Air floating spindle and circuit board processing equipment

Abstract

This application belongs to the field of circuit board processing technology, and provides an air-bearing spindle and circuit board processing equipment. The air-bearing spindle includes a spindle core, a first thrust bearing, and a second thrust bearing. A rotor disk is disposed on the spindle core. The first and second thrust bearings are located on opposite sides of the rotor disk along the axial direction. Air film gaps are formed between the first thrust bearing and the rotor disk, and between the second thrust bearing and the rotor disk. The first and / or second thrust bearings are provided with a resonant cavity, which includes a cavity body and a necked section. One end of the necked section is connected to the cavity body, and the other end is connected to the corresponding air film gap. The cross-sectional area of ​​the necked section is smaller than that of the cavity body. This application can achieve frequency locking by utilizing the Helmholtz resonance effect of the resonant cavity, causing the gas pressure in the air film gap to change periodically, thereby driving the rotor disk to drive the spindle core to generate high-frequency reciprocating motion along the axial direction, realizing vibration processing of the machining tool, which is beneficial to improving processing quality and efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of circuit board processing, and more particularly to an air floating spindle and a circuit board processing device. BACKGROUND

[0002] With the wide application of artificial intelligence technology, and the continuous maturity of the fifth generation mobile communication technology and the sixth generation mobile communication technology, printed circuit boards are rapidly evolving towards more layers, thicker substrates and higher precision. Especially under the impetus of the increasing miniaturization and high integration of electronic devices, the circuit density is significantly improved, and the thickness of the circuit board is correspondingly increased, so the technical requirements for the circuit board manufacturing process, especially the circuit board micro-hole processing technology, are also greatly improved.

[0003] During the micro-hole processing of the traditional air floating spindle on a relatively thick circuit board, phenomena such as processing tool jamming and sharp rise in cutting temperature are prone to occur, which in turn leads to shortening of the service life of the processing tool or even breakage, seriously affecting the processing quality and efficiency. SUMMARY

[0004] In order to overcome the problems existing in the prior art, the main purpose of the present application is to provide an air floating spindle and a circuit board processing device.

[0005] In order to achieve the above-mentioned purpose, the following technical solutions are specifically adopted in the present application: According to a first aspect of the embodiments of the present application, an air floating spindle is provided, comprising a shaft core, a first thrust bearing and a second thrust bearing, a rotor disc is arranged on the shaft core, the first thrust bearing and the second thrust bearing are respectively located on the two sides of the rotor disc along the axial direction; a gas film gap is formed between the first thrust bearing and the rotor disc and between the second thrust bearing and the rotor disc; the first thrust bearing and the second thrust bearing are each provided with a gas supply throttling structure for supplying gas to the corresponding gas film gap; the first thrust bearing and / or the second thrust bearing is provided with a resonance cavity, the resonance cavity comprises a cavity body and a necked section, one end of the necked section communicates with the cavity body, and the other end communicates with the corresponding gas film gap, the cross-sectional area of the necked section is smaller than that of the cavity body; the air floating spindle further comprises a shell, the shaft core is rotatably arranged in the shell, the rotor disc, the first thrust bearing and the second thrust bearing are arranged in the shell, the shell is provided with a gas supply channel, and the gas supply channel communicates with each gas supply throttling structure; The resonance cavity can be configured to generate a Helmholtz resonance under the action of gas to form a periodic pressure pulsation, the periodic pressure pulsation is output to the corresponding gas film gap through the necked section, the gas pressure in the gas film gap changes periodically to drive the rotor disc to drive the shaft core to reciprocate along the axial direction.

[0006] Optionally, the necked section is coaxially arranged with the cavity.

[0007] Optionally, the necked section is a single through-hole or a micro-hole array; wherein, when the necked section is a micro-hole array, the micro-hole array comprises a plurality of spaced-apart through-holes, each of which is in communication with the cavity and the gas film gap at two ends thereof.

[0008] Optionally, the gas supply throttling structure comprises a gas supply throttling hole having an inlet end and an outlet end, the inlet end being in communication with the gas supply channel, and the outlet end being in communication with the corresponding cavity.

[0009] Optionally, the gas supply throttling structure comprises a gas supply throttling hole having an inlet end and an outlet end, the inlet end being in communication with the gas supply channel, and the outlet end being in communication with the corresponding gas film gap and being arranged adjacent to the necked section.

[0010] Optionally, the first and / or second thrust bearing comprises a bearing body and a porous material structure, the porous material structure being arranged on an end surface of the bearing body facing the rotor disc, the porous material structure having a plurality of micro-holes inside, and the resonant cavity being arranged on the bearing body and / or the porous material structure.

[0011] Optionally, the porous material structure extends in an axial direction to have a ring shape and covers at least a partial area of the end surface of the bearing body facing the rotor disc; or the porous material structure comprises a plurality of arc-shaped sections distributed in a circumferential direction.

[0012] Optionally, the micro-holes of the porous material structure constitute at least a part of the gas supply throttling structure, and the micro-holes are used for supplying gas to the gas film gap.

[0013] Optionally, the gas supply throttling structure comprises a gas supply throttling hole arranged through the porous material structure, the gas supply throttling hole having a hole diameter greater than that of the micro-holes, and the gas supply throttling hole and the micro-holes are used for simultaneously supplying gas to the gas film gap.

[0014] Optionally, the resonant cavity is arranged on the porous material structure, and the cavity is in communication with at least one gas supply throttling hole and at least one micro-hole.

[0015] Optionally, the resonant frequency f of the resonant cavity satisfies the following relationship:

[0016] Wherein, c is the speed of sound, A is the cross-sectional area of the neck section, V is the volume of the cavity, L is the axial length of the neck section; by setting at least one of A, V and L, the resonance frequency of the resonance cavity is matched with the frequency of the axial reciprocating movement of the shaft core.

[0017] According to a second aspect of the embodiments of the present application, a circuit board processing equipment is provided, comprising the air floating spindle as described in any one of the above.

[0018] The air floating spindle and the circuit board processing equipment provided by the present application have the following beneficial effects: compared with the prior art, the air floating spindle of the present application sets a resonance cavity comprising a cavity and a neck section on the first thrust bearing and / or the second thrust bearing, uses the Helmholtz resonance effect of the resonance cavity to realize frequency locking, generates stable periodic pressure pulsation under the action of gas, the periodic pressure pulsation is output to the gas film gap through the neck section, the gas pressure in the gas film gap changes periodically, thereby driving the rotor disc to produce high-frequency reciprocating movement along the axial direction, and then driving the processing tool at the end of the shaft core to produce axial high-frequency vibration. In this way, when processing thicker and harder circuit boards, the processing tool synchronously vibrates during the cutting process, which can convert continuous cutting into intermittent pecking cutting, so that the cuttings are periodically broken into small pieces and are easy to discharge, and the tool is separated from the contact with the hole bottom material at the vibration separation moment, the cutting temperature is periodically relieved, the axial average cutting force is significantly reduced, and problems such as processing tool jamming and sharp rise in cutting temperature are effectively avoided, which is beneficial to prolong the service life of the processing tool and reduce the tool breakage rate, thereby being beneficial to improve the processing quality and efficiency, and meeting the processing process requirements of the continuously thickening circuit board micro-holes. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 The axial sectional structure schematic diagram of the air floating spindle provided by an embodiment of the present application; Figure 2 The enlarged view of A in Figure 1 ; Figure 3 The axial sectional structure schematic diagram of the second thrust bearing provided by an embodiment of the present application Figure 1 ; Figure 4 The enlarged view of B in Figure 3 ; Figure 5 This is an axial cross-sectional view of a first thrust bearing provided in one embodiment of this application. Figure 6 for Figure 5 Enlarged view of point C in the image; Figure 7 A schematic axial cross-sectional view of the second thrust bearing provided in one embodiment of this application. Figure 2 ; Figure 8 for Figure 7 Enlarged view of point D in the image; Figure 9 This is a three-dimensional structural schematic diagram of a second thrust bearing provided in one embodiment of this application; Figure 10 for Figure 9 Enlarged view of point E in the image; Figure 11 This is a bottom view of the structure of a second thrust bearing provided in one embodiment of this application; Figure 12 for Figure 11 Enlarged view of point F in the image; Figure 13 for Figure 11 Schematic diagram of the cross-sectional structure along line AA; Figure 14 for Figure 13 Enlarged view of point G in the image.

[0021] Explanation of key figure labels: 10. Housing; 11. First end; 12. Second end; 13. Air supply channel; 20. Shaft core; 30. Rotor disk; 40. First thrust bearing; 41. Air supply throttling orifice; 42. First flow equalization groove; 43. First air film gap; 44. Resonance cavity; 441. Cavity; 442. Neck section; 45. Bearing body; 46. Porous material structure; 50. Second thrust bearing; 51. First radial hole; 52. Second flow equalization groove; 53. Second air film gap; 54. Third air film gap; 60. Radial bearing; 61. Second radial hole; 62. Third flow equalization groove; 63. Fourth air film gap; 70. Rotary drive mechanism; 71. Stator; 72. Rotor; 80. Connecting seat; 90. Gap disk; 100. Cylinder; 110. Push-pull assembly; 120. Clamping assembly; 130. Machining tool. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0024] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0026] Traditional air-bearing spindles often require reduced torque output to achieve higher speeds. When machining micro-holes in thicker circuit boards, insufficient torque output can cause the cutting tool to jam in the material, leading to increased cutting temperatures, significantly shortened tool life, and even breakage. To address this, vibration-assisted drilling technology has been proposed. This technology superimposes high-frequency micro-amplitude vibrations onto the axial feed motion, transforming the cutting process from continuous to intermittent pecking-like cutting. This reduces the average cutting force, promotes chip refinement, and improves chip removal. However, existing solutions for vibration-assisted drilling mainly involve external excitation devices such as piezoelectric transducers and mechanical vibration devices, requiring significant modifications to the air-bearing spindle structure and increasing manufacturing costs.

[0027] Therefore, in order to solve the above problems, after in-depth research, an air-bearing spindle was designed. By setting a resonant cavity including a chamber and a constriction section on the first thrust bearing and / or the second thrust bearing, the frequency is locked by utilizing the Helmholtz resonance effect of the resonant cavity. Stable periodic pressure pulsations are generated under the action of gas. These periodic pressure pulsations are output to the air film gap through the constriction section, causing the gas pressure in the air film gap to change periodically. This drives the rotor disk to drive the shaft core to generate high-frequency reciprocating motion along the axial direction, which in turn drives the machining tool at the end of the shaft core to generate axial high-frequency vibration. Thus, when machining thicker and harder circuit boards, the cutting tool vibrates at high frequency during the cutting process, which can transform continuous cutting into intermittent pecking cutting. This causes the chips to be periodically broken into small fragments and easily discharged. At the same time, the tool disengages from the material at the bottom of the hole at the moment of vibration separation, and the cutting temperature is periodically relieved. The axial average cutting force is significantly reduced, effectively avoiding problems such as tool jamming and sharp rise in cutting temperature. This helps to extend the service life of the cutting tool and reduce the tool breakage rate, thereby improving the processing quality and efficiency and meeting the needs of micro-hole machining processes for increasingly thicker circuit boards.

[0028] Please refer to the following: Figures 1 to 14 The air-bearing spindle provided in the embodiments of this application will now be described.

[0029] Please see Figures 1 to 4 The air-bearing main shaft includes a shaft core 20, a first thrust bearing 40, and a second thrust bearing 50. A rotor disk 30 is mounted on the shaft core 20. The first thrust bearing 40 and the second thrust bearing 50 are both sleeved on the shaft core 20 and are located on both sides of the rotor disk 30 along the axial direction. Air film gaps are formed between the first thrust bearing 40 and the rotor disk 30, and between the second thrust bearing 50 and the rotor disk 30. Both the first thrust bearing 40 and the second thrust bearing 50 are provided with an air supply throttling structure, which is used to supply gas to the corresponding air film gap. The first thrust bearing 40 and / or the second thrust bearing 50 are provided with a resonance cavity 44. The resonance cavity 44 includes a cavity body 441 and a constricted section 442. One end of the constricted section 442 is connected to the cavity body 441, and the other end is connected to the corresponding air film gap. The cross-sectional area of ​​the constricted section 442 is smaller than the cross-sectional area of ​​the cavity body 441. The resonant cavity 44 can be configured to generate Helmholtz resonance under the action of gas to form periodic pressure pulsation. The periodic pressure pulsation is output to the corresponding gas film gap through the constriction section 442, so that the gas pressure in the gas film gap changes periodically, thereby driving the rotor disk 30 to drive the shaft core 20 to reciprocate along the axial direction, so that the shaft core 20 drives the machining tool 130 at its end to generate high-frequency vibration.

[0030] In this application, axial direction refers to the direction of the axis of the shaft core 20, circumferential direction refers to the circumferential direction around the axis of the shaft core 20, and radial direction refers to the radial direction along the shaft core 20, that is, the direction perpendicular to the axis of the shaft core 20.

[0031] One end of the shaft core 20 is used to connect to a machining tool 130, which can be a drill bit or a milling cutter, etc. A rotor disk 30 is arranged around the shaft core 20 and extends radially, rotating synchronously with the shaft core 20. Optionally, the rotor disk 30 and the shaft core 20 are integrally formed. The shaft core 20 and the rotor disk 30 are made of lightweight, high-strength materials, such as ceramic or alloy steel. Alternatively, the rotor disk 30 and the shaft core 20 can be a separate structure, where the rotor disk 30 is independently formed and fixedly fitted onto the shaft core 20 to ensure synchronous rotation. This can be achieved by using methods such as interference fit, key connection, or bonding to fix the rotor disk 30 onto the shaft core 20.

[0032] The rotor disk 30 has a first end face and a second end face arranged opposite each other along the axial direction. A first thrust bearing 40 is disposed on the side where the first end face is located, and a first air film gap 43 is formed between the first thrust bearing 40 and the first end face. A second thrust bearing 50 is disposed on the side where the second end face is located, and a second air film gap 53 is formed between the second thrust bearing 50 and the second end face. The air supply throttling structure on the first thrust bearing 40 is used to supply gas to the first air film gap 43 between the first thrust bearing 40 and the first end face, so that a first axial air film is formed in the first air film gap 43, and the first axial air film is used to axially support the first end face of the rotor disk 30. The air supply throttling structure on the second thrust bearing 50 is used to supply gas to the second air film gap 53 between the second thrust bearing 50 and the second end face, so that a second axial air film is formed in the second air film gap 53, and the second axial air film is used to axially support the second end face of the rotor disk 30. Understandably, the first axial air film and the second axial air film act on the first end face and the second end face of the rotor disk 30 along the axial direction, respectively, so that the rotor disk 30 and the shaft core 20 are in a suspended state along the axial direction. As a result, when the shaft core 20 rotates at high speed, the shaft core 20 does not contact the first thrust bearing 40 and the second thrust bearing 50 and other surrounding components in the axial direction, which helps to reduce the wear of the shaft core 20 and its surrounding components, and at the same time helps to improve the stability of the shaft core 20 when rotating at high speed.

[0033] Optionally, the first thrust bearing 40 and / or the second thrust bearing 50 having a resonant cavity 44 means that both the first thrust bearing 40 and the second thrust bearing 50 have a resonant cavity 44; or, the resonant cavity 44 is only provided on the first thrust bearing 40; or, the resonant cavity 44 is only provided on the second thrust bearing 50. The specific choice can be made according to the required vibration excitation intensity and structural design requirements. When the resonant cavity 44 is only provided on the first thrust bearing 40 or the second thrust bearing 50, periodic pressure pulsations are generated in the air film gap on the side corresponding to the resonant cavity 44, while the gas pressure in the air film gap on the other side remains relatively stable. A periodic pressure difference is formed between the air films on both sides of the rotor disk 30, thereby driving the rotor disk 30 to drive the shaft core 20 to reciprocate axially. When both the first thrust bearing 40 and the second thrust bearing 50 are provided with resonant cavities 44, the phase difference between the resonant cavities 44 on both sides of the rotor disk 30 can be designed so that the periodic pressure pulsations generated on both sides of the rotor disk 30 can alternately act on the first end face and the second end face of the rotor disk 30, forming a push-pull oscillation, which is beneficial to increase the axial vibration amplitude and improve the symmetry of the vibration.

[0034] Optionally, the cavity 441 can be cylindrical, hemispherical, or rectangular; it can also be formed by a combination of at least two of these shapes along the axial direction. For example, the cavity 441 can be a cylindrical concave cavity or a hemispherical concave cavity. The volume V of the cavity 441 is one of the core parameters determining the resonant frequency. In specific design, the volume V of the cavity 441 can be calculated and determined using the Helmholtz resonant frequency formula based on the target vibration frequency and the parameters of the constricted section 442.

[0035] Combination Figure 3 and Figure 4 Optionally, the necked section 442 can be a single through hole, with its two ends connected to the cavity 441 and the air film gap, respectively. Alternatively, the necked section 442 can be a micropore array, comprising multiple spaced through holes, each with its two ends connected to the cavity 441 and the air film gap. When a micropore array is used as the necked section 442, the total cross-sectional area of ​​the multiple through holes is equivalent to the cross-sectional area of ​​the necked section 442. This increases the circumferential uniformity of the necked section 442 while maintaining the total cross-sectional area, which is beneficial for more uniform pressure pulsation acting on the rotor disk 30.

[0036] Optionally, the constricted section 442 is coaxially arranged with the cavity 441.

[0037] It is understandable that the resonant cavity 44 is constructed as a Helmholtz resonant cavity, and its resonant frequency f satisfies the following relationship:

[0038] Where f is the resonant frequency of the resonant cavity 44 in Hz; c is the speed of sound in m / s, determined by the type and temperature of the supplied gas; A is the cross-sectional area of ​​the constricted section 442 in m²; when the constricted section 442 is a micropore array, A is the sum of the cross-sectional areas of all the through-holes; V is the volume of the cavity 441 in m³; and L is the axial length of the constricted section 442 in m. By setting at least one of A, V, and L, the resonant frequency of the resonant cavity 44 can be matched with the frequency of the axial reciprocating motion of the shaft core 20, thereby achieving frequency locking and obtaining a stable high-frequency vibration output. In specific design, the resonant frequency of the resonant cavity 44 can be set to the target value by adjusting one or more parameters of the cavity 441 volume V, the cross-sectional area A of the constricted section 442, and the axial length L of the constricted section 442, according to the target vibration frequency. For example, increasing the volume V of cavity 441 will lower the resonant frequency, increasing the cross-sectional area A of constricted section 442 will increase the resonant frequency, and increasing the axial length L of constricted section 442 will lower the resonant frequency.

[0039] Optionally, the cross-sectional area A of the constricted section 442 is 0.5 mm² to 20 mm²; the volume V of the cavity 441 is 0.025 mm³ to 100 mm³; and the axial length L of the constricted section 442 is 0.05 mm to 5 mm.

[0040] For example, the resonant cavity 44 is connected to the corresponding air supply throttling structure. The working principle of the resonant cavity 44 is as follows: After the compressed gas enters the cavity 441 through the air supply throttling structure, pressure fluctuations are formed within the cavity 441. The gas in the cavity 441 is ejected into the gas film gap through the constriction section 442. At the edge of the opening of the constriction section 442, the airflow velocity changes abruptly, forming an unstable shear layer. This shear layer is extremely sensitive to minute disturbances. At a preset flow rate, the shear layer rolls up to form periodically shedding vortices. The pressure waves generated by the vortex shedding are coupled with the gas spring effect within the cavity 441, forming vortex resonance. When the vortex shedding frequency matches the Helmholtz natural frequency of the resonant cavity 44, it enters a self-sustaining oscillation state: the vortex shedding generates pressure waves, the pressure waves excite the cavity 441 to resonate, the resonance enhances the pressure waves, and the enhanced pressure waves promote more regular vortex shedding, thus reinforcing in a cyclical manner. The high-frequency pressure wave generated by the resonant cavity 44 is ejected through the opening of the constricted section 442, passes through the gas film gap, and directly acts on the end face of the rotor disk 30, such as the first end face or the second end face, causing the gas pressure in the gas film gap to change periodically. When a periodic pressure difference is formed between the gas film gaps on both sides of the rotor disk 30, the rotor disk 30 is driven to drive the shaft core 20 to reciprocate axially, and then the shaft core 20 drives the machining tool 130 to vibrate.

[0041] Combination Figure 5 and Figure 6It is understandable that the first thrust bearing 40 is provided with multiple resonant cavities 44 distributed circumferentially. The multiple resonant cavities 44 are evenly distributed circumferentially, and the parameters such as the volume of the cavity 441, the cross-sectional area of ​​the necking section 442, and the axial length of the necking section 442 of each resonant cavity 44 are consistent, so as to ensure that the excitation force generated by each resonant cavity 44 is uniform circumferentially.

[0042] Optionally, the first thrust bearing 40 has 4 to 12 resonant cavities 44, for example, 6. When the number of resonant cavities 44 is less than 4, the uniformity of the circumferential excitation force is insufficient, which may cause uneven force on the rotor disk 30 and result in sway. When the number of resonant cavities 44 is more than 12, the spacing between adjacent resonant cavities 44 is too small, which increases the difficulty of processing. Furthermore, the small solid area between the cavities 441 may affect the structural strength of the bearing and the gas film sealing effect.

[0043] Combination Figure 3 and Figure 4 It is understandable that the second thrust bearing 50 is provided with multiple resonant cavities 44 distributed circumferentially. The multiple resonant cavities 44 are evenly distributed circumferentially, and the parameters such as the volume of the cavity 441, the cross-sectional area of ​​the necked section 442, and the axial length of the necked section 442 of each resonant cavity 44 are consistent, so as to ensure that the excitation force generated by each resonant cavity 44 is uniform circumferentially.

[0044] Optionally, the second thrust bearing 50 has 4 to 12 resonant cavities 44, for example, 6. When the number of resonant cavities 44 is less than 4, the uniformity of the circumferential excitation force is insufficient, which may cause uneven force on the rotor disk 30 and result in sway. When the number of resonant cavities 44 is more than 12, the spacing between adjacent resonant cavities 44 is too small, which increases the difficulty of processing, and the solid area between the cavities 441 is too small, which may affect the structural strength of the bearing and the gas film sealing effect.

[0045] Combination Figure 1 and Figure 2 It is understood that the gas supply throttling structure includes a gas supply throttling orifice 41. The gas supply throttling orifice 41 has an inlet end and an outlet end. The inlet end of the gas supply throttling orifice 41 is used to connect to the gas supply channel 13, and the outlet end of the gas supply throttling orifice 41 is used to output pressurized gas. A resonant cavity 44 is provided on the first thrust bearing 40. On the first thrust bearing 40, the outlet end of the gas supply throttling orifice 41 is directly connected to the cavity 441 of the corresponding resonant cavity 44. And / or, a resonant cavity 44 is provided on the second thrust bearing 50. On the second thrust bearing 50, the outlet end of the gas supply throttling orifice 41 is directly connected to the cavity 441 of the corresponding resonant cavity 44.

[0046] Combination Figure 3 and Figure 4Optionally, a resonant cavity 44 is provided on the first thrust bearing 40, and the outlet end of the air supply throttle orifice 41 on the first thrust bearing 40 is located on the bottom wall of the corresponding cavity 441. And / or, a resonant cavity 44 is provided on the second thrust bearing 50, and the outlet end of the air supply throttle orifice 41 on the second thrust bearing 50 is located on the bottom wall of the corresponding cavity 441. Gas flowing out through the outlet end of the air supply throttle orifice 41 enters from the bottom of the corresponding cavity 441, fills the cavity 441, and is ejected through the corresponding constricted section 442. The airflow fully participates in resonance, resulting in a strong excitation effect.

[0047] Furthermore, the first thrust bearing 40 is provided with a resonant cavity 44. An air supply throttling orifice 41 is coaxially arranged with the resonant cavity 44 on the first thrust bearing 40, meaning the axis of the air supply throttling orifice 41 coincides with the axis of the cavity 441 and the constricted section 442. This allows airflow to enter along the central axis of the cavity 441, forming a uniform pressure field within the cavity 441, further improving energy conversion efficiency. And / or, the second thrust bearing 50 is provided with a resonant cavity 44. An air supply throttling orifice 41 is coaxially arranged with the resonant cavity 44 on the second thrust bearing 50, meaning the axis of the air supply throttling orifice 41 coincides with the axis of the cavity 441 and the constricted section 442. This allows airflow to enter along the central axis of the cavity 441, forming a uniform pressure field within the cavity 441, further improving energy conversion efficiency.

[0048] Optionally, the outlet end of the air supply throttle orifice 41 is located on the side wall of the corresponding cavity 441. The gas flowing out through the outlet end of the air supply throttle orifice 41 enters from the side wall of the cavity 441, forms a swirling flow in the cavity 441, and is ejected through the constricted section 442. The swirling flow enhances vortex-acoustic coupling and has a strong excitation effect.

[0049] Combination Figures 9 to 14Alternatively, the first thrust bearing 40 may have a resonant cavity 44. On the first thrust bearing 40, the outlet end of the air supply throttling orifice 41 is directly connected to the corresponding gas film gap and is located adjacent to the constricted section 442. That is, the air supply throttling orifice 41 is located outside the cavity 441 and is not directly connected to the cavity 441 of the corresponding resonant cavity 44. The second thrust bearing 50 may also have a resonant cavity 44. On the second thrust bearing 50, the outlet end of the air supply throttling orifice 41 is directly connected to the corresponding gas film gap and is located adjacent to the constricted section 442. That is, the air supply throttling orifice 41 is located outside the cavity 441 and is not directly connected to the cavity 441 of the corresponding resonant cavity 44. High-pressure gas flowing from the air supply throttling orifice 41 is first sprayed onto the rotor disk 30, impacts the rotor disk 30, and then spreads out along the gas film gap. Part of the gas flows back to the adjacent cavity 441, gathers and is compressed, and participates in the self-sustaining vortex oscillation at the necking section 442. This adjacent arrangement eliminates the need for direct connection or precise alignment between the air supply throttling orifice 41 and the resonant cavity 44, reducing machining difficulty. Furthermore, the air supply throttling orifice 41 directly supplies gas to the gas film gap, resulting in more direct gas film pressure establishment, higher gas film stiffness, and stronger axial load capacity of the spindle. Understandably, the resonant cavity 44 and the air supply throttling orifice 41 can be directly connected or adjacent, depending on different requirements such as excitation response speed, vibration stability, machining difficulty, and axial load capacity. Both of these arrangements can be applied to the first thrust bearing 40 and / or the second thrust bearing 50.

[0050] Combination Figure 1 and Figure 2 It is understood that the air supply throttling structure includes multiple circumferentially spaced air supply throttling orifices 41, and each resonant cavity 44 is connected to at least one air supply throttling orifice 41. The number of air supply throttling orifices 41 is from four to twelve, and they are evenly distributed circumferentially. For example, the number of air supply throttling orifices 41 is six.

[0051] Optionally, the number of air supply throttling orifices 41 is equal to the number of resonant cavities 44, with each resonant cavity 44 corresponding to one air supply throttling orifice 41. Of course, in other embodiments, each resonant cavity 44 may also correspond to multiple air supply throttling orifices 41 to increase the air supply and improve the excitation intensity.

[0052] Optionally, the diameter of the air supply throttling orifice 41 is between 0.15 mm and 0.50 mm. This orifice diameter range ensures sufficient air supply flow while achieving effective throttling and pressure reduction. When the diameter of the air supply throttling orifice 41 is less than 0.15 mm, the air supply flow is insufficient, which may lead to a decrease in air film stiffness and increase the difficulty of machining the small orifice. When the diameter of the air supply throttling orifice 41 is greater than 0.50 mm, the throttling and pressure reduction effect is weakened, the airflow velocity decreases, which is not conducive to the formation of shear layer vortices and may affect the resonant vibration initiation effect.

[0053] CombinationFigure 3 and Figure 4 It is understandable that the first thrust bearing 40 and / or the second thrust bearing 50 are made of metal, such as bearing steel or stainless steel, and their end faces facing the rotor disk 30 are precision-machined surfaces with a surface roughness Ra of no more than 0.4 μm, and their flatness meets the design requirements of gas static pressure bearings. By using both the first thrust bearing 40 and the second thrust bearing 50 as integrally formed metal materials, there is no risk of material detachment, making it suitable for scenarios with high cleanliness requirements and stable gas supply.

[0054] For example, the outlet end of the air supply throttling orifice 41 is located on the side wall of the corresponding cavity 441. When both the first thrust bearing 40 and the second thrust bearing 50 are made of metal, the working principle for the rotor disk 30 to drive the shaft core 20 in axial reciprocating motion is shear layer vortex-induced acoustic coupling self-excited oscillation. Specifically, compressed gas is ejected at high speed from the outlet end of the air supply throttling orifice 41 and enters the cavity 441 of the resonant cavity 44. Due to the throttling and pressure reduction effect of the air supply throttling orifice 41, the airflow forms a high-speed jet within the cavity 441. The gas within the cavity 441 is ejected into the gas film gap through the constricted section 442. At the edge of the constricted section 442, the airflow velocity changes abruptly, forming an unstable shear layer. This shear layer is extremely sensitive to minute disturbances. At a preset flow rate, the shear layer rolls up to form periodically shedding vortices. The shedding frequency of each vortex is determined by parameters such as the volume V of the cavity 441 of the resonant cavity 44, the cross-sectional area A of the constricted section 442, and the axial length L of the constricted section 442. The pressure wave generated by the vortex shedding couples with the gas spring effect within the cavity 441, forming vortex resonance. When the vortex shedding frequency matches the Helmholtz natural frequency of the resonant cavity 44, the system enters a self-sustaining oscillation state: the vortex shedding generates a pressure wave, the pressure wave excites the cavity 441 to resonate, the resonance amplifies the pressure wave, and the amplified pressure wave promotes more regular vortex shedding, thus reinforcing the cycle. The high-frequency pressure wave generated by the resonant cavity 44 is ejected through the opening of the constricted section 442, passes through the extremely thin gas film gap, and directly acts on the end face of the rotor disk 30. When the excitation frequency matches the natural frequency, resonance occurs, driving the shaft core 20 to generate stable axial high-frequency micro-vibrations.

[0055] Combination Figures 5 to 8It is understood that the first thrust bearing 40 and / or the second thrust bearing 50 include a bearing body 45 and a porous material structure 46. The porous material structure 46 is disposed on the end face of the bearing body 45 facing the rotor disk 30, and the porous material structure 46 has multiple micropores inside. The resonant cavity 44 is disposed on the bearing body 45 and / or the porous material structure 46. Specifically, the resonant cavity 44 is directly formed on the bearing body 45; or, the resonant cavity 44 is directly formed on the porous material structure 46; or, the resonant cavity 44 is formed in the interface region between the porous material structure 46 and the bearing body 45, for example, the cavity 441 is formed inside the bearing body 45, and the necked section 442 penetrates the porous material structure 46.

[0056] Optionally, the porous material structure 46 extends axially in a ring shape and covers at least a portion of the end face of the bearing body 45 facing the rotor disk 30; for example, the porous material structure 46 is annular and covers the entire end face of the bearing body 45 facing the rotor disk 30. Alternatively, the porous material structure 46 may include a plurality of circumferentially spaced arcuate segments, which together cover the end face of the bearing body 45.

[0057] It is understood that the porous material structure 46 includes at least one of a porous polyetheretherketone layer, a porous graphite layer, a porous carbon fiber layer, a porous graphene layer, a porous metal layer, and a porous ceramic layer. The porosity of the porous material structure 46 is 15% to 40%, for example, 17% to 20%. The porous material structure 46 has a large number of uniformly distributed micropore channels inside, which generate a distributed throttling effect when compressed gas passes through the porous material structure 46.

[0058] The micropores of the porous material structure 46 constitute at least a part of the gas supply throttling structure, and the micropores are used to supply gas to the gas film gap. Specifically, after compressed gas enters the porous material structure 46, it is uniformly supplied to the corresponding gas film gap through the distributed throttling effect of the micropores, forming a gas film within the gas film gap.

[0059] Combination Figure 6 and Figure 8 It is understood that, based on the fact that the micropores of the porous material structure 46 constitute at least a part of the air supply throttling structure, the air supply throttling structure also includes an air supply throttling orifice 41. The air supply throttling orifice 41 is disposed through the porous material structure 46, and the diameter of the air supply throttling orifice 41 is larger than the diameter of the micropores. The air supply throttling orifice 41 and the micropores are used to simultaneously supply air to the gas film gap. At this time, the resonant cavity 44 is disposed on the porous material structure 46, and the cavity 441 is connected to at least one air supply throttling orifice 41 and at least one micropore.

[0060] For example, when both the first thrust bearing 40 and the second thrust bearing 50 include a bearing body 45 and a porous material structure 46, the working principle for the rotor disk 30 to drive the shaft core 20 to reciprocate axially is based on the synergy of broadband excitation and narrow-band amplification. Specifically, compressed gas enters the porous material structure 46 through the gas supply channel 13. Because the porous material structure 46 has a large number of randomly distributed micropores of varying sizes, the gas experiences a weak throttling effect and local pressure fluctuations when passing through each micropore. The pressure fluctuations from the numerous micropores superimpose to form a weak pressure disturbance covering a wide frequency band in the gas film gap. This disturbance persists and is unaffected by small fluctuations in the gas supply pressure. When the broadband disturbance propagates to the resonant cavity 44 region, the resonant cavity 44 constitutes a Helmholtz resonator with a definite natural frequency. Cavity 441 performs frequency filtering on broadband disturbances, generating a resonant response only for disturbance components with the same natural frequency. The resonant response amplifies the weak disturbance energy by tens to hundreds of times, converting it into high-energy single-frequency pressure pulsations, while disturbance components deviating from the natural frequency are suppressed or attenuated. The high-frequency pressure pulsations generated by resonant cavity 44 are output to the corresponding gas film gap through necking section 442, directly acting on the end face of rotor disk 30, causing the gas pressure in the gas film gap to change periodically, driving rotor disk 30 to drive shaft core 20 to reciprocate axially. Understandably, by utilizing the broadband disturbance characteristics of porous material structure 46 and the frequency selective amplification characteristics of resonant cavity 44 in synergy, a wider start-up pressure window and stronger resistance to gas supply fluctuations are achieved, making it suitable for scenarios with high reliability requirements and a wide operating window.

[0061] Combination Figure 1 and Figure 2 It is understood that the air-bearing main shaft also includes a gap disk 90. ​​The gap disk 90 is disposed between the first thrust bearing 40 and the second thrust bearing 50, and surrounds the rotor disk 30, to define the thickness of the air film gap. The gap disk 90 is annular in shape, and its axial thickness is greater than that of the rotor disk 30, so that air film gaps can be formed between the rotor disk 30 and the first thrust bearing 40, and between the rotor disk 30 and the second thrust bearing 50.

[0062] Optionally, the thickness of the air film gap is between 5 μm and 40 μm. A thinner air film gap can improve the axial air film stiffness and the natural frequency of the air-bearing spindle, allowing the natural frequency of the air-bearing spindle to match the excitation frequency generated by the resonant cavity 44, thus achieving resonance enhancement. When the air film gap thickness is less than 5 μm, the requirements for the machining and assembly accuracy of the parts are too high, and contact friction is easily caused by thermal expansion; when the air film gap thickness is greater than 40 μm, the air film stiffness is insufficient, and the natural frequency of the air-bearing spindle is too low, which may not be able to match the high-frequency excitation frequency of the resonant cavity 44, affecting the resonance enhancement effect.

[0063] Optionally, the flatness error of the end face of the gap disk 90 is no greater than 1 μm. The parallelism error of the two opposite end faces of the gap disk 90 is no greater than 2 μm. High-precision flatness and parallelism can ensure that the air film gap is uniformly distributed along the circumference, ensuring that the excitation force generated by each resonant cavity 44 is uniformly applied to the rotor disk 30, avoiding axial sway and vibration instability caused by uneven air film gap.

[0064] It is understood that the frequency of the axial reciprocating motion of the shaft core 20 is from 0.1kHz to 40kHz, and the amplitude of the axial reciprocating motion of the shaft core 20 is from 1.0μm to 30μm. This frequency and amplitude range can meet the requirements of vibration-assisted drilling in the micro-hole machining of circuit boards. The vibration frequency is determined by the Helmholtz resonance frequency of the resonant cavity 44, and can be set within the above range by adjusting the parameters of the resonant cavity 44; the vibration amplitude is determined by the air supply pressure, the parameters of the resonant cavity 44, and the air film gap, and can be controlled within the above range by adjusting the air supply pressure. When the vibration frequency is below 0.1kHz, the vibration-assisted cutting effect is not obvious, and it is difficult to effectively break chips and reduce cutting temperature; when the vibration frequency is above 40kHz, the machining accuracy requirements of the resonant cavity 44 are extremely high, and high-frequency vibration may lead to a decrease in the fatigue life of the air-bearing spindle. When the amplitude is less than 1.0μm, the separation between the machining tool 130 and the bottom material of the hole is insufficient, and the vibration-assisted cutting effect is weak; when the amplitude is greater than 30μm, it may affect the geometric accuracy and surface quality of the machined hole.

[0065] Combination Figure 1 It is understood that a third air film gap 54 is formed between the inner wall of the second thrust bearing 50 and the shaft core 20. The inner wall of the second thrust bearing 50 is provided with multiple first radial holes 51 communicating with the third air film gap 54, and these first radial holes 51 are evenly distributed circumferentially. Pressurized gas enters the third air film gap 54 through the first radial holes 51 and forms a radial air film to provide radial support for the shaft core 20, ensuring its radial balance. By designing the second thrust bearing 50 to simultaneously provide axial thrust support and radial support, it is beneficial to simplify the structure and improve integration.

[0066] Optionally, the plurality of first radial holes 51 are arranged in at least two rows along the axial direction to provide sufficient radial support stiffness, ensuring that the radial rotation accuracy of the shaft core 20 is not affected while generating axial high-frequency vibration, and effectively suppressing the sway of the shaft core 20.

[0067] Combination Figure 1The air-bearing spindle also includes a radial bearing 60, which is sleeved on the spindle core 20. A fourth air film gap 63 is formed between the inner wall of the radial bearing 60 and the spindle core 20. The inner wall of the radial bearing 60 is provided with a plurality of second radial holes 61 communicating with the fourth air film gap 63, and the plurality of second radial holes 61 are distributed circumferentially. Pressurized gas enters the fourth air film gap 63 through the second radial holes 61 and forms a radial air film to provide radial support for the spindle core 20. The radial air film of the second thrust bearing 50 and the radial air film of the radial bearing 60 together constitute a multi-point radial support system, ensuring the rotational accuracy of the spindle core 20 and the radial runout control of the machining tool 130.

[0068] Optionally, the plurality of second radial holes 61 of the radial bearing 60 are arranged in at least two rows along the axial direction to ensure the radial support stiffness of the spindle 20 at the end of the machining tool 130.

[0069] Combination Figure 1 The air-bearing main shaft also includes a housing 10. A shaft core 20 is rotatably mounted within the housing 10. The rotor disk 30, the first thrust bearing 40, the second thrust bearing 50, and the radial bearing 60 are all housed within the housing 10. The housing 10 is provided with an air supply channel 13, which communicates with each air supply throttling structure, the first radial hole 51, and the second radial hole 61. The housing 10 provides support and protection for all internal components. The air supply channel 13 is integrated within the housing 10, enabling centralized supply and distribution of pressurized gas.

[0070] The housing 10 has a first end 11 and a second end 12 disposed opposite to each other along the axial direction, and one end of the shaft core 20 extends from the first end 11 to the outside of the housing 10 for connecting the machining tool 130.

[0071] The axial positions of the first thrust bearing 40, the second thrust bearing 50, and the radial bearing 60 within the housing 10 can be arranged in various ways: for example, the first thrust bearing 40 and the second thrust bearing 50 can be located at the first end 11, and the radial bearing 60 at the second end 12; or the radial bearing 60 can be located at the first end 11, and the first thrust bearing 40 and the second thrust bearing 50 at the second end 12; or the first thrust bearing 40 and the second thrust bearing 50 can be located in the middle of the housing 10, and the radial bearing 60 can be located at either the first end 11 or the second end 12. Different arrangements are suitable for different spindle structure design requirements and can be selected based on overhang length, stiffness requirements, and ease of assembly.

[0072] Combination Figure 1 and Figure 2It is understood that the outer wall of the first thrust bearing 40 is provided with a first flow equalization groove 42, which is an annular groove extending circumferentially. The air supply channel 13 is connected to each air supply throttling orifice 41 on the first thrust bearing 40 through the first flow equalization groove 42. The pressurized gas in the air supply channel 13 flows evenly to each air supply throttling orifice 41 on the first thrust bearing 40 through the first flow equalization groove 42, which enables the pressurized gas entering the first thrust bearing 40 to be evenly distributed in the first flow equalization groove 42, and then stably and evenly delivered to the first air film gap 43 through each air supply throttling orifice 41, ensuring that the air film pressure in the first air film gap 43 is evenly distributed circumferentially.

[0073] Combination Figure 1 and Figure 2 It is understood that the outer wall of the second thrust bearing 50 is provided with a second flow equalization groove 52, which is an annular groove extending circumferentially. The air supply channel 13 is connected to each air supply throttling orifice 41 and each first radial orifice 51 on the second thrust bearing 50 through the second flow equalization groove 52. The pressurized gas in the air supply channel 13 flows evenly to each air supply throttling orifice 41 and each first radial orifice 51 on the second thrust bearing 50 through the second flow equalization groove 52, so that a single air supply channel 13 can simultaneously supply air for radial support and axial thrust, which is beneficial to simplifying the air circuit structure.

[0074] Combination Figure 1 and Figure 2 It is understood that the outer wall of the radial bearing 60 is provided with a third flow equalization groove 62, which is an annular groove extending circumferentially. The air supply channel 13 is connected to each of the second radial holes 61 through the third flow equalization groove 62. The pressurized gas in the air supply channel 13 flows evenly to each of the second radial holes 61 through the third flow equalization groove 62, ensuring that the radial air film pressure in the fourth air film gap 63 is evenly distributed circumferentially.

[0075] Combination Figure 1 It is understood that the air-bearing main shaft also includes a rotary drive mechanism 70, which is located inside the housing 10 and is used to drive the shaft core 20 to rotate. The rotary drive mechanism 70 includes a stator 71 and a rotor 72. The stator 71 is fixed to the inner wall of the housing 10, and the rotor 72 is disposed on the outer circular surface of the shaft core 20 and is radially spaced relative to the stator 71. When alternating current is applied to the stator 71, a rotating magnetic field is generated. Under the action of the rotating magnetic field, the rotor 72 generates an induced current and electromagnetic torque, driving the shaft core 20 to rotate.

[0076] Optionally, the stator 71 is a drive winding, which is annular and sleeved around the shaft core 20, with an air gap between them. An annular groove is formed on the outer surface of the shaft core 20 corresponding to the axial position of the drive winding. The rotor 72 is an induction squirrel-cage rotor and is embedded in the annular groove, with the outer surface of the rotor 72 flush with or slightly lower than the outer surface of the shaft core 20. This integrated embedded structure improves reliability at ultra-high speeds while reducing the radial dimension occupied by the rotor 72, which is beneficial to the uniformity of the air gap in the drive winding.

[0077] The housing 10, together with the first thrust bearing 40, the second thrust bearing 50, the stator 71, and the radial bearing 60, forms a cooling passage. The cooling medium within the cooling passage can flow through the first thrust bearing 40, the second thrust bearing 50, the stator 71, and the radial bearing 60. The cooling medium flows through the cooling passage to each heat-generating component to cool and reduce the heat generated by the windings and gas friction of the stator 71. This prevents problems such as performance degradation, accelerated wear, or even damage due to excessive temperature, and helps to improve the overall operational stability, reliability, and service life of the air-bearing spindle.

[0078] Combination Figure 1 It is understood that the air-bearing main shaft also includes a connecting seat 80, which is connected to the second end 12 of the housing 10. The connecting seat 80 is provided with a first connecting port, a second connecting port, and a third connecting port. The first connecting port is connected to the air supply channel 13 for supplying pressurized gas. The second connecting port is connected to one end of the cooling channel for supplying cooling medium. The third connecting port is connected to the other end of the cooling channel for supplying cooling medium.

[0079] The gas supply system inputs high-pressure gas into the gas supply channel 13 through the first connection port, and delivers it to the gas paths of the first thrust bearing 40, the second thrust bearing 50, and the radial bearing 60, respectively, and connects with the gas supply throttling orifice 41, the first radial hole 51, and the second radial hole 61. The cooling system inputs cooling medium into the cooling passage through the second connection port, and delivers it to the circulating cooling passages of the second thrust bearing 50, the stator 71, and the radial bearing 60, respectively, to cool down the winding heating and gas friction heating. The cooled medium after heat exchange flows out from the third connection port.

[0080] Combination Figure 1It is understood that the spindle core 20 has a hollow structure with a hollow inner hole extending along the axial direction. The air-bearing spindle also includes a cylinder 100, a push-pull assembly 110, and a clamping assembly 120. The cylinder 100 is connected to the second end 12 of the housing 10, specifically, the cylinder 100 is fixedly mounted on the connecting seat 80. The clamping assembly 120 is movably inserted into the spindle core 20, with one end protruding from the first end 11 of the housing 10, for clamping the machining tool 130. The push-pull assembly 110 is movably disposed inside the spindle core 20, with one end connected to the cylinder 100 and the other end connected to the clamping assembly 120. Driven by the cylinder 100, the push-pull assembly 110 drives the clamping assembly 120 to move axially, thereby controlling the clamping assembly 120 to clamp or release the machining tool 130.

[0081] Specifically, the clamping component 120 is an elastic gripper and is disposed in the inner hole at the front end of the shaft core 20. When the cylinder 100 is ventilated, the push-pull component 110 moves forward axially, and the front end of the push-pull component 110 presses against the clamping component 120. Under the action of the axial thrust, the clamping component 120 slides open along the conical surface of the inner hole at the front end of the shaft core 20, releasing the old drill bit being clamped. When the cylinder 100 is ventilated in the reverse direction or vented, the push-pull component 110 retracts, and the clamping component 120 closes under the action of its own elastic restoring force, clamping the newly installed drill bit.

[0082] A radial clearance is maintained between the push-pull assembly 110 and the hollow inner wall of the shaft core 20. The push-pull assembly 110 does not rotate with the shaft core 20; it remains stationary when the shaft core 20 rotates. The push-pull assembly 110 only generates axial linear motion during tool changing operations. During normal machining, the push-pull assembly 110 is in the retracted position, does not contact the clamping assembly 120, and does not affect the free rotation and axial high-frequency vibration of the shaft core 20.

[0083] Optionally, cylinder 100 can be a double-acting cylinder or a single-acting cylinder. A double-acting cylinder has a first port and a second port. When pressurized gas is introduced into the first port, it drives the push-pull assembly 110 to extend and open the clamping assembly 120. When pressurized gas is introduced into the second port, it drives the push-pull assembly 110 to retract. A single-acting cylinder drives the push-pull assembly 110 to extend when pressurized gas is introduced, and its own elastic reset component drives the push-pull assembly 110 to retract when the gas is exhausted. The extension and retraction of the double-acting cylinder are both pneumatically driven, ensuring reliable operation and controllable speed. The single-acting cylinder has a simple structure and low gas consumption, making it suitable for scenarios where retraction speed requirements are not high.

[0084] For example, when the air-bearing spindle provided in this application is working, compressed gas enters the air supply channel 13 inside the housing 10 through the first connection port of the connecting seat 80. After being distributed by the first equalization groove 42, the second equalization groove 52 and the third equalization groove 62, it enters the air supply throttling orifice 41 of the first thrust bearing 40, the air supply throttling orifice 41 and the first radial hole 51 of the second thrust bearing 50, and the second radial hole 61 of the radial bearing 60, respectively. The air supply throttling orifice 41 of the first thrust bearing 40 and the air supply throttling orifice 41 of the second thrust bearing 50 inject high-pressure gas into the cavity 441 of the resonant cavity 44. The gas is ejected through the constriction section 442 to the first air film gap 43 and the second air film gap 53. The resonant cavity 44 generates Helmholtz resonance under the action of gas, forming periodic pressure pulsations. These periodic pressure pulsations are output to the air film gap through the necking section 442, forming a thrust air film within the air film gap to provide axial support for the shaft core 20. This causes the gas pressure within the air film gap to change periodically, driving the rotor disk 30 to generate high-frequency micro-vibrations along the axial direction of the shaft core 20. Simultaneously, the first radial hole 51 and the second radial hole 61 supply gas to the third air film gap 54 and the fourth air film gap 63, respectively, forming radial air films to provide multi-point radial support for the shaft core 20, ensuring the rotational accuracy of the shaft core 20. The rotary drive mechanism 70 drives the shaft core 20 to rotate at high speed. The machining tool 130 at the end of the shaft core 20 vibrates axially at high speed while rotating at high speed, achieving vibration-assisted drilling. The cooling medium enters the cooling passage through the second connection port of the connecting seat 80, flows through each heat-generating component, and then flows out from the third connection port to cool the spindle. When changing tools, the cylinder 100 drives the push-pull assembly 110 to push the clamping assembly 120 forward, causing the clamping assembly 120 to open and release the old machining tool 130; after the new machining tool 130 is loaded, the cylinder 100 exhausts air or vents in the reverse direction, the push-pull assembly 110 retracts, and the clamping assembly 120 closes and clamps the new machining tool 130.

[0085] The beneficial effects of the air-bearing spindle provided in this application include at least the following: 1. By setting a resonant cavity 44, including a cavity 441 and a necking section 442, on the first thrust bearing 40 and / or the second thrust bearing 50, frequency locking is achieved using the Helmholtz resonance effect of the resonant cavity 44. Stable periodic pressure pulsations are generated under the action of gas. These periodic pressure pulsations are output to the gas film gap through the necking section 442, causing the gas pressure in the gas film gap to change periodically. This drives the rotor disk 30 to drive the shaft core 20 to generate high-frequency axial reciprocating motion, which in turn drives the machining tool 130 to generate axial high-frequency micro-amplitude vibration synchronously. This causes the machining tool 130 to superimpose high-frequency micro-amplitude vibration on the axial feed motion, transforming continuous cutting into intermittent pecking cutting. For micro-hole drilling of circuit boards, this vibration mode causes the chips to be periodically broken into small fragments, which are easily discharged through the spiral groove. The tool is separated from the bottom material of the hole at the moment of vibration separation, the cutting temperature is periodically relieved, and the average axial cutting force is reduced. This helps to suppress burrs at the hole opening, reduce drill wear, reduce the breakage rate, extend the tool life, and improve machining quality and efficiency.

[0086] In addition, the vibration excitation action comes from the main spindle's own air supply system, which only involves machining the resonant cavity 44 on the thrust bearing. It does not require external excitation devices such as external piezoelectric transducers or mechanical vibration devices, and does not change the original structure of the stator 71, rotor 72, radial bearing 60, etc. It also does not change the original rotational parameters, speed characteristics and radial accuracy of the air-bearing main spindle. The processing and manufacturing cost is low, which makes it easy to promote and apply to existing air-bearing main spindle products.

[0087] 2. This application achieves the locking of the Helmholtz resonant frequency by using the geometric parameters of the cavity 441 volume V, the cross-sectional area A of the constricted section 442, and the axial length L of the constricted section 442. By adjusting the cavity 441 volume, the cross-sectional area of ​​the constricted section 442, and the axial length, the resonant frequency can be set to the target value, thereby obtaining a stable high-frequency vibration output, and the adjustment is simple.

[0088] 3. This application provides two implementation methods: the first thrust bearing 40 and / or the second thrust bearing 50 are pure metal structures, and the first thrust bearing 40 and / or the second thrust bearing 50 contain a porous material structure 46. The former utilizes the vortex-induced acoustic coupling self-excited oscillation of the pure metal structure to eliminate the risk of material shedding and meet the application scenarios with high cleanliness requirements; the latter utilizes the wideband disturbance characteristics of the porous material structure 46 and the frequency selective amplification characteristics of the resonant cavity 44 to achieve a wider start-up pressure window and stronger resistance to gas supply fluctuations, which can adapt to different application scenarios and performance requirements.

[0089] 4. The vibration excitation structure of this application only involves machining the resonant cavity 44 and the air supply throttling hole 41 on the air float surface of the thrust bearing. It does not require modification of the original structure of the rotor 72, radial bearing 60, etc., nor does it require change of the original speed characteristics and radial accuracy of the air float spindle. The processing and manufacturing cost is low, and it is easy to promote and apply it to existing air float spindle products.

[0090] 5. This application improves the axial air film stiffness and the natural frequency of the air-bearing spindle by reducing the air film gap, so that the natural frequency of the air-bearing spindle matches the excitation frequency generated by the resonant cavity 44, thereby achieving resonance enhancement and improving the stability and consistency of the vibration amplitude. The flatness error of the gap disk 90 is no greater than 1μm and the parallelism error is no greater than 2μm, which can ensure that the air film gap is uniformly distributed along the circumference and ensure that the excitation force is uniformly applied to the rotor disk 30.

[0091] This application also provides a circuit board processing apparatus, including a machine base, a drive mechanism, and an air-bearing spindle according to any of the above embodiments. The drive mechanism is disposed on the machine base and connected to the air-bearing spindle. The drive mechanism is used to drive the air-bearing spindle to move as a whole, for example, to drive the air-bearing spindle to move as a whole in the vertical and horizontal directions, so as to process the circuit board on the machine base. The circuit board processing apparatus can be a circuit board drilling machine, a grinding machine, a milling machine, or a carving machine, etc.

[0092] The circuit board processing equipment of this application has all the beneficial effects of the aforementioned air-bearing spindle because it adopts the air-bearing spindle.

[0093] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An air-bearing main shaft, characterized in that, The system includes a shaft core, a first thrust bearing, and a second thrust bearing. A rotor disk is mounted on the shaft core. The first and second thrust bearings are located on opposite sides of the rotor disk along the axial direction. Gas film gaps are formed between the first and second thrust bearings and between the first and second thrust bearings and the rotor disk. Both the first and second thrust bearings are equipped with gas supply throttling structures for supplying gas to the corresponding gas film gaps. The first and / or second thrust bearings are equipped with resonant cavities, each including a cavity body and a constricted section. One end of the constricted section communicates with the cavity body, and the other end communicates with the corresponding gas film gap. The cross-sectional area of ​​the constricted section is smaller than that of the cavity body. The air-bearing main shaft also includes a housing. The shaft core is rotatably mounted through the housing. The rotor disk, the first thrust bearing, and the second thrust bearing are all mounted on the housing. The housing is equipped with a gas supply channel that communicates with each of the gas supply throttling structures. The resonant cavity can be configured to generate Helmholtz resonance under the action of gas to form periodic pressure pulsations. The periodic pressure pulsations are output to the corresponding gas film gap through the constricted section, causing the gas pressure in the gas film gap to change periodically, thereby driving the rotor disk to drive the shaft core to reciprocate along the axial direction.

2. The air-bearing spindle as described in claim 1, characterized in that, The constricted section is coaxially arranged with the cavity.

3. The air-bearing spindle as described in claim 1, characterized in that, The necked section is a single through hole or a micropore array; wherein, when the necked section is a micropore array, the micropore array includes a plurality of spaced through holes, and the two ends of each through hole are respectively connected to the cavity and the air film gap.

4. The air-bearing spindle as described in claim 1, characterized in that, The gas supply throttling structure includes a gas supply throttling orifice, which has an inlet end and an outlet end. The inlet end is connected to the gas supply channel, and the outlet end is connected to the corresponding cavity.

5. The air-bearing main shaft as described in claim 1, characterized in that, The air supply throttling structure includes an air supply throttling orifice, which has an inlet end and an outlet end. The inlet end is connected to the air supply channel, and the outlet end is connected to the corresponding air film gap and is located adjacent to the constriction section.

6. The air-bearing spindle as described in claim 1, characterized in that, The first thrust bearing and / or the second thrust bearing includes a bearing body and a porous material structure. The porous material structure is disposed on the end face of the bearing body facing the rotor disk. The porous material structure has multiple micropores inside. The resonant cavity is disposed on the bearing body and / or the porous material structure.

7. The air-bearing main shaft as described in claim 6, characterized in that, The porous material structure extends axially in a ring shape and covers at least a portion of the end face of the bearing body facing the rotor disk; or, the porous material structure comprises a plurality of circumferentially distributed arc-shaped segments.

8. The air-bearing main shaft as described in claim 6, characterized in that, The micropores of the porous material structure constitute at least a portion of the gas supply throttling structure, and the micropores are used to supply gas to the gas film gap.

9. The air-bearing main shaft as described in claim 8, characterized in that, The gas supply throttling structure includes a gas supply throttling orifice, which is disposed through the porous material structure. The orifice has a larger diameter than the micropore. The gas supply throttling orifice and the micropore are used to supply gas to the gas film gap simultaneously.

10. The air-bearing main shaft as described in claim 9, characterized in that, The resonant cavity is disposed on the porous material structure, and the cavity is connected to at least one of the air supply throttling holes and at least one of the micropores.

11. The air-bearing spindle as described in any one of claims 1-10, characterized in that, The resonant frequency f of the resonant cavity satisfies the following relationship: Where c is the speed of sound, A is the cross-sectional area of ​​the constricted section, V is the volume of the cavity, and L is the axial length of the constricted section; by setting at least one of A, V, and L, the resonant frequency of the resonant cavity is matched with the frequency of the axial reciprocating motion of the shaft core.

12. A circuit board processing equipment, characterized in that, Includes the air-bearing spindle as described in any one of claims 1-11.

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