OP1 prevents foreign matter such as chips from entering the machining head 10 through the third gap G3, etc. More specifically, the fourth air injected from the air injection port OP1 forms an air curtain AC around the tool T or the tool holder HD. This air curtain prevents foreign matter such as chips from entering the machining head 10 through the third gap G3, etc.

[0177] 24, the fourth air flowing from the third gap G3 to the second gap G2 prevents the oil E from entering the second gap G2 from the first gap G1 or the annular receiving space SP. In addition, the fourth air flowing from the third gap G3 to the second gap G2 pushes back the oil that has entered the second gap G2 toward the annular receiving space SP.

[0178] At least a portion of the fourth air flowing from the third gap G3 toward the second gap G2 reaches the annular receiving space SP. The air that has reached the annular receiving space SP is recovered via the third recovery passage 73.

[0179] Air (or air containing trace amounts of oil) that is not recovered by the first recovery flow path 71, the second recovery flow path 72, the third recovery flow path 73, etc. is discharged outside the processing head 10 through the gaps in the processing head 10 (see the dashed arrows in Figure 19).

[0180] (Third embodiment) A machine tool 100 according to a third embodiment will be described with reference to Figures 1 to 31. Figure 27 is a schematic perspective view showing an example of a machine tool 100 according to the third embodiment. Figure 28 is a schematic perspective view showing another example of a machine tool 100 according to the third embodiment. Figure 29 is a diagram showing a state in which a control device 140 is able to control a plurality of control target devices. Figure 30 is a diagram for explaining an example of the arrangement of a collection container 792. Figure 31 is a diagram for explaining another example of the arrangement of a collection container 792.

[0181] In the third embodiment, differences from the first and second embodiments will be mainly described. On the other hand, in the third embodiment, repeated descriptions of matters already described in the first or second embodiment will be omitted. Therefore, it goes without saying that matters already described in the first or second embodiment can be applied to the third embodiment, even if they are not explicitly described in the third embodiment.

[0182] As illustrated in Figures 27 and 29, the machine tool 100 in the third embodiment includes a machining head 10, a mixed fluid supply device 6, a recovery device 7, a workpiece support device 110 that supports the workpiece W, a moving device 120 that moves the machining head 10 relative to the workpiece support device 110, and a control device 140.

[0183] The processing head 10, the mixed fluid supply device 6, and the recovery device 7 have already been described in the first or second embodiment, so a repeated description of these configurations will be omitted.

[0184] 27 , the workpiece support device 110 has a support 111 (more specifically, a table 111a) that supports the workpiece W, and a second rotation drive device 112 that rotates the support 111 (more specifically, the table 111a) about a second axis AX2. The workpiece support device 110 may also have a tilting device 113 that tilts the table 111a about an axis AX3 that is perpendicular to the second axis AX2.

[0185] Alternatively, as illustrated in FIG. 28, the work support device 110 may have a chuck 111b that holds the work W and a second rotation drive device 112 that rotates the chuck 111b around the second axis AX2.

[0186] (Moving device 120) The moving device 120 moves the machining head 10 relative to the workpiece support device 110. The moving device 120 may be a device capable of moving the machining head 10 three-dimensionally. The moving device 120 may be capable of moving the machining head 10 along a Z-axis parallel to the vertical direction. The moving device 120 may be capable of moving the machining head 10 along an X-axis parallel to the horizontal direction. The moving device 120 may also be capable of moving the machining head 10 along a Y-axis perpendicular to both the X-axis and the Z-axis. In the example shown in FIGS. 27 and 28 , the machining head 10 is supported by the base 130 via the moving device 120.

[0187] (Control Device 140) The control device 140 controls at least the first rotation drive device 5, the mixed fluid supply device 6, and the moving device 120. Additionally, the control device 140 may control the recovery device 7.

[0188] 29 , the control device 140 includes a hardware processor 141 (hereinafter simply referred to as the “processor 141”), a memory 142, a communication circuit 144, and an input device 146 (for example, a touch panel display 146a). The processor 141, the memory 142, the communication circuit 144, and the input device 146 are connected to one another via a bus 148.

[0189] Memory 142 stores data 142a necessary for machining a workpiece and programs 142b for operating each component of machine tool 100. Memory 142 is a storage medium readable by processor 141 of control device 140. Memory 142 may be, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, or flash memory, a magnetic disk, or any other type of memory.

[0190] The input device 146 is not limited to the touch panel display 146a. For example, the control device 140 may include an input device 146 such as a button, a switch, a lever, a pointing device, or a keyboard, and a display that displays data input to the input device 146 or other information. The memory 142 may also be distributed across multiple locations. For example, part of the memory 142 may be included in cloud storage.

[0191] A plurality of computers may cooperate to function as the control device 140. In the example shown in FIG. 29 , the control device 140 includes a main control device 140a and the above-described controller 8. In other words, the main control device 140a and the controller 8 cooperate to function as the control device 140. The controller 8 operates based on instructions received from the main control device 140a. Note that if the functions of the controller 8 described in the first or second embodiment are incorporated into the main control device 140a, the controller 8 is omitted. In other words, the main control device 140a itself functions as the controller 8.

[0192] 29 , when the control device 140 transmits a first group of control commands C1 to the mixed fluid supply device 6, the mixed fluid supply device 6 receiving the first group of control commands C1 supplies the mixed fluid at a first flow rate to the plurality of bearings 3. In this way, the mixed fluid containing oil and air is supplied to the plurality of bearings 3.

[0193] In the example shown in FIG. 29, when the control device 140 transmits the second group of control commands C2 to the recovery device 7, the recovery device 7 that receives the second group of control commands C2 recovers the oil-containing fluid.

[0194] For example, the recovery device 7 that receives the second group control command C2 supplies the first air to the first ejector 75a. The first air generates a negative pressure in the first pipe 74a, and the negative pressure causes the first oil-containing fluid to be sucked through the first pipe 74a from the first recovery passage 71. When the opening degree of the first flow control valve 76a is set to the first opening degree, poor lubrication of the bearings does not occur due to the suction force of the first ejector 75a.

[0195] For example, the recovery device 7 that receives the second group control command C2 supplies the second air to the second ejector 75b. The second air generates negative pressure in the second pipe 74b, and the negative pressure causes the second oil-containing fluid to be sucked through the second pipe 74b from the second recovery passage 72. When the aperture of the second flow control valve 76b is set to the second aperture, poor lubrication of the bearings does not occur due to the suction force of the second ejector 75b.

[0196] For example, the recovery device 7 that receives the second group control command C2 supplies the third air to the third ejector 75c. The third air generates negative pressure in the third pipe 74c, and the negative pressure causes the third oil-containing fluid to be sucked from the third recovery passage 73 through the third pipe 74c.

[0197] In the example shown in FIG. 29 , when the control device 140 transmits a control command C3 to the air supply device 9, the air supply device 9 that receives the control command C3 supplies a fourth air to the outlet 49 formed in the housing 4.

[0198] A portion of the fourth air discharged from the discharge port 49 is ejected from the air ejection port OP1. An air curtain is formed by the air ejected from the air ejection port OP1. In addition, a portion of the fourth air discharged from the discharge port 49 is recovered by the recovery device 7 via the third recovery passage 73.

[0199] 29 , when the control device 140 transmits a first movement command J1 to the movement device 120, the movement device 120 that receives the first movement command J1 moves the machining head 10 relative to the workpiece support device 110. In this way, the tool T held by the rotating body 2 can be moved toward the workpiece W.

[0200] 29 , when the control device 140 transmits a first rotation command R1 to the first rotation drive device 5, the first rotation drive device 5 that receives the first rotation command R1 rotates the rotating body 2 about the first axis AX1. In this way, the workpiece W can be machined by the tool T held by the rotating body 2.

[0201] The control device 140 may be capable of controlling the second rotation drive device 112. For example, when the control device 140 transmits a second rotation command R2 to the second rotation drive device 112, the second rotation drive device 112 that receives the second rotation command R2 rotates the support tool 111 that supports the workpiece W around the second axis AX2.

[0202] The processor 141 of the control device 140 executes the program 142b stored in the memory 142, causing the control device 140 to generate control commands. Furthermore, the communication circuit 144 transmits the control commands to the devices to be controlled (more specifically, the first rotation drive device 5, the moving device 120, the mixed fluid supply device 6, the recovery device 7, the air supply device 9, the second rotation drive device 112, etc.). In this way, the processor 141 executes the program 142b, allowing the control device 140 to control the first rotation drive device 5, the moving device 120, the mixed fluid supply device 6, the recovery device 7, the air supply device 9, the second rotation drive device 112, etc.

[0203] (Arrangement of collection container 792) In the example shown in Figure 30, the machine tool 100, when viewed in a plane, comprises an outer wall 171 that surrounds the work support device 110 and the machining head 10, an opening 173 formed in the outer wall 171 through which the work passes as it is transported to the work support device 110, and a door 175 that opens and closes the opening 173.

[0204] In the example shown in Fig. 30 , collection container 792 is arranged at a position that is reachable by an operator from outside the machine tool via opening 173. In other words, collection container 792 is arranged near opening 173. In this case, the operator can easily remove the drained oil collected in collection container 792 from machine tool 100. Alternatively, as illustrated in Fig. 31 , collection container 792 may be arranged outside outer wall 171.

[0205] When the collection container 792 is located near the opening 173 or outside the outer wall 171, the conduit from the machining head 10 to the collection container 792 becomes long. As the conduit becomes longer, the pressure loss of the fluid flowing through the conduit increases, making it more difficult to optimize lubrication for each of the bearings. In the third embodiment, the suction force acting on each ejector can be individually set. Therefore, even when the conduit to the collection container 792 is long, the lubrication for each of the bearings can be optimized by appropriately setting each suction force. In particular, by setting the aperture of each flow control valve (75a, 75b, ...) in consideration of the first condition CD1 and the second condition CD2 (or the third condition CD3 and the fourth condition CD4), the suction force acting on each ejector can be easily and appropriately set.

[0206] (Method of Using the Machine Tool) A method of using the machine tool in the embodiment will be described with reference to Figures 1 to 32. Figure 32 is a flowchart showing an example of a method of using the machine tool in the embodiment.

[0207] The machine tool used in the method of using the machine tool is, for example, machine tool 100 in the third embodiment. Machine tool 100 and the components of machine tool 100 have already been explained in the first to third embodiments, so repeated explanations of machine tool 100 and the components of machine tool 100 will be omitted.

[0208] In the first step ST1, the first discharge flow rate and the second discharge flow rate are derived. The first step ST1 is a discharge flow rate deriving step.

[0209] The discharge flow rate derivation process (first step ST1) includes deriving the first discharge flow rate by measurement or simulation when the flow rate of the first oil-containing fluid discharged from the first recovery flow path 71 to outside the first recovery flow path 71 (e.g., outside the housing 4) under the above-mentioned second condition CD2 (see Figure 5 or Figure 9) is defined as the first discharge flow rate.

[0210] The discharge flow rate derivation process (first step ST1) includes deriving the second discharge flow rate by measurement or simulation when the flow rate of the second oil-containing fluid discharged from the second recovery flow path 72 to outside the second recovery flow path 72 (e.g., outside the housing 4) under the above-mentioned second condition CD2 (see Figure 5 or Figure 9) is defined as the second discharge flow rate.

[0211] In addition, in a case where machine tool 100 includes third recovery passage 73, air supply passage 93, and air injection port OP1, the discharge flow rate derivation step (first step ST1) may include, when the flow rate of the first oil-containing fluid discharged from first recovery passage 71 to the outside of first recovery passage 71 (e.g., outside of housing 4) is defined as the first discharge flow rate under the above-mentioned fourth condition CD4 (see FIG. 16 ; the fourth condition CD4 is one aspect of the second condition CD2), deriving the first discharge flow rate by measurement or simulation. Furthermore, in a case where the flow rate of the second oil-containing fluid discharged from second recovery passage 72 to the outside of second recovery passage 72 (e.g., outside of housing 4) is defined as the second discharge flow rate under the above-mentioned fourth condition CD4 (see FIG. 16 ), the discharge flow rate derivation step (first step ST1) may include, when the flow rate of the second oil-containing fluid discharged from second recovery passage 72 to the outside of second recovery passage 72 (e.g., outside of housing 4) is defined as the second discharge flow rate, deriving the second discharge flow rate by measurement or simulation.

[0212] In the second step ST2, the first recovery flow rate and the second recovery flow rate are derived. The second step ST2 is a recovery flow rate deriving step.

[0213] The recovery flow rate derivation process (second step ST2) includes deriving the first recovery flow rate by measurement or simulation when the flow rate of the first oil-containing fluid flowing through the first pipeline 74a is defined as the first recovery flow rate under the above-mentioned first condition CD1 (see Figure 4 or Figure 8).

[0214] The recovery flow rate derivation process (second step ST2) includes deriving the second recovery flow rate by measurement or simulation when the flow rate of the second oil-containing fluid flowing through the second pipeline 74b is defined as the second recovery flow rate under the above-mentioned first condition CD1 (see Figure 4 or Figure 8).

[0215] In addition, when the machine tool 100 includes the third recovery passage 73, the air supply passage 93, and the air injection port OP1, the recovery flow rate deriving step (second step ST2) may include deriving the first recovery flow rate by measurement or simulation when the flow rate of the first oil-containing fluid flowing through the first pipe 74a is defined as the first recovery flow rate under the above-mentioned third condition CD3 (see FIG. 15 . Note that the third condition CD3 is one aspect of the first condition CD1). Furthermore, in the recovery flow rate deriving step (second step ST2), when the flow rate of the second oil-containing fluid flowing through the second pipe 74b is defined as the second recovery flow rate under the above-mentioned third condition CD3 (see FIG. 15 ), the recovery flow rate deriving step (second step ST2) may include deriving the second recovery flow rate by measurement or simulation.

[0216] In a third step ST3, the opening degrees of the first flow control valve 76a and the second flow control valve 76b are derived. The third step ST3 is an opening degree derivation step.

[0217] The opening degree deriving step (third step ST3) includes deriving a first opening degree of the first flow control valve 76a such that the ratio of the first recovery flow rate to the first discharge flow rate falls within a predetermined range. For example, the opening degree deriving step includes deriving a first opening degree of the first flow control valve 76a such that the first recovery flow rate falls within a range of 1 to 1.5 times the first discharge flow rate (more preferably, such that the first recovery flow rate falls within a range of 1 to 1.2 times the first discharge flow rate). The first opening degree may be derived by calculating a correlation between the opening degree of the first flow control valve 76a and the first recovery flow rate and based on the correlation. Alternatively, the first opening degree may be derived by trial and error.

[0218] The opening degree deriving step (third step ST3) includes deriving a second opening degree of the second flow control valve 76b such that the ratio of the second recovery flow rate to the second discharge flow rate falls within a predetermined range. For example, the opening degree deriving step includes deriving a second opening degree of the second flow control valve 76b such that the second recovery flow rate falls within a range of 1 to 1.5 times the second discharge flow rate (more preferably, such that the second recovery flow rate falls within a range of 1 to 1.2 times the second discharge flow rate). The second opening degree may be derived by calculating a correlation between the opening degree of the second flow control valve 76b and the second recovery flow rate and based on the correlation. Alternatively, the second opening degree may be derived by trial and error.

[0219] In addition, when the machine tool 100 is equipped with the third recovery passage 73, the air supply passage 93, and the air injection port OP1, the opening degree derivation process (third step ST3) may include deriving the opening degree of the third flow control valve 76c (hereinafter referred to as the "third opening degree") and the opening degree of the fourth flow control valve 96 (hereinafter referred to as the "fourth opening degree") so that the flow rate of the fourth air ejected from the discharge port 49 (see Figure 14) is greater than the flow rate of air injected from the air injection port OP1 (see Figure 14).

[0220] More specifically, the opening degree derivation process (third step ST3) may include deriving the third opening degree of the third flow control valve 76c and the fourth opening degree of the fourth flow control valve 96 so that (1) the flow rate of the fourth air discharged from the discharge port 49 (see FIG. 14) is greater than the flow rate of the air sprayed from the air injection port OP1 (see FIG. 14), and (2) the flow rate of the air sprayed from the air injection port OP1 is equal to or greater than the above-mentioned third flow rate (more specifically, equal to or greater than the design lower limit flow rate for forming an air curtain).

[0221] The first step ST1 to the third step ST3 described above are performed, for example, before the spindle lubrication device 1 (or the machine tool 100) is shipped to a customer. More specifically, the first step ST1 to the third step ST3 described above are performed before the machine tool 100 is installed in the customer's factory. Furthermore, the fourth step ST4 to the sixth step ST6 described below are performed, for example, after the machine tool 100 is installed in the customer's factory. More specifically, the fourth step ST4 to the sixth step ST6 described below are performed when the machine tool 100 is machining a workpiece.

[0222] In a fourth step ST4, a mixed fluid containing oil and air is supplied to the plurality of bearings 3. The fourth step ST4 is a mixed fluid supplying step. The mixed fluid supplying step is performed using a mixed fluid supplying device 6.

[0223] In fifth step ST5, the recovery device 7 is operated. Fifth step ST5 is a recovery device operation step. The recovery device operation step includes operating the recovery device 7 in a state where the aperture of the first flow control valve 76a is set to the above-mentioned first aperture and the aperture of the second flow control valve 76b is set to the above-mentioned second aperture. Note that, in a case where the machine tool 100 is equipped with the third recovery passage 73, the recovery device operation step includes recovering, via the third recovery passage 73, a third oil-containing fluid containing oil that has passed through the first bearing 31a without being recovered by the first recovery passage 71. More specifically, the recovery device operation step may include operating the recovery device 7 in a state where the aperture of the third flow control valve 76c is set to the above-mentioned third aperture.

[0224] In a sixth step ST6, the workpiece is machined. The sixth step ST6 is a workpiece machining step. In the workpiece machining step, the workpiece W is machined by a tool T that is held by the rotating body 2 and rotates about the first axis AX1.

[0225] The fourth step ST4 to the sixth step ST6 are executed in parallel. More specifically, during the execution of the workpiece machining process, the mixed fluid containing oil and air is supplied to the plurality of bearings 3 using the mixed fluid supply device 6, and the recovery device 7 is operated in a state where the aperture of the first flow control valve 76a is set to the above-mentioned first aperture and the aperture of the second flow control valve 76b is set to the above-mentioned second aperture.

[0226] When the recovery device 7 is operated with the opening degree of the first flow control valve 76a set to the first opening degree, the first oil-containing fluid is suitably recovered via the first recovery flow path 71 and the first pipe 74a. Furthermore, poor lubrication of the bearings does not occur due to the suction force of the first ejector 75a. The first oil-containing fluid that has passed through the first ejector 75a is preferably sent to the exhaust cleaner 791 via the exhaust pipe 78.

[0227] When the recovery device 7 is operated with the second flow control valve 76b set to the second opening, the second oil-containing fluid is preferably recovered via the second recovery passage 72 and the second pipe 74b. Furthermore, poor lubrication of the bearings does not occur due to the suction force of the second ejector 75b. The second oil-containing fluid that has passed through the second ejector 75b is preferably sent to the exhaust cleaner 791 via the exhaust pipe 78.

[0228] In addition, when the machine tool 100 is equipped with an air supply passage 93 and an air injection port OP1, it is preferable that the workpiece machining process (sixth step ST6) be performed in the following states: (1) fourth air is supplied to the air supply passage 93 provided in the housing; (2) a portion of the fourth air is sprayed as an air curtain from the air injection port OP1 formed between the rotating body 2 and the tip 46 of the housing 4; and (3) the flow rate of the fourth air supplied to the air supply passage 93 is greater than the flow rate of the air injected from the air injection port OP1.

[0229] More specifically, it is preferable that the recovery device 7 is operated with the aperture of the third flow control valve 76c set to the above-described third aperture, and the air supply device 9 is operated with the aperture of the fourth flow control valve 96 set to the above-described fourth aperture. When the recovery device 7 is operated with the aperture of the third flow control valve 76c set to the above-described third aperture, during the execution of the workpiece machining process (sixth step ST6), a third oil-containing fluid containing oil that has passed through the first bearing 31a without being recovered by the first recovery passage 71 is recovered via the third recovery passage 73. Furthermore, when the recovery device 7 is operated with the aperture of the third flow control valve 76c set to the above-described third aperture, and the air supply device 9 is operated with the aperture of the fourth flow control valve 96 set to the above-described fourth aperture, (1) mixing of oil with the air sprayed from the air jet orifice OP1 is prevented or suppressed, and (2) an air curtain is suitably formed by the air sprayed from the air jet orifice OP1.

[0230] The present invention is not limited to the above-described embodiments or modifications, and it is clear that each embodiment or modification can be appropriately modified or changed within the scope of the technical concept of the present invention. Furthermore, various techniques used in each embodiment or modification can be applied to other embodiments or modifications as long as no technical contradiction occurs. Furthermore, optional additional configurations in each embodiment or modification can be omitted as appropriate.

[0231] 27, the machine tool 100 is a vertical machining center. Alternatively, the machine tool 100 in the embodiment may be a horizontal machining center. Furthermore, the machine tool 100 may be a multi-tasking machine capable of performing machining other than cutting.

[0232] 1, 1A, 1A', 1B... spindle lubrication device, 2... rotating body, 3... bearing, 4... housing, 4a... front end portion of housing, 4b... rear end portion of housing, 4c... middle portion of housing, 4f... end surface of housing, 5... first rotation drive device, 6... mixed fluid supply device, 7... recovery device, 8... controller, 9... air supply device, 10... machining head, 11a... first flow meter, 11b... second flow meter, 12... main air flow path, 13... on-off valve, 13a... first on-off valve, 13b... second on-off valve, 13c... third on-off valve, 13d... fourth on-off valve, 13e... fifth on-off valve, 14... mounting portion drive device, 2 0...rotating shaft, 21...rotating shaft main body, 21n...inner peripheral surface of rotating body, 22...rear end portion of rotating body, 23...middle portion of rotating body, 24...tip portion of rotating body, 25...first portion of rotating body, 25a...step surface of rotating body, 25u...first outer peripheral surface, 26...second portion of rotating body, 26u...second outer peripheral surface, 28...mounting portion, 31...front bearing, 31a...first bearing, 31c...third bearing, 32a, 32c...inner ring, 33a, 33c...outer ring, 34a, 34c...rolling element, 36...rear bearing, 36b...second bearing, 37b...outer ring, 40b...end plate of housing, 40c...side wall of housing, 41...house Third part of housing, 42...Fourth part of housing, 43...Base of fourth part, 44...Annular protrusion, 44a...First surface, 44b...Second surface, 44f...Third surface, 45...Opening, 46...Tip part of housing, 47...Flange, 49...Discharge port, 51...Stator, 53...Rotor, 61...Oil tank, 62...Pump, 63...Second air supply pipe, 64...Mixer, 66...Supply flow passage, 67...Fifth flow control valve, 68...Mixed fluid supply pipe, 71...First recovery passage, 71p...Outlet port, 72...Second recovery passage, 73...Third recovery passage, 73p...Outlet port, 74...Pipe, 74a...First pipe, 75a...Second pipe, 76a...Second recovery passage, 77a...Third recovery passage, 78a...Third pipe, 79a...Second pipe, 80a...Second pipe, 81a...Second pipe, 82a...Second pipe, 83a...Second recovery passage, 84a...Second pipe, 85a...Second pipe, 86a...Second pipe, 87a...Second pipe, 88a...Second pipe, 89a...Second pipe, 90a...Second pipe, 91a...Second pipe, 92a...Second pipe, 93a...Third pipe, 94a...Second pipe, 95a...Second pipe, 96a...Second pipe, 97a...Second pipe, 98a...Second pipe, 99a...Second pipe, 100a...Second pipe, 101a...Second pipe, 4b...second pipe line, 74c...third pipe line, 75...ejector, 75'...negative pressure generator, 75a...first ejector, 75b...second ejector, 75c...third ejector, 76a...first flow control valve, 76b...second flow control valve, 76c...third flow control valve, 77a...first air flow path, 77b...second air flow path, 77c...third air flow path, 78...exhaust pipe line, 80...processor, 82...memory, 84...communication circuit, 88...bus, 91...air supply pipe, 93...air supply flow path, 93p...inlet port, 96...fourth flow control valve, 100...machine tool, 110...workpiece support device, 111...support tool,111a...table, 111b...chuck, 112...second rotation drive device, 113...tilting device, 120...movement device, 130...base, 140...control device, 140a...main control device, 141...hardware processor, 142...memory, 142a...data, 142b...program, 144...communication circuit, 146...input device, 146a...touch panel display, 148...bus, 171...outer wall, 173...opening, 175...door, 291...rod-shaped member, 293...urging member, 440a...first wall, 440b...second wall, 441...annular protrusion, 751, 751a, 751b, 751c...inlet port, 752, 752a, 7 52b, 752c...outlet port, 753, 753a, 753b, 753c...vacuum port, 791...exhaust cleaner, 792...collection container, AC...air curtain, AS, AS1, AS2, AT...air source, C...drive command, C1, C2, C3...control command, CN...corner, CP1...first part, CP2...second part, CT...notch, E, E1...oil, G...gap, G1...first gap, G2...second gap, G3...third gap, HD...tool holder, J1...first movement command, OP1...air injection port, R1...first rotation command, R2...second rotation command, SP...annular receiving space, T...tool, V1...first annular groove, V2...second annular groove, W...workpiece,

Claims

1. A rotating body for holding a tool, a plurality of bearings including a first bearing and a second bearing, a housing for supporting the rotating body rotatably about a first axis via the plurality of bearings, a mixed fluid supply device for supplying a mixed fluid containing oil and air to the plurality of bearings, and a recovery device for recovering an oil-containing fluid containing the oil, wherein the recovery device is provided in the housing and comprises a plurality of recovery flow paths for recovering the oil-containing fluid from the plurality of bearings, a plurality of ejectors disposed outside the housing, and a plurality of flow control valves, wherein the plurality of recovery flow paths include a first recovery flow path for recovering a first oil-containing fluid discharged mainly from at least one bearing including the first bearing, and a second recovery flow path for recovering a second oil-containing fluid discharged mainly from at least one bearing including the second bearing, and the plurality of ejectors are a first ejector for sucking the first oil-containing fluid from the first recovery flow path by generating a negative pressure by a first air supplied from a first air flow path, a second ejector that sucks the second oil-containing fluid from the second recovery passage by generating a negative pressure by a second air supplied from a second air passage, wherein the plurality of flow control valves include: a first flow control valve that adjusts a flow rate of the first air supplied from the first air passage to the first ejector, and a second flow control valve that adjusts a flow rate of the second air supplied from the second air passage to the second ejector.

2. The fluid mixing device further comprises a plurality of pipelines including a first pipeline fluidly connecting the first recovery flow path and the first ejector, and a second pipeline fluidly connecting the second recovery flow path and the second ejector, wherein the plurality of pipelines are fluidly connected to the plurality of recovery flow paths, respectively, and a flow rate of the first oil-containing fluid flowing through the first pipeline under a first condition in which the mixed fluid is supplied from the mixed fluid supply device to the plurality of bearings at a first flow rate is defined as a first recovery flow rate, and a flow rate of the first oil-containing fluid discharged from the first recovery flow path to the outside of the first recovery flow path under a second condition that differs from the first condition only in that the plurality of pipelines are fluidly separated from the plurality of recovery flow paths is defined as a first discharge flow rate, and an opening degree of the first flow control valve is set so that the first recovery flow rate is within a range of 1 to 1.5 times the first discharge flow rate, 2. The spindle lubrication device of a machine tool according to claim 1, wherein when a flow rate of the second oil-containing fluid flowing through the second pipeline under the first condition is defined as a second recovery flow rate, and a flow rate of the second oil-containing fluid discharged from the second recovery flow path to the outside of the second recovery flow path under the second condition is defined as a second discharge flow rate, an opening degree of the second flow control valve is set so that the second recovery flow rate is within a range of 1 to 1.5 times the second discharge flow rate.

3. A spindle lubrication device for a machine tool as described in claim 2, wherein the multiple recovery passages include a third recovery passage that recovers a third oil-containing fluid containing the oil that has passed through the first bearing without being recovered by the first recovery passage, the multiple pipelines include a third pipeline that fluidly connects the third recovery passage and a third ejector, the multiple ejectors include the third ejector that generates negative pressure in the third pipeline by third air supplied from a third air passage and sucks in the third oil-containing fluid from the third recovery passage through the third pipeline, and the multiple flow control valves include a third flow control valve that adjusts the flow rate of the third air supplied from the third air passage to the third ejector.

4. A spindle lubrication device for a machine tool as described in claim 1, wherein the multiple recovery passages include a third recovery passage that recovers a third oil-containing fluid containing the oil that has passed through the first bearing without being recovered by the first recovery passage, the multiple ejectors include a third ejector that sucks the third oil-containing fluid from the third recovery passage by generating negative pressure with third air supplied from a third air passage, and the multiple flow control valves include a third flow control valve that adjusts the flow rate of the third air supplied to the third ejector from the third air passage.

5. The spindle lubrication device for a machine tool according to claim 4, wherein the rotating body has: a rear end; a front end portion for holding the tool; a first portion supporting an inner ring of the first bearing and having a first outer peripheral surface; a second portion having a second outer peripheral surface smaller in diameter than the first outer peripheral surface, and arranged on the first direction side of the first portion when a direction from the rear end toward the front end is defined as a first direction; and a step surface connecting the first outer peripheral surface and the second outer peripheral surface; and the housing has: a third portion supporting an outer ring of the first bearing; and a fourth portion defining an annular receiving space that receives the oil from a first gap between the first portion and the third portion, the fourth portion having an opening for guiding the oil from the annular receiving space to the third recovery passage, a second gap fluidly communicating with the first gap is formed between the housing and the step surface, and a third gap fluidly communicating with the second gap is formed between the housing and the second outer peripheral surface.

6. The spindle lubrication device for a machine tool according to claim 5, wherein the fourth portion has an annular protrusion protruding in a direction away from the first shaft, the annular protrusion facing both the stepped surface and the annular receiving space.

7. A spindle lubrication device for a machine tool as claimed in any one of claims 4 to 6, further comprising an air supply device comprising: an air source arranged outside the housing; an air supply flow path provided in the housing; an air supply pipe connecting the air source to the air supply flow path and supplying a fourth air to the air supply flow path; and a fourth flow control valve adjusting the flow rate of the fourth air supplied from the air supply pipe to the air supply flow path, wherein an air injection port is formed between the rotating body and a tip end of the housing, and the housing is formed with an outlet port for discharging the fourth air received from the air supply flow path into the gap so that both a first flow directed from the gap between the rotating body and the housing toward the third recovery flow path and a second flow directed from the gap toward the air injection port are formed.

8. The fluid communication device further comprises a plurality of pipelines including a first pipeline fluidly connecting the first recovery flow path and the first ejector, a second pipeline fluidly connecting the second recovery flow path and the second ejector, and a third pipeline fluidly connecting the third recovery flow path and the third ejector, wherein the plurality of pipelines are fluidly connected to the plurality of recovery flow paths, respectively, and a flow rate of the first oil-containing fluid flowing through the first pipeline under a third condition in which the mixed fluid is supplied from the mixed fluid supply device to the plurality of bearings at a first flow rate, and the fourth air is supplied to the air supply flow path at a second flow rate, is defined as a first recovery flow rate, and a flow rate of the first oil-containing fluid discharged from the first recovery flow path to the outside of the first recovery flow path under a fourth condition that differs from the third condition only in that the plurality of pipelines are fluidly separated from the plurality of recovery flow paths is defined as a first discharge flow rate, and an opening degree of the first flow control valve is set so that the first recovery flow rate is within a range of 1 to 1.5 times the first discharge flow rate, 8. The spindle lubrication device for a machine tool according to claim 7, wherein when a flow rate of the second oil-containing fluid flowing through the second pipeline under the third condition is defined as a second recovery flow rate, and a flow rate of the second oil-containing fluid discharged from the second recovery flow path to the outside of the second recovery flow path under the fourth condition is defined as a second discharge flow rate, an opening degree of the second flow control valve is set so that the second recovery flow rate is within a range of 1 to 1.5 times the second discharge flow rate.

9. A spindle lubrication device for a machine tool as described in claim 8, wherein the opening degree of the third flow control valve and the opening degree of the fourth flow control valve are set so that the flow rate of the fourth air discharged from the discharge port is greater than the flow rate of air injected from the air injection port.

10. A machining head having a rotating body for holding a tool, a plurality of bearings including a first bearing and a second bearing, a housing for rotatably supporting the rotating body via the plurality of bearings, and a first rotary drive device for rotating the rotating body around a first axis, a mixed fluid supplying device for supplying a mixed fluid containing oil and air to the plurality of bearings, a recovery device for recovering an oil-containing fluid containing the oil, a work support device for supporting a work, a moving device for moving the machining head relative to the work support device, and a control device for controlling at least the first rotary drive device, the mixed fluid supplying device, and the moving device, wherein the recovery device is provided in the housing and comprises a plurality of recovery flow paths for recovering the oil-containing fluid from the plurality of bearings, a plurality of ejectors arranged outside the housing, and a plurality of flow control valves, wherein the plurality of recovery flow paths are: a first recovery flow path for recovering a first oil-containing fluid discharged mainly from at least one bearing including the first bearing, and a second recovery passage that recovers a second oil-containing fluid mainly discharged from at least one bearing including the second bearing, wherein the plurality of ejectors include: a first ejector that sucks the first oil-containing fluid from the first recovery passage by generating a negative pressure with a first air supplied from a first air passage, and a second ejector that sucks the second oil-containing fluid from the second recovery passage by generating a negative pressure with a second air supplied from a second air passage, and the plurality of flow control valves include: a first flow control valve that adjusts a flow rate of the first air supplied from the first air passage to the first ejector, and a second flow control valve that adjusts a flow rate of the second air supplied from the second air passage to the second ejector.

11. A machine tool as described in claim 10, further comprising, in a plan view, an outer wall surrounding the work support device and the machining head, an opening formed in the outer wall through which the work is transported to the work support device, and a door for opening and closing the opening, wherein the recovery device comprises an exhaust pipe that receives exhaust from the multiple ejectors, and a recovery container fluidly connected to the exhaust pipe, and the recovery container is positioned at a position reachable by an operator from outside the machine tool via the opening, or is positioned outside the outer wall.

12. The machine tool according to claim 10 or 11, further comprising a plurality of pipelines including a first pipeline fluidly connecting the first recovery passage and the first ejector, and a second pipeline fluidly connecting the second recovery passage and the second ejector.

13. When a flow rate of the first oil-containing fluid flowing through the first pipeline under a first condition in which the plurality of pipelines are fluidly connected to the plurality of recovery flow paths, respectively, and a first flow rate of the mixed fluid is supplied from the mixed fluid supply device to the plurality of bearings is defined as a first recovery flow rate, and a flow rate of the first oil-containing fluid discharged from the first recovery flow path to the outside of the first recovery flow path under a second condition that differs from the first condition only in that the plurality of pipelines are fluidly separated from the plurality of recovery flow paths is defined as a first discharge flow rate, an opening degree of the first flow control valve is set so that the first recovery flow rate is within a range of 1 to 1.5 times the first discharge flow rate, 13. The machine tool according to claim 12, wherein when a flow rate of the second oil-containing fluid flowing through the second pipeline under the first condition is defined as a second recovery flow rate, and a flow rate of the second oil-containing fluid discharged from the second recovery passage to the outside of the second recovery passage under the second condition is defined as a second discharge flow rate, an opening degree of the second flow control valve is set so that the second recovery flow rate is within a range of 1 to 1.5 times the second discharge flow rate.

14. A method of using a machine tool according to claim 12, comprising the steps of: under a second condition in which the plurality of pipelines are fluidly separated from the plurality of recovery flow paths and the mixed fluid is supplied from the mixed fluid supply device to the plurality of bearings at a first flow rate, when a flow rate of the first oil-containing fluid discharged from the first recovery flow path to the outside of the first recovery flow path is defined as a first discharge flow rate, deriving the first discharge flow rate by measurement or simulation; under the second condition in which the flow rate of the second oil-containing fluid discharged from the second recovery flow path to the outside of the second recovery flow path is defined as a second discharge flow rate, deriving the second discharge flow rate by measurement or simulation; and under a first condition in which the plurality of pipelines are fluidly connected to the plurality of recovery flow paths, respectively, and the mixed fluid is supplied from the mixed fluid supply device to the plurality of bearings at the first flow rate, when a flow rate of the first oil-containing fluid flowing through the first pipeline is defined as a first recovery flow rate, deriving the first recovery flow rate by measurement or simulation. a step of deriving the second recovery flow rate by measuring or simulating, when a flow rate of the second oil-containing fluid flowing through the second pipeline under the first condition is defined as a second recovery flow rate; a step of deriving a first aperture of the first flow control valve such that a ratio of the first recovery flow rate to the first discharge flow rate is within a predetermined range; a step of deriving a second aperture of the second flow control valve such that a ratio of the second recovery flow rate to the second discharge flow rate is within a predetermined range; a step of supplying the mixed fluid to the plurality of bearings using the mixed fluid supply device; a step of operating the recovery device with the aperture of the first flow control valve set to the first aperture and the aperture of the second flow control valve set to the second aperture; and a step of machining the workpiece by the tool held by the rotating body and rotating about the first axis.

15. A method of using a machine tool as described in claim 14, wherein the step of operating the recovery device includes recovering, via a third recovery passage, a third oil-containing fluid containing the oil that has passed through the first bearing without being recovered by the first recovery passage, and the step of machining the workpiece is carried out in a state in which a fourth air is supplied to an air supply passage provided in the housing, a portion of the fourth air is sprayed as an air curtain from an air injection port formed between the rotating body and the tip of the housing, and a flow rate of the fourth air supplied to the air supply passage is greater than the flow rate of air sprayed from the air injection port.

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