Spindle unit of a machine tool

Abstract

To provide a main spindle device of a machine tool which can avoid interference between a main spindle device and an automatic tool changer effectively by using an air supply plate.SOLUTION: A main spindle device 1 of a machine tool 10 includes: a rotary main spindle 2 formed with a tool attachment part 21; a housing 3 rotatably supporting the rotary main spindle 2 with a bearing 31; an air supply plate 4 having an annular part 41 and multiple protruding parts 42; and a cleaning air supply passage 5 for supplying cleaning air A1 to the tool attachment part 21. The cleaning air supply passage 5 has: first supply passages 51 formed at the housing 3; second supply passages 52 formed at the protruding parts 42; a third supply passage 53 formed in an annular shape between an outer periphery of a tip of the rotary main spindle 2 and the annular part 41; and fourth supply passages 54 which are formed at a tip of the rotary main spindle 2 to blow the cleaning air A1 to the tool attachment part 21.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] The spindle device of a machine tool holds and rotates a tool to perform various processes on a workpiece. The tool held by the spindle device is replaced with a tool required as appropriate by an automatic tool changer (ATC) or the like. When replacing the tool mounted on the tool mounting portion of the spindle device, coolant (cutting fluid), air, etc. are used so that foreign matter such as chips does not adhere to the tool mounting portion in the spindle device.

[0003] For example, in the spindle device of the machine tool of Patent Document 1, it is described that the taper hole at the tip of the spindle as the tool mounting portion is cleaned by discharging air. In this spindle device, it is described that the taper hole and the tool are cleaned and the tool from biting is prevented, and at the time of clamping the tool, the air blow flow path is closed to prevent the cutting fluid from flowing back from the taper hole to the air blow flow path.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When replacing the tool mounted on the tool mounting portion of the spindle device, the automatic tool changer approaches the tool mounting portion. Also, a structure for preventing chips from adhering to the tool mounting portion by blowing air is formed around the tool mounting portion. In this case, in order to effectively avoid interference between the spindle device and the automatic tool changer, further ingenuity is required in the structure of the tool mounting portion.

[0006] This invention has been made in view of the above problems, and aims to provide a spindle device for a machine tool that can effectively avoid interference between the spindle device and the automatic tool changer by using an air supply plate. [Means for solving the problem]

[0007] One aspect of the present invention is, A spindle device of a machine tool, configured such that cleaning air is supplied to the tool mounting section where the tool holder is attached, The rotating main shaft on which the tool mounting portion is formed, A housing that rotatably supports the aforementioned rotating main shaft by bearings, An air supply plate is attached to the tip of the housing and forms an annular plate-side gap between itself and the outer circumference of the tip of the rotating spindle, allowing the rotating spindle to rotate. It includes a cleaning air supply passage for supplying the cleaning air to the tool mounting section, The aforementioned air supply plate is An annular portion arranged on the outer circumference of the tip of the main rotating shaft, The annular portion has one or more protrusions projecting radially outward from a part of its circumferential direction, The aforementioned cleaning air supply path is A first supply channel formed in the housing, A second supply passage formed in the protruding portion so as to communicate with the first supply passage, A third supply passage is formed in an annular shape between the outer circumference of the tip of the rotating main shaft and the annular portion so as to communicate with the second supply passage, The spindle device of a machine tool has a fourth supply passage formed at the tip of the rotating spindle so as to communicate with the third supply passage, and which blows the cleaning air out to the tool mounting section. [Effects of the Invention]

[0008] In the spindle unit of the aforementioned machine tool, a protrusion is formed on the air supply plate attached to the tip of the housing, and cleaning air is blown out through this protrusion. Specifically, the cleaning air supply passage for supplying cleaning air to the tool mounting section is formed as the first to fourth supply passages, extending from the housing through the protrusion to the tool mounting section of the rotating spindle.

[0009] Furthermore, since the second supply channel is formed in a protrusion located in a part of the circumferential direction of the annular portion, a circumferential space can be formed in the remaining circumferential portion where no protrusion is located on the radially outer side of the annular portion. As a result, when replacing a tool holder attached to the tool mounting portion of the spindle unit, even when the automatic tool changer approaches the tool mounting portion, interference between the spindle unit and the automatic tool changer can be effectively avoided by utilizing the circumferential space.

[0010] Therefore, according to the spindle device of the machine tool in the above-described embodiment, interference between the spindle device and the automatic tool changer can be effectively avoided by using an air supply plate. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view showing a machine tool equipped with a spindle device according to an embodiment. [Figure 2] This is a plan view showing the spindle device according to the embodiment, as viewed from the tip side of the central axis of the rotating spindle. [Figure 3] This is a cross-sectional view taken along line III-III in Figure 2, showing the circumferential position where the cleaning air supply passage is formed in the embodiment. [Figure 4] This is a cross-sectional view taken along line IV-IV in Figure 2, showing the circumferential position where the air supply passage for preventing ingress is formed in the embodiment. [Figure 5] Figure 3 is a cross-sectional view of VV showing the formation location of the cleaning air supply passage according to the embodiment. [Figure 6]FIG. 4 is a cross-sectional view taken along line VI-VI showing the formation position of the air supply passage for preventing intrusion according to the embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0012] (Embodiment) 1. Configuration of Machine Tool 10 The machine tool 10 provided with the spindle device 1 will be described with reference to FIG. 1. The machine tool 10 provided with the spindle device 1 is configured as a horizontal machining center or the like in which the central axis CL of the rotating spindle 2 of the spindle device 1 is oriented in the horizontal direction. The machine tool 10 includes a column 12 that moves the spindle device 1 in the Y-axis direction (vertical direction, indicated by the symbol Y), a Z-axis moving body 13 that is disposed on the column 12 and moves the spindle device 1 in the Z-axis direction (the direction of the central axis CL of the rotating spindle 2, indicated by the symbol Z), an X-axis moving table 14 that moves a workpiece to be machined by the rotating spindle 2 in the X-axis direction (a direction orthogonal to both the Y-axis direction and the Z-axis direction, indicated by the symbol X), a rotating table 15 that rotates the X-axis moving table 14 about an axis parallel to the Y-axis direction, a bed 11 on which the column 12 and the rotating table 15 are disposed, and the like.

[0013] Although not shown in the figure, an automatic tool changer (ATC) for exchanging the tool holder 8 attached to the tool mounting portion 21 of the spindle device 1 is installed around the machine tool 10. The automatic tool changer includes a changer arm that attaches and detaches the tool holder 8 to and from the tool mounting portion 21, a tool magazine that holds a plurality of tool holders 8 and can change the tool holder 8 gripped by the changer arm, and the like. The tool holder 8 is configured to be able to hold various tools 81. The plurality of tool holders 8 have a common shape and can be exchanged between the tool mounting portion 21 of the spindle device 1 and the tool magazine while holding various tools 81.

[0014] As shown in FIGS. 1 and 2, the tool holder 8 has a flange portion 83 facing a contact end surface 212, which will be described later, of the tool mounting portion 21 of the spindle device 1, and a shaft portion 82 inserted into a mounting recess 211, which will be described later, of the tool mounting portion 21 of the spindle device 1. The tool 81 is disposed on the side opposite to the side where the shaft portion 82 is formed in the axial direction of the tool holder 8.

[0015] 2. Configuration of Spindle Device 1 The spindle device 1 will be described with reference to FIGS. 2 to 6. Here, FIG. 2 shows the spindle device 1 as viewed from the tip side Z1 of the central axis CL of the rotating spindle. FIG. 3 shows a cross-section of the formation positions in the circumferential direction C of the first supply path 51, the second supply path 52, and the fourth supply path 54 of the cleaning air supply path 5, which will be described later, in FIG. 2. FIG. 4 shows a cross-section of the formation positions in the circumferential direction C of the axial portion 61 and the radial portion 62 of the air supply path 6 for preventing intrusion, which will be described later, in FIG. 2.

[0016] FIG. 5 shows a cross-section of the formation positions of the second supply path 52 and the fourth supply path 54 of the cleaning air supply path 5 in the direction Z of the central axis CL in FIG. 3. FIG. 6 shows a cross-section of the formation positions of the axial portion 61 and the radial portion 62 of the air supply path 6 for preventing intrusion in the direction Z of the central axis CL in FIG. 4.

[0017] As shown in FIGS. 2 and 3, the spindle device 1 of the machine tool 10 includes a rotating spindle 2 in which a tool mounting portion 21 is formed, and a housing 3 that rotatably supports the rotating spindle 2 by bearings 31. A tool holder 8 for holding the tool 81 is mounted on the tool mounting portion 21. The tool mounting portion 21 is configured to be supplied with cleaning air A1 for preventing foreign matters such as chips from adhering to the tool mounting portion 21.

[0018] The rotating spindle 2 is rotationally driven by a rotational drive source such as a motor, and rotates the tool holder 8 and tool 81 mounted on the tool mounting section 21. The tool mounting section 21 is formed at the center of the rotating spindle 2 around its central axis CL, and the shaft portion 82 of the tool holder 8 is mounted thereon. The rotating spindle 2 has a spindle center 22 located in the center including the central axis CL, a spindle outer periphery 23 arranged on the outer circumference of the spindle center 22, and a spindle cap portion 24 arranged on the tip side Z1 of the spindle center 22 and the spindle outer periphery 23. Here, tip side Z1 refers to the side of the rotating spindle 2 in the direction Z of the central axis CL where the tool holder 8 is mounted relative to the tool mounting section 21 of the rotating spindle 2.

[0019] The tool mounting portion 21 in this embodiment has a mounting structure for a tool holder 8 known as so-called two-face restraint, and holds the tool holder 8 by contacting both the tapered surface of the shaft portion 82 of the tool holder 8 and the end face of the flange portion 83 of the tool holder 8. The tool mounting portion 21 is formed recessed from the tip surface of the rotating spindle 2 and has a mounting recess 211 into which the shaft portion 82 of the tool holder 8 is inserted, and a contact tip surface 212 formed on the tip surface of the rotating spindle 2 and into which the end face of the flange portion 83 of the tool holder 8 contacts. The tapered surface of the shaft portion 82 of the tool holder 8 contacts at least one of the outer and inner circumferential surfaces of the mounting recess 211, and the end face of the flange portion 83 of the tool holder 8 contacts the contact tip surface 212.

[0020] As shown in Figures 2 and 4, the mounting recess 211 is formed by an annular recess extending from the tip side Z1 to the base side Z2 of the rotating spindle 2 between the tip side portion of the spindle outer circumference 23 and the spindle cap portion 24. The contact tip surface 212 is formed as the surface of the tip side Z1 of the spindle cap portion 24. Although details are omitted, the spindle center 22 and the spindle outer circumference 23 are relatively movable in the direction Z of the central axis CL of the rotating spindle 2 in order to hold the shaft portion 82 of the tool holder 8. The shaft portion 82 of the tool holder 8 is held in the state inserted into the mounting recess 211 by the relative movement of the spindle center 22 and the spindle outer circumference 23 in the direction Z of the central axis CL.

[0021] The tool mounting portion 21 may have a mounting structure for the tool holder 8, known as a so-called single-face restraint. In this case, the tool mounting portion 21 is composed of a mounting recess 211, and the tool holder 8 is held in a state where at least one of the outer and inner circumferential surfaces of the mounting recess 211 is in contact with the tapered surface of the shaft portion 82 of the tool holder 8.

[0022] As shown in Figure 2, the spindle unit 1 further includes an air supply plate 4 and a cleaning air supply passage 5 for supplying cleaning air A1 to the tool mounting section 21. The air supply plate 4 is attached to the tip of the housing 3. The air supply plate 4 is formed in an annular shape and is located on the tip side Z1 of the housing 3, outside the radial direction R of the spindle cap portion 24 of the rotating spindle 2. The air supply plate 4 has an annular portion 41 located on the outer circumference of the tip of the rotating spindle 2, and a plurality of protrusions 42 that project outward in the radial direction R from a part of the circumferential direction S of the annular portion 41. In this embodiment, the protrusions 42 are formed to project from the left and right of an intermediate position in the Y-axis direction (vertical direction) of the annular portion 41.

[0023] As shown in Figures 2 to 4, an annular plate-side gap 40 is formed between the annular portion 41 of the air supply plate 4 and the outer circumference of the tip of the spindle cap portion 24 of the rotating spindle 2, allowing the rotating spindle 2 to rotate relative to the housing 3. The plate-side gap 40 is formed around the entire circumference of the central axis CL.

[0024] As shown in Figures 2, 3, and 5, the cleaning air supply passage 5 is formed from the housing 3 through the protrusion 42 of the air supply plate 4 to the spindle cap portion 24 of the rotating spindle 2. The cleaning air supply passage 5 is formed as the first to fourth supply passages 51, 52, 53, and 54. The first supply passage 51 is formed in the housing 3 parallel to the direction Z of the central axis CL of the rotating spindle 2. The second supply passage 52 is formed in the protrusion 42 of the air supply plate 4 so as to communicate with the first supply passage 51. The third supply passage 53 is formed annularly between the outer circumference of the tip of the spindle cap portion 24 of the rotating spindle 2 and the annular portion 41 so as to communicate with the second supply passage 52. The fourth supply passage 54 is formed in the spindle cap portion 24 of the rotating spindle 2 so as to communicate with the third supply passage 53 and is opened toward the tip side Z1 or the oblique tip side Z1 so as to blow cleaning air A1 out to the tool mounting portion 21.

[0025] The second supply passage 52 has a portion formed parallel to the direction Z of the central axis CL which communicates with the first supply passage 51, and a portion formed parallel to the radial direction R which communicates with the third supply passage 53. The third supply passage 53 is formed in such a way that it increases the width of the radial direction R of the plate-side gap 40 between the spindle cap portion 24 and the annular portion 41. The third supply passage 53 is formed in an annular shape so that the second supply passage 52 and the fourth supply passage 54 communicate regardless of the position S of the rotating spindle 2 relative to the housing 3 in the circumferential direction. The third supply passage 53 is formed by a combination of a recess formed by recessing on the outer circumferential surface of the spindle cap portion 24 and a recess formed by recessing on the inner circumferential surface of the annular portion 41. The third supply passage 53 may also be formed by only the recess formed by recessing on the outer circumferential surface of the spindle cap portion 24, or the recess formed by recessing on the inner circumferential surface of the annular portion 41.

[0026] The fourth supply passage 54 is formed at multiple locations in the circumferential direction S of the spindle cap portion 24 of the rotating spindle 2. The fourth supply passage 54 is formed by branching off from multiple locations in the circumferential direction S of the third supply passage 53. The fourth supply passage 54 has a radial portion 541 formed parallel to the radial direction R and communicating with the third supply passage 53, an axial portion 542 formed parallel to the central axis CL, and an opening portion 543 that opens from the portion formed parallel to the central axis CL toward the tip side Z1 or the oblique tip side Z1. The hole diameter of the opening portion 543 is smaller than the hole diameters of the radial portion 541 and the axial portion 542.

[0027] In this embodiment, the opening portion 543 of the fourth supply passage 54 branches out from the axial portion 542 and opens at the tip side Z1 of the mounting recess 211 and the contact tip surface 212. The opening portion 543 formed up to the mounting recess 211 opens toward the oblique tip side Z1, and the opening portion 543 formed up to the contact tip surface 212 opens toward the tip side Z1. The cleaning air A1 is then blown out from the tip side Z1 of the mounting recess 211 and the contact tip surface 212 toward the oblique tip side Z1 and the tip side Z1.

[0028] The opening 543 of the fourth supply passage 54 may be formed only at the tip side Z1 of the mounting recess 211. Alternatively, the opening 543 of the fourth supply passage 54 may be formed at an intermediate position or at the base end side Z2 in the direction Z of the central axis CL of the mounting recess 211.

[0029] As shown in Figures 2 and 4, the spindle unit 1 is further equipped with a coolant nozzle 7 that discharges coolant C toward the tool mounting section 21. The coolant C is used for lubrication, cooling, cleaning, etc. The coolant nozzle 7 is located on a part of the circumferential direction S at the tip of the housing 3. The protrusion 42 of the air supply plate 4 is located at a position in the circumferential direction S at the tip of the housing 3 that is different from the position in the circumferential direction S where the coolant nozzle 7 is located. This configuration allows the coolant nozzle 7 to be positioned as close as possible to the tool mounting section 21 of the rotating spindle 2 while avoiding interference with the protrusion 42 of the air supply plate 4.

[0030] The machine tool 10 in this embodiment is configured as a horizontal machining center, and the rotating spindle 2 is supported in the housing 3 by bearings 31 so as to be rotatable about a central axis CL along the horizontal direction. The coolant nozzle 7 is positioned above the annular portion 41 of the air supply plate 4 and is configured to discharge coolant C toward the central axis CL of the rotating spindle 2. At this time, a portion of the coolant C is discharged toward the outer circumferential surface of the annular portion 41. In other words, the coolant nozzle 7 in this embodiment is positioned at an upper position in the circumferential direction S (upper position in the Y-axis direction) at the tip of the housing 3 and is configured to discharge coolant C toward the downward direction. The protruding portion 42 of the air supply plate 4 is formed at left and right positions different from the upper position in the circumferential direction S where the coolant nozzle 7 is positioned.

[0031] The protrusions 42 are formed to protrude diagonally downward from the left and right sides of the annular portion 41 at an intermediate position in the Y-axis direction. The upper surface of the protrusions 42 is formed in a shape that slopes downward from the inside of the radial direction R connected to the annular portion 41 to the outside of the radial direction R. With this configuration, the coolant C discharged downward from the coolant nozzle 7 flows downward along the upper surfaces of the left and right protrusions 42. Therefore, even if foreign matter such as chips accumulates on the upper surface of the protrusions 42, this foreign matter can be discharged downward by the coolant C.

[0032] As shown in Figure 3, the outer circumferential surface of the spindle cap portion 24 of the rotating spindle 2 has a tip-side outer circumferential surface 242 that faces the inner circumferential surface of the annular portion 41 of the air supply plate 4, and a base-side outer circumferential surface 243 formed on the base end side Z2 in the direction Z of the central axis CL of the tip-side outer circumferential surface 242, and having a larger outer diameter than the tip-side outer circumferential surface 242. The base-side outer circumferential surface 243 is located on the tip end side Z1 in the direction Z of the central axis CL of the bearing 31 and is formed as the outer circumferential surface of the protruding portion 241 that protrudes the most outward in the radial direction R of the spindle cap portion 24. An annular recess 32 is formed on the inner circumferential surface of the tip portion of the housing 3, in which the protruding portion 241 of the spindle cap portion 24 is located.

[0033] The plate-side gap 40 is formed between the outer peripheral surface 242 on the tip side of the spindle cap portion 24 and the inner peripheral surface of the annular portion 41 of the air supply plate 4. Between the rotating spindle 2 and the housing 3, at a position Z1 on the tip side of the bearing 31, an annular housing-side gap 30 is formed that allows the rotating spindle 2 to rotate relative to the housing 3. The housing-side gap 30 is formed between the protruding portion 241 of the spindle cap portion 24 and the annular recess 32 of the housing 3, and between the tip side portion of the outer peripheral portion 23 of the spindle and the tip side portion of the housing 3.

[0034] As shown in Figures 2, 4, and 6, the housing 3 has an ingress prevention air supply passage 6 through which ingress prevention air A2 is supplied to protect the bearing 31 from coolant C. The ingress prevention air supply passage 6 has an axial portion 61 formed along the direction Z of the central axis CL of the housing 3, a radial portion 62 formed by bending inward from the axial portion 61 in the radial direction R, and an annular portion 63 formed in the circumferential direction S on the inside of the radial portion 62 in the radial direction R and communicating with the housing-side gap 30. The axial portion 61 and the radial portion 62 are formed at multiple locations in the circumferential direction S of the housing 3. The axial portion 61 and the radial portion 62 may be formed at only one location in the circumferential direction S of the housing 3. The width of the radial direction R of the annular portion 63 is greater than the width of the radial direction R of the housing-side gap 30.

[0035] The air supply passage 6 for preventing ingress is open to the tip side Z1 from between the spindle cap portion 24 of the rotating spindle 2 and the tip portion of the housing 3, so as to blow the air supply passage 6 for preventing ingress toward the tip side Z1. The air supply passage 6 is also open to the base end side Z2 toward the bearing 31 so as to allow the air supply passage 6 for preventing ingress toward the bearing 31 to flow into the bearing 31.

[0036] The ingress prevention air A2 supplied to the ingress prevention air supply passage 6 flows into the housing-side gap 30, preventing coolant C from entering the bearing 31. The ingress prevention air A2 flows from the axial portion 61 and radial portion 62 of the ingress prevention air supply passage 6 into the annular portion 63, and is blown out from the annular portion 63 to the tip side Z1 and base side Z2 in the direction Z of the central axis CL.

[0037] 3. Tool change operation of spindle unit 1 The tool holder 8 mounted on the tool mounting section 21 of the spindle unit 1 is replaced by an automatic tool changer. When replacing the tool holder 8 mounted on the tool mounting section 21, the tool holder 8 mounted on the tool mounting section 21 is removed by the change arm of the automatic tool changer. Next, coolant C is discharged from the coolant nozzle 7, cleaning air A1 is blown out from the cleaning air supply passage 5, and ingress prevention air A2 is blown out from the ingress prevention air supply passage 6. Then, another tool holder 8 is grasped by the change arm of the automatic tool changer, and the other tool holder 8 is mounted on the tool mounting section 21.

[0038] Because tool changes are performed at high speed, foreign matter such as chips is often ejected during machining before the tool change and is floating in the air during the tool change. During this tool change, the coolant C discharged from the coolant nozzle 7 is applied to the contact tip surface 212 of the tool mounting section 21 and the shaft portion 82 of another tool holder 8, preventing foreign matter such as chips from adhering to them. Also, during tool changes, cleaning air A1 is blown out from the opening 543 of the cleaning air supply passage 5, preventing foreign matter such as chips and coolant C from adhering to or entering the mounting recess 211 and contact tip surface 212 of the tool mounting section 21. Furthermore, during tool changes, ingress prevention air A2 is blown out from the ingress prevention air supply passage 6, preventing foreign matter such as chips and coolant C from entering the bearing 31.

[0039] 4. Effects In the spindle unit 1 of the machine tool 10 in this embodiment, a protrusion 42 is formed on the air supply plate 4 attached to the tip of the housing 3, and cleaning air A1 is blown out through the protrusion 42. Specifically, the cleaning air supply passage 5 for supplying cleaning air A1 to the tool mounting section 21 is formed as the first to fourth supply passages 51, 52, 53, and 54, extending from the housing 3 through the protrusion 42 to the tool mounting section 21 of the rotating spindle 2.

[0040] Furthermore, since the second supply passage 52 is formed on a protrusion 42 located in a part of the circumferential direction S of the annular portion 41 of the air supply plate 4, a space in the circumferential direction S can be formed in the remaining part of the circumferential direction S where the protrusion 42 is not located, outside the radial direction R of the annular portion 41. As a result, when replacing the tool holder 8 that is mounted on the tool mounting portion 21 of the spindle unit 1, even when the automatic tool changer approaches the tool mounting portion 21, interference between the spindle unit 1 and the automatic tool changer can be effectively avoided by utilizing the space in the circumferential direction S.

[0041] Therefore, with the spindle unit 1 of the machine tool 10 in this embodiment, interference between the spindle unit 1 and the automatic tool changer can be effectively avoided by using the air supply plate 4.

[0042] The present invention is not limited to these embodiments, and further different embodiments can be constructed without departing from the spirit of the invention. Furthermore, the present invention includes various modifications, modifications within the equivalent range, and so on. [Explanation of symbols]

[0043] 1 Spindle device 10 Machine tools 2 Rotating spindles 21 Tool mounting section 3 Housing 31 Bearings 4. Air supply plate 40 Plate-side gap 41 Ring section 42 Protrusion 5. Cleaning air supply path 6. Air supply channel for preventing ingress 7 Coolant nozzle 8 Tool holders

Claims

1. A spindle device of a machine tool, configured such that cleaning air is supplied to the tool mounting section where the tool holder is attached, The rotating main shaft on which the tool mounting portion is formed, A housing that rotatably supports the aforementioned rotating main shaft by bearings, An air supply plate is attached to the tip of the housing and forms an annular plate-side gap between itself and the outer circumference of the tip of the rotating spindle, allowing the rotating spindle to rotate. It includes a cleaning air supply passage for supplying the cleaning air to the tool mounting section, The aforementioned air supply plate is An annular portion arranged on the outer circumference of the tip of the main rotating shaft, The annular portion has one or more protrusions that project radially outward from a part of its circumferential direction, The aforementioned cleaning air supply path is A first supply channel formed in the housing, A second supply passage formed in the protruding portion so as to communicate with the first supply passage, A third supply passage is formed in an annular shape between the outer circumference of the tip of the rotating main shaft and the annular portion so as to communicate with the second supply passage, A spindle device for a machine tool, comprising: a fourth supply passage formed at the tip of the rotating spindle so as to communicate with the third supply passage, and for blowing the cleaning air out to the tool mounting section.

2. Between the rotating spindle and the housing, at a position closer to the tip than the bearing, an annular housing-side gap is formed that allows the rotating spindle to rotate relative to the housing. The spindle device of a machine tool according to claim 1, wherein the housing has an intrusion prevention air supply passage formed therein, which supplies intrusion prevention air that flows into the gap on the housing side to prevent coolant from entering the bearing.

3. The spindle device of a machine tool according to claim 2, wherein the air supply passage for preventing ingress is open from between the rotating spindle and the housing toward the tip side so as to blow out the air for preventing ingress.

4. The tool mounting portion is formed recessed from the tip surface of the rotating spindle and has a mounting recess into which the shaft portion of the tool holder is inserted. The spindle device of a machine tool according to any one of claims 1 to 3, wherein the fourth supply passage is formed by branching to multiple locations in the circumferential direction of the rotating spindle and opens into the mounting recess.

5. The tool mounting portion has a contact tip surface that contacts the end face of the flange portion of the tool holder, The spindle device of a machine tool according to claim 4, wherein the fourth supply passage also opens to the contact tip surface.

6. The housing further comprises a coolant nozzle that is positioned in a circumferential part of the tip of the housing and discharges coolant, The spindle device of a machine tool according to any one of claims 1 to 3, wherein the protruding portion is located at a circumferential position on the tip of the housing that is different from the circumferential position on which the coolant nozzle is located.

7. The rotating main shaft is supported in the housing by the bearing so as to be rotatable about a rotation axis along the horizontal direction, The coolant nozzle is positioned above the annular portion and is configured to discharge a portion of the coolant toward the annular portion. The spindle device for a machine tool according to claim 6, wherein the upper surface of the protruding portion is formed in a shape that slopes downward from a radially inward position connected to the annular portion toward the radially outward direction.

8. A machine tool equipped with a spindle device according to any one of claims 1 to 3.

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