Ultrasonic Air Bearing Spindle Device

Abstract

The present invention relates to an ultrasonic spindle device, and provides an ultrasonic air bearing spindle device including: a housing having an internal space; a hollow shaft rotatably provided within the housing; a hollow ultrasonic generator provided within the hollow shaft and capable of generating ultrasonic waves when supplied with power; a tool horn provided at the front end of the shaft and coupled to the ultrasonic generator; a carbon brush that receives power from an external source and is in electrical contact with a conductive slip ring at the rear end of the shaft; wires that electrically connect the slip ring and the ultrasonic generator; and a flow path formed within the housing and communicating with the outside, the flow path including: a first supply flow path that guides outside air into the housing through the rear end of the housing; a dust exhaust flow path that branches off from the first supply flow path and guides the outside air toward the carbon brush; and a cooling flow path that branches off from the first supply flow path and guides the outside air toward the ultrasonic generator.

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic spindle device, and more particularly to an ultrasonic spindle device that is equipped with an air bearing and is capable of cooling and dust discharge. [Background technology]

[0002] An ultrasonic machining device that uses ultrasonic vibrations is a device that uses ultrasonic vibrations to grind, cut, and otherwise process hard and brittle materials, and is generally used with an ultrasonic spindle device attached so that the cutting tool can be rotated and vibrated to perform machining.

[0003] Such ultrasonic processing equipment is used in the processing of hard-to-cut materials that are difficult to process and grind due to their high strength and brittleness, such as silicon carbide (SiC), porous ceramics, tempered glass for mobile phone touch panels, sapphire, and quartz, and the demand for ultrasonic processing equipment is gradually increasing.

[0004] Ultrasonic spindles mainly use an ultrasonic generator and a vibrator to generate ultrasonic vibrations. The ultrasonic generator supplies electrical energy to the vibrator installed inside the ultrasonic spindle, which then generates ultrasonic vibrations and transmits them to the cutting tool located at the front end of the ultrasonic spindle. The cutting tool rotates and vibrates ultrasonically while coming into contact with the workpiece to machine it. To generate rotational force, ultrasonic spindles use a stator fixed inside and a rotor fixed to the shaft.

[0005] Recently, ultrasonic spindles capable of high-speed rotation have become necessary for ultra-precision machining of difficult-to-cut materials, and ultrasonic air bearing spindles, which use air bearings to levitate the shaft, have been introduced. Such ultrasonic air bearing spindles generally use carbon brushes connected to an external power source to transmit power to the vibrator, and slip rings that electrically contact the carbon brushes. In this case, dust is generated as the carbon brushes wear, and the generated dust accumulates around the rotating shaft, causing malfunction and failure of the spindle.

[0006] Furthermore, heat generated by the vibrator is transferred to surrounding parts, causing material changes and expansion, which can lead to separation from the central rotating shaft, shortening the lifespan and hindering machining precision. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent No. 10-1904799 Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION In one embodiment, the present invention provides an ultrasonic air bearing spindle device that can discharge dust caused by wear of the carbon brush and cool the spindle whose temperature has risen due to heat generated by the vibrator. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the present invention provides a housing having a space formed therein, and a cooling passage formed inside the housing and communicating with the outside, the passage including: a first supply passage that guides outside air into the housing through the rear end of the housing; a dust exhaust passage that branches off from the first supply passage and guides the outside air toward the carbon brush; and a cooling passage that branches off from the first supply passage and guides the outside air toward the ultrasonic generator.

[0010] The dust discharge passage may include a first dust discharge passage that guides outside air to surround the rear end of the shaft, and a second dust discharge passage that guides the outside air in the first dust discharge passage to the outside of the housing.

[0011] The cooling passage may include a first inner cooling passage that penetrates the interior of the shaft in the longitudinal direction, and a second inner cooling passage that guides the outside air of the first inner cooling passage to surround the outer surface of the ultrasonic generating portion.

[0012] The tool may further include a fastening pin including a pin body that penetrates the ultrasonic generator and is connected to the tool horn, and a pin head that is provided on the pin body and has a cross-sectional area larger than that of the pin body, and a pin head whose outer surface is connected to the inside of the first inner cooling channel, and the cooling channel may further include a connecting cooling channel that communicates the first inner cooling channel with the second inner cooling channel and guides outside air of the first inner cooling channel to pass sequentially through the pin head and the ultrasonic generator.

[0013] The cooling passage may further include an outer cooling passage that guides the outside air of the second inner cooling passage radially outward from the front end of the shaft portion to cool the housing.

[0014] The housing may further include an air bearing portion that rotatably supports the shaft portion, and the flow path may further include a second supply flow path that guides outside air to the edge of the housing via the rear end of the housing, a housing cooling flow path that branches off from the second supply flow path and guides outside air along the edge of the housing to the front end of the housing, and a bearing supply flow path that branches off from the housing cooling flow path and guides outside air to the air bearing portion.

[0015] The rotor may further include a drive unit including a stator provided inside the housing and a rotor coupled to the outside of the shaft and acting on the stator to rotate the shaft, the air bearing unit may further include a front radial bearing unit that supports a front end of the shaft for radial rotation and a rear radial bearing unit that supports a rear end of the shaft for radial rotation, and the bearing supply passage may further include a first bearing passage supplied to the rear radial bearing unit, a second bearing passage supplied to the front radial bearing unit, and a connecting bearing passage that communicates with the first bearing passage and the second bearing passage, respectively, and guides outside air from the first bearing passage between the stator and the rotor.

[0016] The air bearing portion may further include a front thrust bearing portion that supports the front end of the shaft portion so that it can rotate freely in the axial direction, and the bearing supply passage may further include a third bearing passage that guides outside air from the second bearing passage to the front thrust bearing portion.

[0017] The air bearing portion may further include a rear thrust bearing portion that supports the rear end of the shaft portion so that it can rotate freely in the axial direction, and the bearing supply passage may further include a third bearing passage that guides outside air from the first bearing passage to the rear thrust bearing portion.

[0018] The flow path further includes a front-end exhaust flow path that exhausts the outside air inside the housing to the outside through the outer surface of the tool horn, and a portion of the outside air flowing into the housing through the first supply flow path and the second supply flow path can be exhausted to the outside through the front-end exhaust flow path. [Effects of the Invention]

[0019] As described above, the embodiment of the present invention provides the effects of discharging dust caused by wear of the carbon brush and cooling the spindle whose temperature has risen due to heat generated by the vibrator. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing an ultrasonic air bearing spindle device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view showing the ultrasonic air bearing spindle device shown in FIG. [Figure 3] FIG. 2 is a diagram showing a first supply flow path and flow paths branching from the first supply flow path of the ultrasonic air bearing spindle device. [Figure 4] FIG. 2 is a diagram showing a first supply flow path and flow paths branching from the first supply flow path of the ultrasonic air bearing spindle device. [Figure 5] 10A and 10B are diagrams illustrating the structure of a fastening pin for explaining a connecting cooling channel. [Figure 6] FIG. 2 is a diagram showing a second supply flow path of an ultrasonic air bearing spindle device and flow paths branching therefrom. DETAILED DESCRIPTION OF THE INVENTION

[0021] The embodiments described below are illustrative to aid in understanding the invention, and it should be understood that the present invention can be implemented in various forms different from the embodiments described herein. However, when describing the present invention, if it is determined that specific descriptions of related known functions and components may unnecessarily obscure the gist of the present invention, detailed descriptions and specific illustrations thereof will be omitted. In addition, the accompanying drawings may not be drawn to scale to aid in understanding the invention, and the dimensions of some components may be exaggerated.

[0022] The terms "first" and "second" used in this application are used to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one structural element from another.

[0023] Furthermore, the terms used in this application are merely used to describe specific embodiments and are not intended to limit the scope of the present invention. A singular expression includes a plural expression unless the context clearly dictates otherwise. In this application, terms such as "comprises," "consists," or "has" specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0024] An ultrasonic air bearing spindle device according to an embodiment of the present invention will now be described with reference to Figures 1 and 2. Figure 1 is a perspective view showing an ultrasonic air bearing spindle device according to an embodiment of the present invention, and Figure 2 is a cross-sectional view showing the ultrasonic air bearing spindle device shown in Figure 1.

[0025] 1 and 2, an ultrasonic air bearing spindle device 1 according to one embodiment of the present invention includes a housing 100 having a space formed therein, shaft portions 310, 320, 330 that are provided inside the housing 100 and rotate, a hollow ultrasonic generator 40 that generates ultrasonic waves, a tool horn 71 that is coupled to the ultrasonic generator 40, a carbon brush 41 that receives external power, a wire (not shown) that electrically connects the slip ring 50 and the ultrasonic generator 20, and a flow path that guides outside air into the housing 100.

[0026] The housing 100 is elongated in one direction and has an internal space. The housing 100 includes main bodies 131, 132, 110, and 120, a front cover 140 connected to the front ends of the main bodies 131, 132, 110, and 120, and a rear cover 150 connected to the rear ends of the main bodies 131, 132, 110, and 120.

[0027] The main body parts 131, 132, 110, 120 are formed to extend long in one direction and include a middle main body 110, a rear main body 120 connected to the rear end of the middle main body 110, a second front main body 132 connected to the front end of the middle main body 110, and a first front main body 131 connected to the front surface of the second front main body 132.

[0028] The middle body 110 is formed in a hollow cylindrical shape and has an inner circumferential surface and an outer circumferential surface.

[0029] The rear body 120 has a space formed therein that communicates with the hollow space of the middle body 110 .

[0030] First front body 131 is formed in a hollow ring shape. A horn support part 75 (described later) is provided in the hollow of first front body 131 and is rotatably supported by first front body 131. Horn support part 75 rotates together with tool horn 71.

[0031] The second front body 132 is connected to the rear surface of the first front body 131 and is formed in a hollow ring shape. The second front body 132 sandwiches the front radial bearing unit 210 between itself and the middle body 110, and supports the front radial bearing unit 210 together with the middle body 110. More specifically, the second front body 132 supports the front flange 211 of the front radial bearing unit 210 together with the middle body 110.

[0032] The front cover 140 is coupled to the front of the second front body 132, and has a hole formed in the center thereof through which the tool horn 71 (described later) passes. The inner circumferential surface of the hole in the front cover 140 and the outer circumferential surface of the tool horn 71 are spaced apart from each other to form a front end discharge port 141.

[0033] The rear cover 150 is coupled to the rear surface of the rear body 120 and has a first supply port 151 and a second supply port 152 formed therethrough to introduce outside air into the housing 100 and guide it therethrough.

[0034] The shaft portions 310 , 320 , 330 include a front shaft 320 , a rear shaft 310 , and a conductive shaft 330 .

[0035] The rear shaft 310 is elongated in one direction and has a space therein that can function as a flow passage, and a wire is accommodated between the inner and outer circumferential surfaces.

[0036] A rotor 11 is provided on the outer circumferential surface of the rear shaft 310. The rotor 11, together with the stator 12, constitutes an induction motor of an AC motor. In addition, a pair of rotor supports 311 and 312 are provided on the outer circumferential surface of the rear shaft 310 to support the rotor 11 at its front and rear ends.

[0037] The front shaft 320 extends in one direction and is connected to the front end of the rear shaft 310. The front shaft 320 has an internal space that communicates with the internal space of the rear shaft 310. The front shaft 320 has a shaft flange 230 at its front end, the shaft flange 230 having an outer diameter larger than that of the front shaft 320.

[0038] At least the rear and front surfaces of the shaft flange 230 are enveloped by the outside air discharged forward from the front radial bearing portion 210 , thereby forming a thrust bearing portion 231 .

[0039] The conductive shaft 330 extends in one direction and is connected to the rear end of the rear shaft 310. A space is formed inside the conductive shaft 330, which is in communication with the interior space of the rear shaft 310. The conductive shaft 330 is surrounded by a conductive slip ring 50, so that the outer circumferential surface of the conductive shaft 330 contacts the inner circumferential surface of the slip ring 50.

[0040] The ultrasonic generator 20 receives electrical energy from an external ultrasonic oscillator to generate ultrasonic waves, and may be, for example, a hollow piezoelectric element, and is connected to the rear end of the tool horn 71 via a fastening pin 30.

[0041] 3, the fastening pin 30 includes a pin body 31 that is inserted into the tool horn 71 and a pin head 32 that is attached to the pin body 31 and has a cross-sectional area larger than that of the pin body 31. A portion of the outer circumferential surface of the pin head 32 is coupled to a portion of the inner surface of the internal space of the rear shaft 310, thereby connecting the ultrasonic generator and the rear shaft 310.

[0042] The tool horn 71 is connected to the ultrasonic generator 20, and its front end protrudes through the first front body 131, the second front body 132, and the front cover 140, and its rear end is accommodated in the front shaft 320. A collet 72 and a collet nut 73 are provided at the front end of the tool horn 71, so that a tool 74 can be connected thereto.

[0043] Meanwhile, a power supply unit 40 is provided penetrating the side of the rear body 120. The power supply unit 40 serves to supply external power to the slip ring 50 and includes a carbon brush 41 and a brush housing 42 that accommodates and supports the carbon brush 41.

[0044] The carbon brush 41 may be elastically supported by an elastic body so as to contact the slip ring 50 with a constant pressure. The slip ring 50 is electrically connected to the ultrasonic generator 20 via a wire.

[0045] The rotor 11 and stator 12 described above form the driving unit 10 that generates power to rotate the shaft, with the rotor 11 being connected to the outer circumferential surface of the rear shaft 310 and the stator 12 being connected to the inner circumferential surface of the middle body 110.

[0046] The ultrasonic air bearing spindle device 1 according to the embodiment of the present invention further includes air bearing portions that rotatably support the shaft portions 310, 320, and 330.

[0047] The air bearings allow outside air to flow in to support the shafts rotatably, and function to minimize friction that occurs during rotation by lifting the shafts 310, 320, and 330. The air bearings include radial bearings 210 and 220 that support the shafts in the radial direction, and a thrust bearing 231 that supports the shafts in the axial direction.

[0048] The radial bearing portions 210, 220 include a front radial bearing portion 210 that rotatably supports a front shaft 320, and a rear radial bearing portion 220 that rotatably supports the rear end portion of the rear shaft 310.

[0049] The front radial bearing unit 210 has a space formed therein to accommodate the front shaft 320, and has a flow path and a nozzle connected to the flow path formed therein to forcefully discharge outside air toward the outer circumferential surface of the front shaft 320 to lift it up. The front radial bearing unit 210 has a front flange 211 at its front end, the front flange 211 having an outer diameter larger than that of its rear end.

[0050] The rear radial bearing unit 220 has a space formed therein to accommodate the rear end of the rear shaft 310, and has a flow path and a nozzle connected to the flow path formed therein to forcefully discharge outside air toward the outer circumferential surface of the rear shaft 310 to lift it up. The rear radial bearing unit 220 has a rear flange 221 at its rear end that has an outer diameter larger than that of its front end.

[0051] When the outside air moves toward the front radial bearing part 210 and the rear radial bearing part 220 from the flow paths formed on the outer and inner surfaces of the middle body 110, the front radial bearing part 210 and the rear radial bearing part 220 respectively receive the outside air through the multiple outer circumferential grooves 212, 222 surrounding the outer circumferential surface and then direct the air into the multiple flow paths formed radially inside.

[0052] The thrust bearing portion 231 includes a front thrust bearing portion 232 that rotatably supports the front surface of the shaft flange 230, and a rear thrust bearing portion 233 that rotatably supports the rear surface of the shaft flange 230.

[0053] The rear thrust bearing portion 233 is formed by separating the rear surface of the shaft flange 230 from a part of the front surface of the front radial bearing portion 210 when outside air is discharged forward from the front radial bearing portion 210 .

[0054] The front thrust bearing part 232 is formed when the outside air that collides with the rear surface of the shaft flange 230 moves to the front surface of the shaft flange 230 and separates the front surface of the shaft flange 230 from the rear surface of the first front body 131. Meanwhile, the first supply port 151 of the rear cover 150 is provided with an air dispenser 60 that distributes the outside air that flows into the first supply port 151.

[0055] The air dispenser 60 has two branched flow paths formed inside, one of which is connected to the inside of the conductive shaft 330, and the other is connected to the space between the slip ring 50 and the rear body 120.

[0056] The flow paths formed inside the housing 100 of the ultrasonic air bearing spindle device 1 according to one embodiment of the present invention and communicating with the outside will be described with reference to Figures 4 to 6. Figures 4 and 5 show the first supply flow path R110 of the ultrasonic air bearing spindle device 1 and the flow paths branching off from it, and Figure 6 shows the second supply flow path R210 of the ultrasonic air bearing spindle device 1 and the flow paths branching off from it.

[0057] 4 to 6, the flow passages include a first supply flow passage R110, a dust discharge flow passage R120 branching off from the first supply flow passage R110, and cooling flow passages R130, R140, R150, and R160.

[0058] The first supply flow path R110 guides the outside air to the outside of the air dispenser 60 through the first supply port 151.

[0059] The dust discharge passage R120 includes a first dust discharge passage R121 that guides outside air so as to surround the rear end of the shaft, and a second dust discharge passage R122 that guides the outside air of the first dust discharge passage R121 to the outside of the housing 100.

[0060] The first dust discharge passage R121 guides the outside air guided into the air dispenser 60 to the space formed between the slip ring 50 and the conductive shaft 330.

[0061] The second dust discharge passage R122 discharges the outside air from the first dust discharge passage R121 via a rear discharge pipe 127 formed to penetrate the rear main body 120 on the radially outer side.

[0062] During this process, dust generated from the carbon brush 41 that comes into contact with the slip ring 50 and wears down is discharged to the outside.

[0063] In addition, the dust discharge passage R120 contacts the entire area of ​​the slip ring 50 excluding the area in contact with the slip ring 50 and the carbon brush 41, thereby effectively discharging dust and also generating a cooling effect for the slip ring 50. Meanwhile, the dust discharge passage R120 discharges outside air that is supplied from the rear radial bearing unit 220 and passes between the rear surface of the rotor support unit 311 and the front surface of the rear body 120 to the outside. The cooling passages R130, R140, R150, R160 include a first inner cooling passage R130, a second inner cooling passage R150, a connecting cooling passage R140, and an outer cooling passage R160.

[0064] The first inner cooling flow path R130 guides the outside air guided into the air dispenser 60 to pass through the inside of the rear shaft 310 in the longitudinal direction. In this process, the center of the housing 100 and the inner circumferential surface of the drive unit 10 are effectively cooled.

[0065] The connecting cooling passage R140 connects the first inner cooling passage R130 and the second inner cooling passage R150, and guides the outside air of the first inner cooling passage R130 so that it flows around the pin head 32 and the rear end of the ultrasonic generator 20.

[0066] The second inner cooling passage R150 guides the connecting cooling passage R140 and the outside air so as to surround the outer circumferential surface of the ultrasonic generating part 20.

[0067] As the outside air flows along the connecting cooling passage R140 and the second inner cooling passage R150, it can cool down the heat generated from the ultrasonic generator 20 that has been transferred to the pin head 32 and the heat that still remains in the ultrasonic generator 20.

[0068] The outer cooling passage R160 guides the outside air from the second inner cooling passage R150 radially outward of the front shaft 320 (310, 320, 330), then guides it to pass forward through the second front body 132, then guides it to pass radially inward through the first front body 131, and finally guides it to be discharged through the front end exhaust port 141. In this process, the front end of the housing 100 can be cooled.

[0069] On the other hand, the flow paths include a second supply flow path R210, a housing cooling flow path R220, and bearing supply flow paths R231, R232, and R233.

[0070] The second supply flow path R210 guides the outside air introduced through the second supply port 152 to the outside in the radial direction of the rear cover 150, and then guides the outside air to move forward.

[0071] The housing cooling passage R220 extends in the first direction and passes between the outer and inner peripheral surfaces of the middle body 110. The housing cooling passage R220 guides the outside air to the second supply passage R210 forward along the edges of the rear body 120, rear flange 221, middle body 110, front flange 211, and shaft flange 230. In this process, part of the peripheral edge of the housing 100 and the outer peripheral surface of the drive unit 10 are effectively cooled.

[0072] Meanwhile, a coolant flow path R220a through which coolant flows is additionally provided between the outer and inner circumferential surfaces of the middle body 110. By providing the coolant flow path R220a, the housing 100 can be cooled not only by the outside air but also by the coolant, and other components other than the housing 100 can also be cooled.

[0073] The bearing supply passages R231, R232, and R233 branch off from the housing cooling passage R220 and guide the outside air from the housing cooling passage R220 to the air bearing unit. The bearing supply passages R231, R232, and R233 include radial passages R231 and R232 that supply outside air to the radial bearing units 210 and 220, and a thrust passage R233 that supplies outside air to the thrust bearing unit 231.

[0074] The radial flow paths R231 and R232 include a front radial flow path R232 that supplies the outside air of the housing cooling flow path R220 to the front radial bearing portion 210 and a rear radial flow path R231 that supplies the outside air to the rear radial bearing portion 220, respectively.

[0075] The thrust flow passage R233 guides the outside air from the front radial flow passage R232 through the rear surface, side surface, front surface, etc. of the shaft flange 230 as described above.

[0076] On the other hand, the bearing supply passages R231, R232, and R233 further include a connecting bearing passage R235 that connects the front radial passage R232 and the rear radial passage R231.

[0077] The connecting bearing passage guides the outside air from the rear radial passage R231 to the gap between the stator 12 and the rotor 11, and then guides it to the front radial passage R232. In this process, the center of the drive unit 10 is cooled.

[0078] On the other hand, the housing cooling passage R220 and the thrust passage R233 are formed in the first front body 131 and are connected to a front body passage R240 formed extending radially inward, and the front body passage R240 is connected to a front end discharge passage R300 formed between the inner surface of the front cover 140 and the outer surface of the tool horn 71.

[0079] As described above, the present invention has been described using limited examples and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary skill in the art to which the present invention pertains within the technical spirit of the present invention and the equivalent scope of the claims set forth below. [Explanation of symbols]

[0080] 1: Ultrasonic air bearing spindle device 10: Drive unit 20: Ultrasonic wave generator 40: Electrode supply section 71: Tool horn 100: Housing 131, 132, 110, 120: Main body 140: Front cover 150: Rear cover 210, 220: Radial bearing section 231: Thrust bearing part 310, 320, 330: Shaft section

Claims

1. a housing having a space formed therein; a hollow shaft portion rotatably provided inside the housing; a hollow ultrasonic generating unit provided in the hollow of the shaft portion and configured to generate ultrasonic waves when supplied with power; a tool horn provided at a front end of the shaft portion and coupled to the ultrasonic generator; a carbon brush that is supplied with power from an external source and is in electrical contact with a conductive slip ring at the rear end of the shaft portion; a wire electrically connecting the slip ring and the ultrasonic generator; a flow path formed inside the housing and communicating with the outside, The flow path is a first supply flow path that guides outside air into the housing through a rear end of the housing; a dust discharge flow path branching from the first supply flow path and guiding outside air to the carbon brush side; a cooling flow path that branches off from the first supply flow path and guides outside air toward the ultrasonic generating unit.

2. The dust discharge flow path is a first dust exhaust passage that guides outside air so as to surround the rear end of the shaft; 2. The ultrasonic air bearing spindle device according to claim 1, further comprising: a second dust exhaust passage that guides outside air from the first dust exhaust passage to the outside of the housing.

3. The cooling channel comprises: a first inner cooling passage extending longitudinally through the interior of the shaft; 2. The ultrasonic air bearing spindle device according to claim 1, further comprising: a second inner cooling passage that guides the outside air of the first inner cooling passage so as to surround the outer circumferential surface of the ultrasonic generating portion.

4. a fastening pin including a pin body that penetrates the ultrasonic generating portion and is coupled to the tool horn; and a pin head that is provided on the pin body and has a cross-sectional area larger than a cross-sectional area of ​​the pin body, and a pin head having an outer surface that is coupled to an inside of the first inner cooling channel, The cooling channel comprises:

4. The ultrasonic air bearing spindle device of claim 3, further comprising a connecting cooling passage that connects the first inner cooling passage and the second inner cooling passage and guides the outside air of the first inner cooling passage to pass sequentially through the pin head and the ultrasonic generator.

5. The cooling channel comprises:

5. The ultrasonic air bearing spindle device according to claim 4, further comprising an outer cooling passage that guides the outside air of the second inner cooling passage radially outward of the front end of the shaft portion to cool the housing.

6. further including an air bearing portion that rotatably supports the shaft portion; The flow path is a second supply flow path that guides outside air to an edge of the housing through a rear end of the housing; a housing cooling flow path that branches off from the second supply flow path and guides the outside air along an edge of the housing to a front end of the housing; 2. The ultrasonic air bearing spindle device according to claim 1, further comprising a bearing supply passage branching from the housing cooling passage and guiding outside air to the air bearing portion.

7. a driving unit including a stator provided inside the housing and a rotor coupled to the outside of the shaft unit and acting on the stator to rotate the shaft, The air bearing portion is a front radial bearing portion that supports a front end portion of the shaft portion so as to be rotatable in the radial direction, and a rear radial bearing portion that supports a rear end portion of the shaft portion so as to be rotatable in the radial direction, The bearing supply channel includes: a first bearing flow passage supplied to the rear radial bearing portion; a second bearing flow passage supplied to the front radial bearing portion; 7. The ultrasonic air bearing spindle device of claim 6, further comprising a connecting bearing passage that communicates with the first bearing passage and the second bearing passage, respectively, and guides the outside air of the first bearing passage between the stator and the rotor.

8. The air bearing portion is a thrust bearing portion that supports a front end portion of the shaft portion so as to be rotatable in the axial direction; The bearing supply channel includes:

8. The ultrasonic air bearing spindle device according to claim 7, further comprising a third bearing passage for guiding the outside air of the second bearing passage to the thrust bearing portion.

9. a shaft flange having an outer diameter larger than the outer diameter of the shaft portion is provided at a front end of the shaft portion; The thrust bearing portion is a front thrust bearing portion that supports a front surface of the shaft flange so as to be rotatable in the axial direction; 9. The ultrasonic air bearing spindle device according to claim 8, further comprising a rear thrust bearing portion that supports the rear surface of the shaft flange so as to be rotatable in the axial direction.

10. The flow path is a front-end exhaust flow path that exhausts outside air from inside the housing to the outside through an outer circumferential surface of the tool horn; 7. The ultrasonic air bearing spindle device according to claim 6, wherein a portion of the outside air flowing into the housing through the first supply passage and the second supply passage is discharged to the outside through the front-end discharge passage.

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