Ultra-precision air-floating motorized spindle

Abstract

The application provides an ultra-precision air-floating electric spindle, which comprises a shell, a rotating shaft, an air-floating bearing, a driving motor and a broach mechanism, a spiral groove is arranged in the shell to form a cooling water channel, an axial air hole is formed in the bearing, and the strength of the bearing, the cooling of the spindle and the air supply of the bearing are cooperatively controlled; the thrust bearing is designed in a tapered annular slit, compressed gas is branched to the radial bearing after passing through the air path of the thrust bearing, the gas utilization rate is improved, the broach mechanism is integrated with a displacement sensor and an independent disc spring system, and the broach action is accurately controlled through air pressure. The working stability and machining precision of the spindle are significantly improved through the optimization of the structural design, the improvement of the cooling efficiency, the improvement of the gas utilization rate and the integration of the sensor; the reciprocating spiral groove is introduced to enhance the turbulent effect of the cooling water channel, the tapered annular slit is designed to increase the gas film stiffness, and the displacement sensor and the rotating speed sensor are integrated to realize the accurate monitoring of the running state of the spindle.

Description

Technical Field

[0001] This invention relates to the field of ultra-precision machining equipment technology, specifically to an ultra-precision air-bearing electric spindle. Background Technology

[0002] An air-bearing spindle refers to a spindle that uses gas (usually air, but other gases can also be used) as a lubricating medium. During operation, pure air at a certain pressure is introduced into the bearing section to form an air film gap between the shaft and the bearing, thereby achieving the effect of generating support force without direct contact. This design can reduce mechanical wear, improve machining accuracy, and is suitable for high-precision machining fields.

[0003] The shortcomings of existing technology:

[0004] 1. Poor strength: Traditional air-bearing spindles may lack strength due to structural design reasons, and may undergo slight deformation under heavy loads, affecting the machining accuracy of the workpiece and limiting its application range.

[0005] 2. Low gas utilization rate: Most air-bearing spindles use radial bearings and thrust bearings to supply gas simultaneously, which does not make full use of compressed gas, resulting in high gas consumption.

[0006] 3. Poor heat dissipation: Some air-bearing spindles have poor heat dissipation, which may lead to thermal deformation and thus affect machining accuracy.

[0007] 4. Wear and tear after long-term use: Although the wear of air-bearing spindles is less than that of mechanical spindles, wear may still occur on the shaft and journal after long-term operation, which will reduce the accuracy and stability of the spindle.

[0008] 5. Lack of precise monitoring: Traditional air-bearing spindles are usually not equipped with sensors, making it impossible to accurately detect the spindle's operating status, including but not limited to parameters such as speed and displacement. This is not conducive to real-time adjustment and optimization of the machining process.

[0009] Therefore, existing technologies have shortcomings and need further improvement. Summary of the Invention

[0010] To address the problems existing in the prior art, this invention provides an ultra-precision air-bearing electric spindle.

[0011] To achieve the above objectives, the specific solution of the present invention is as follows:

[0012] This invention provides an ultra-precision air-bearing electric spindle, comprising:

[0013] Front cover, rear cover, flange, housing, shaft, front radial bearing, rear radial bearing, front thrust bearing, rear thrust bearing, drive motor, and cutter mechanism;

[0014] The front radial bearing, front thrust bearing, rear thrust bearing, rear radial bearing, drive motor, and cylinder are sequentially arranged inside the housing.

[0015] The front end cover and the rear end cover are respectively fixed to the front end of the front radial bearing and the rear end of the cylinder, forming a closed cavity;

[0016] The rotating shaft passes through the front radial bearing, front thrust bearing, rear thrust bearing, rear radial bearing, drive motor, and cylinder inside the housing, and extends from the front end to the front end cover for mounting the cutting tool, and the rear end is coaxially and fixedly connected to the rotor of the drive motor.

[0017] The rotating shaft is also fixedly equipped with a thrust disk, and the front thrust bearing and the rear thrust bearing are respectively located on the front and rear end faces of the thrust disk of the rotating shaft.

[0018] The drawbar mechanism includes a cylinder, a push rod, a piston, a disc spring, a drawbar, and a handle;

[0019] The push rod is installed inside the rotating shaft. The front end of the push rod is connected to the pull cutter, and the rear end of the push rod is equipped with a piston. The piston is installed in the pneumatic chamber of the cylinder. The disc spring is installed on the pull cutter, and the handle is installed in front of the pull cutter.

[0020] The housing is provided with an air passage, and gas forms an air film between the thrust plate and the front thrust bearing and the rear thrust bearing, and between the rotating shaft and the front radial bearing and the rear radial bearing.

[0021] Furthermore, the rear end cover is integrated with a cooling water inlet, a cooling water outlet, an air inlet, a motor wiring port, a sensor wiring port, and a cutter pneumatic control interface.

[0022] Furthermore, the air passages of the front radial bearing and the rear radial bearing include a number of axially spaced air holes evenly distributed around the circumference, and the inlet end of the air passage is connected to the air inlet of the rear end cover.

[0023] Furthermore, both the front thrust bearing and the rear thrust bearing are constructed by bolting together a first annular component and a second annular component, forming an annular slit between the first annular component and the second annular component. The inlet gap of the annular slit is larger than the outlet gap, forming a high-pressure gas film.

[0024] Furthermore, the air inlet on the rear end cover is used to input gas. The cylinder and the housing are connected by air passages. The gas enters the housing from the cylinder and is input from the housing. It flows through the gradually narrowing annular slits of the front thrust bearing and the rear thrust bearing in sequence to form a high-pressure gas film. Then it is diverted to the axial air passages of the front radial bearing and the rear radial bearing to complete the secondary utilization of the gas and improve the gas utilization rate.

[0025] Furthermore, the inner wall of the pneumatic chamber of the cylinder of the cutter mechanism is provided with a displacement sensor, which is used to detect the axial displacement of the push rod by detecting the movement of the piston;

[0026] An encoder is also installed on the rotating shaft. The encoder rotates with the rotating shaft. A speed sensor is also installed on the inner wall of the cylinder at a position corresponding to the encoder, which is used to monitor the rotation speed of the rotating shaft in real time.

[0027] Furthermore, the pneumatic control interface of the cutter is connected to the pneumatic chamber of the cylinder. Compressed gas is input into the pneumatic chamber of the cylinder to push the piston and push rod forward, overcoming the preload of the disc spring to release the cutter. After the gas is released, the disc spring elastically resets to complete the tightening of the cutter.

[0028] Furthermore, the outer peripheral surfaces of the front radial bearing, the rear radial bearing, and the cylinder are provided with reciprocating spiral grooves to form a cooling water channel. The cooling water inlet and the cooling water outlet are connected to the cooling water channel. Water flows in from the cooling water inlet and out from the cooling water outlet to form turbulence, directly contacting the heat-generating area and improving heat exchange efficiency.

[0029] Furthermore, the drive motor adopts an embedded layout, with the stator fixed to the inner wall of the cylinder and the rotor sleeved on the rear end of the rotating shaft to directly drive the rotating shaft to rotate, without transmission chain error.

[0030] Furthermore, the motor wiring port is electrically connected to the stator of the drive motor;

[0031] The sensor wiring port is electrically connected to the displacement sensor and the speed sensor.

[0032] The technical solution of this invention has the following beneficial effects:

[0033] 1. Enhanced structural strength and rigidity: By setting axial air holes in the front and rear radial bearings, the overall rigidity and resistance to deformation of the spindle are improved, thereby enhancing working stability and machining accuracy.

[0034] 2. Significantly Improved Thermal Stability: The cooling water channels formed by the reciprocating spiral grooves directly contact the heat-generating areas, creating a turbulent heat dissipation mechanism that greatly improves cooling efficiency. This design effectively suppresses thermal deformation under high-speed rotation, ensuring machining accuracy.

[0035] 3. Improve gas utilization: Compressed gas is preferentially supplied to the thrust bearing, and its exhaust gas is reused in the radial bearing through the diversion channel, which realizes efficient gas utilization and reduces energy consumption and operating costs.

[0036] 4. Gradual contraction air film design: The thrust bearing adopts a gradually contracting annular slit with an inlet clearance larger than the outlet clearance, which enhances the air film stiffness and provides higher load-bearing capacity under the same air supply pressure.

[0037] 5. High-precision tool changing operation: The tool changing mechanism integrates a displacement sensor and a disc spring system, which can realize high-precision and fast-response tool changing action and ensure repeatability.

[0038] 6. Precise speed control: The speed sensor is embedded inside the cylinder and directly detects the signal at the end of the shaft, providing accurate speed monitoring, reducing speed fluctuations, and shortening dynamic response time.

[0039] 7. Compact and reliable design: The drive motor adopts an embedded layout, with the stator fixed to the inner wall of the cylinder, which reduces the axial space ratio and makes the whole device more compact; at the same time, multiple interfaces are centrally arranged on the rear cover, simplifying external pipeline connections and improving the reliability of the equipment.

[0040] 8. Self-cleaning and anti-contamination performance: The continuous gas flow within the air film gap helps prevent contaminants such as cutting fluid from entering the bearing, extending the service life of the equipment and reducing the failure rate. Attached Figure Description

[0041] Figure 1 This is a cross-sectional view of the present invention;

[0042] Figure 2 This is a perspective view of the thrust bearing of the present invention.

[0043] Figure 3 This is a perspective view of the present invention.

[0044] Figure 4 This is a perspective view of the front radial bearing of the present invention.

[0045] Figure 5 This is a cross-sectional view of the waterway of the present invention.

[0046] Figure 6 This is a perspective view of the present invention after removing the outer casing and flange.

[0047] Figure 7 This is a cross-sectional view of the gas path of the present invention.

[0048] In the picture:

[0049] 1. Front cover; 2. Rear cover; 3. Flange; 4. Housing; 5. Shaft; 6. Front radial bearing; 7. Rear radial bearing; 8. Front thrust bearing; 81. First annular component; 82. Second annular component; 83. Bolt; 84. Annular slit; 9. Rear thrust bearing; 10. Drive motor; 101. Stator; 102. Rotor; 11. Cutting tool mechanism; 111. Cylinder; 112. Push rod; 113. Piston; 114. Disc spring; 115. Cutting tool; 116. Tool holder; 12. Displacement sensor; 13. Speed ​​sensor; 14. Air passage; 141. Axial air port; 15. Air inlet; 16. Cooling water passage; 17. Cooling water inlet; 18. Cooling water outlet; 20. Motor wiring port; 21. Sensor port; 22. Cutting tool pneumatic control interface; 23. Diverter channel; 24. Thrust plate; 25. Encoder. Detailed Implementation

[0050] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, and not all of them.

[0051] Combination Figures 1-7 As shown, the present invention provides an ultra-precision air-bearing electric spindle, comprising:

[0052] 1. Front cover, 2. Rear cover, 3. Flange, 4. Housing, 5. Shaft, 6. Front radial bearing, 7. Rear radial bearing, 8. Front thrust bearing, 9. Rear thrust bearing, 10. Drive motor, 11. Cutting mechanism.

[0053] The front radial bearing 6, the front thrust bearing 8, the rear thrust bearing 9, the rear radial bearing 7, the drive motor 10, and the cylinder 111 are sequentially arranged inside the housing 4.

[0054] The front cover 1 and the rear cover 2 are respectively fixed to the front end of the front radial bearing 6 and the rear end of the cylinder 111, forming a closed cavity;

[0055] The rotating shaft 5 passes through the front radial bearing 6, front thrust bearing 8, rear thrust bearing 9, rear radial bearing 7, drive motor 10, and cylinder 111 inside the housing 4, and the front end extends out to the front end cover 1 for installing the cutting tool, and the rear end is coaxially and fixedly connected to the rotor 102 of the drive motor 10.

[0056] The rotating shaft 5 is also fixedly provided with a thrust disk 24, and the front thrust bearing 8 and the rear thrust bearing 9 are respectively provided on the front and rear end faces of the thrust disk 24 of the rotating shaft 5.

[0057] The drawbar mechanism 11 includes a cylinder 111, a push rod 112, a piston 113, a disc spring 114, a drawbar 115, and a handle 116;

[0058] The push rod 112 is installed inside the rotating shaft 5. The front end of the push rod 112 is connected to the pull cutter 115. The rear end of the push rod 112 is provided with a piston 113. The piston 113 is installed in the pneumatic chamber of the cylinder 111. The disc spring 114 is installed on the pull cutter 115. The handle 116 is installed in front of the pull cutter 115.

[0059] The housing 4 is provided with an air passage 14, and gas forms an air film between the thrust plate 24 and the front thrust bearing 8 and the rear thrust bearing 9, and between the rotating shaft 5 and the front radial bearing 6 and the rear radial bearing 7.

[0060] The rear cover 2 is integrated with a cooling water inlet 17, a cooling water outlet 18, an air inlet 15, a motor wiring port 20, a sensor wiring port, and a pneumatic control interface for the pull knife 115.

[0061] The air passages 14 of the front radial bearing 6 and the rear radial bearing 7 include a plurality of axial air holes 141 evenly distributed in the circumference, and the inlet end of the air passage 14 is connected to the air inlet 15 of the rear end cover 2.

[0062] Both the front thrust bearing 8 and the rear thrust bearing 9 are formed by connecting the first annular component 81 and the second annular component 82 with bolts 83. An annular slit 84 is formed between the first annular component 81 and the second annular component 82. The inlet gap of the annular slit 84 is larger than the outlet gap, forming a high-pressure gas film.

[0063] The air inlet 15 on the rear end cover 2 is used to input gas. The cylinder 111 and the housing 4 are connected by an air passage 14. The gas enters the housing 4 from the cylinder 111 and flows through the gradually narrowing annular slit 84 of the front thrust bearing 8 and the rear thrust bearing 9 in sequence to form a high-pressure gas film. Then it is diverted to the axial air passage 14 of the front radial bearing 6 and the rear radial bearing 7 to complete the secondary utilization of the gas and improve the gas utilization rate.

[0064] The inner wall of the pneumatic cavity of the cylinder 111 of the drawbar mechanism 11 is provided with a displacement sensor 12, which is used to detect the axial displacement of the push rod 112 by detecting the movement of the piston 113.

[0065] An encoder 25 is also provided on the rotating shaft 5. The encoder 25 rotates together with the rotating shaft 5. A speed sensor 13 is also provided on the inner wall of the cylinder 111 at a position corresponding to the encoder 25, for real-time monitoring of the rotation speed of the rotating shaft 5.

[0066] The pneumatic control interface of the pull cutter 115 is connected to the pneumatic chamber of the cylinder 111. Compressed gas is input into the pneumatic chamber of the cylinder 111, pushing the piston 113 and push rod 112 forward to overcome the preload of the disc spring 114 and realize the release of the pull cutter 115. After the gas is released, the disc spring 114 elastically resets to complete the tightening of the cutter.

[0067] The outer peripheral surfaces of the front radial bearing 6, the rear radial bearing 7, and the cylinder 111 are provided with reciprocating spiral grooves to form a cooling water passage 16. The cooling water inlet 17 and the cooling water outlet 18 are connected to the cooling water passage 16. Water flows in from the cooling water inlet 17 and out from the cooling water outlet 18 to form turbulence, directly contacting the heat-generating area and improving heat exchange efficiency.

[0068] The drive motor 10 adopts an embedded layout, with the stator 101 fixed to the inner wall of the cylinder 111 and the rotor 102 sleeved on the rear end of the rotating shaft 5 to directly drive the rotating shaft 5 to rotate, without transmission chain error.

[0069] The motor wiring port 20 is electrically connected to the stator 101 of the drive motor 10;

[0070] The sensor wiring port is electrically connected to the displacement sensor 12 and the speed sensor 13.

[0071] The working principle of this invention is as follows:

[0072] 1. Suspension and load-bearing of air bearings

[0073] Axial limiting: Compressed gas enters the tapered annular slit 84 of the front thrust bearing 8 and the rear thrust bearing 9 through the air inlet 15 of the rear end cover 2. Due to the design that the inlet gap is larger than the outlet gap, this not only reduces flow resistance but also improves the gas film stiffness, achieving bidirectional axial limiting of the rotating shaft 5.

[0074] 2. Radial Suspension: The gas exiting the thrust bearing then flows into the front radial bearing 6 and the rear radial bearing 7, forming a high-pressure gas film in the gap between these bearings and the rotating shaft 5. This allows the rotating shaft 5 to maintain a radially centered suspended state, avoiding wear caused by direct contact and improving rotational accuracy.

[0075] 3. Cooling and Thermal Management

[0076] Spiral turbulent cooling: Cooling water enters the reciprocating spiral grooves on the outer surface of the front radial bearing 6, the rear radial bearing 7, and the cylinder 111 through the cooling water inlet 17. The water flow path is designed as an alternating turbulent flow pattern, ensuring high heat exchange efficiency. Finally, it is discharged through the cooling water outlet 18, effectively absorbing the bearing air friction heat and the heat generated by the motor.

[0077] 4. Drive and tool change control

[0078] Motor drive: The stator 101 of the drive motor 10 embedded in the cylinder 111 is fixed, while its rotor 102 is directly connected to the rotating shaft 5, with no transmission chain error, ensuring stability during high-speed rotation.

[0079] 5. Pneumatic Tool Changer: When a tool change is required, compressed gas is input into the cylinder 111 through the pneumatic control interface of the drawbar 115, pushing the piston 113 and push rod 112 forward to overcome the preload of the disc spring 114 and achieve the tool loosening action. After the tool change is completed, the compressed gas is released, and the disc spring 114 elastically returns to its original position to tighten the tool.

[0080] 6. Monitoring and Feedback

[0081] Real-time monitoring: The displacement sensor 12 is installed on the inner wall of the cylinder 111 to detect the axial displacement of the push rod 112 and ensure precise control of the tool changing process; at the same time, the speed sensor 13 is also installed on the inner wall of the cylinder 111 to monitor the encoder 25 signal at the tail end of the rotating shaft 5 in real time, providing accurate speed information, which helps to dynamically adjust and optimize the machining process.

[0082] In summary, this invention, through a series of innovative designs, such as the air path 14 system, cooling water path 16, tapered air film design, and integrated sensing technology, significantly improves the working stability and machining accuracy of the air-bearing electric spindle, solving problems such as low cooling efficiency, low gas utilization, and insufficient tool changing accuracy inherent in traditional air-bearing spindles. Furthermore, the compact and reliable design greatly reduces the complexity of external piping, enhancing the overall performance of the equipment.

[0083] Example 1:

[0084] This embodiment provides an air-bearing electric spindle for ultra-precision machining, the specific structure and parameters of which are as follows:

[0085] Housing 4 and rotating shaft 5

[0086] Housing 4: Made of 630 stainless steel, with an outer diameter of 200mm and an axial length of 400mm. It has a stepped hole structure inside for mounting bearings and drive motor 10.

[0087] The rotating shaft 5 is made of FS136 steel with an outer diameter of 60mm. The front end extends 100mm beyond the front end cover 1 for mounting the HSK-63 tool holder 116. The rear end is coaxially fixed to the rotor 102 of the drive motor 10 via a heat-fitting process. The surface of the rotating shaft 5 is polished to Ra≤0.05μm.

[0088] bearing system

[0089] Front radial bearing 6 and rear radial bearing 7: Made of stainless steel, with an inner diameter of 60.02 mm and an outer diameter of 80 mm. They have 24 axially distributed pores 141, each with a diameter of 0.5 mm and a pore spacing of 15°, resulting in an air film gap of 8 μm. Front / rear thrust bearing 9: Connected by an annular component via M6 bolts 83, made of cemented carbide. The annular slit 84 has an inlet gap of 15 μm and an outlet gap of 5 μm, forming a gradually narrowing air film channel.

[0090] Drive motor 10

[0091] Stator 101: Adopts a slotless winding design, fixed to the inner wall of cylinder 111, rated power 10kW, maximum speed 60,000rpm. Rotor 102: Permanent magnets are embedded in the rear end of the rotating shaft 5, directly driving the rotating shaft 5 through electromagnetic coupling, with no transmission chain error and speed fluctuation rate <0.01%.

[0092] Broaching mechanism 11

[0093] Push rod 112: Made of titanium alloy, 20mm in diameter, passing through the inside of the rotating shaft 5, with the front end connected to the pull cutter 115, and the rear end linked to the pneumatic chamber of the cylinder 111 via the piston 113. Disc spring 114: Preload force is 500N, elastic stroke is 2mm, and tool change repeatability is ±1μm.

[0094] Cooling and airflow system 14

[0095] Cooling water passage 16: Reciprocating spiral grooves (10mm pitch, 3mm depth) are machined on the outer surfaces of the front / rear radial bearings 7 and cylinder 111. The cooling water flow rate is 5L / min, the inlet water temperature is 25℃, and the outlet water temperature is ≤35℃. Air passage 14: Compressed air (0.6MPa) is input from the air inlet 15 of the rear end cover 2. The gas is diverted to the radial bearing after passing through the gradually narrowing slit of the thrust bearing, improving the gas utilization rate by 35%.

[0096] Sensor system

[0097] Displacement sensor 12: A magnetostrictive sensor with a resolution of 0.1 μm, integrated into the inner wall of cylinder 111, to detect the displacement of push rod 112 in real time. Speed ​​sensor 13: A Hall effect sensor that detects the signal from encoder 25 at the tail end of shaft 5, with a sampling frequency of 10 kHz and an accuracy of ±5 rpm.

[0098] Working principle and operating procedures

[0099] Step 1: Air bearing start-up and levitation

[0100] Compressed air is input through the inlet 15 of the rear cover 2 and flows through the tapering annular slit 84 between the front thrust bearing 8 and the rear thrust bearing 9. Because the inlet gap is larger than the outlet gap, the gas velocity increases, forming a high-pressure gas film that drives the thrust disc 24 of the rotating shaft 5 into bidirectional suspension, achieving an axial load capacity of 2000N. The exhaust from the thrust bearings enters the gap between the front and rear radial bearings (6, 7) and the rotating shaft 5 through the diversion channel 23, forming a radial gas film and achieving frictionless suspension.

[0101] Step 2: Start-up and processing of drive motor 10

[0102] After the drive motor 10 is powered on, the stator winding 101 generates a rotating magnetic field, which drives the rotor 102 and the shaft 5 to rotate at a high speed of 60,000 rpm, directly driving the tool to perform ultra-precision cutting. The speed sensor 13 monitors the speed of the shaft 5 in real time and feeds it back to the control system to dynamically adjust the motor input frequency to ensure that the speed fluctuation rate is <0.01%.

[0103] Step 3: Cooling and Thermal Management

[0104] Cooling water enters the spiral groove from the cooling water inlet 17 of the rear cover 2, forming turbulent flow with alternating directions, directly absorbing the frictional heat of the bearing air film and the heat generated by the motor. The outlet water temperature is ≤35℃, and the temperature rise is controlled within 10℃.

[0105] Step 4: Tool Change Operation

[0106] Release the tool: Compressed gas is input into the pneumatic chamber of cylinder 111 through the pneumatic control interface of the drawbar 115, pushing the piston 113 and push rod 112 forward by 2mm, overcoming the preload of disc spring 114, and the drawbar 115 releases the tool holder 116. Displacement sensor 12 detects displacement deviation in real time. Tighten the tool: After the gas is released, disc spring 114 elastically returns to its original position, driving push rod 112 back to its original position, and the drawbar 115 locks the tool holder 116. The tool change action takes 0.1 seconds.

[0107] Step 5: Condition Monitoring and Maintenance

[0108] Sensor data is transmitted to the host computer via sensor port 21 on the rear cover 2, displaying the spindle's operating status in real time. A continuous supply of clean air through the air film prevents cutting fluid from entering the bearing clearances, extending the maintenance cycle to 2000 hours.

[0109] Performance verification and results

[0110] Machining Accuracy: At 60,000 rpm, the spindle radial runout is ≤0.1μm and axial runout is ≤0.05μm, meeting the requirements for optical lens processing. Energy Consumption Optimization: Gas reuse design reduces compressed air consumption by 35% and overall energy consumption by 25%. Heat Dissipation Efficiency: The 16-channel turbulent design of the cooling water improves heat exchange efficiency by 40%, keeping the spindle temperature rise below 10℃. Tool Changing Reliability: Tool changing repeatability is ±1μm, with a response time of 0.1 seconds, suitable for high-precision multi-process machining.

[0111] Summarize

[0112] This embodiment achieves frictionless high-speed rotation of the spindle, precise tool changing, real-time monitoring, and low-energy operation through high-rigidity air bearings, staged air supply, turbulent cooling, intelligent sensing, and compact integrated design. It solves the technical bottlenecks of traditional air-bearing spindles in terms of rigidity, heat dissipation, precision, and intelligent control, and is suitable for ultra-precision machining fields such as semiconductors and optical components.

[0113] The above description is only a preferred embodiment of the present invention and does not limit the scope of the invention. All equivalent structural transformations made under the inventive concept of the present invention using the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. An ultra-precision air-bearing electric spindle, characterized in that, include: Front cover, rear cover, flange, housing, shaft, front radial bearing, rear radial bearing, front thrust bearing, rear thrust bearing, drive motor, and cutter mechanism; The front radial bearing, front thrust bearing, rear thrust bearing, rear radial bearing, drive motor, and cylinder are sequentially arranged inside the housing. The front end cover and the rear end cover are respectively fixed to the front end of the front radial bearing and the rear end of the cylinder, forming a closed cavity; The rotating shaft passes through the front radial bearing, front thrust bearing, rear thrust bearing, rear radial bearing, drive motor, and cylinder inside the housing, and extends from the front end to the front end cover for mounting the cutting tool, and the rear end is coaxially and fixedly connected to the rotor of the drive motor. The rotating shaft is also fixedly equipped with a thrust disk, and the front thrust bearing and the rear thrust bearing are respectively located on the front and rear end faces of the thrust disk of the rotating shaft. The drawbar mechanism includes a cylinder, a push rod, a piston, a disc spring, a drawbar, and a handle; The push rod is installed inside the rotating shaft. The front end of the push rod is connected to the pull cutter, and the rear end of the push rod is equipped with a piston. The piston is installed in the pneumatic chamber of the cylinder. The disc spring is installed on the pull cutter, and the handle is installed in front of the pull cutter. The housing is provided with an air passage, and gas forms an air film between the thrust plate and the front thrust bearing and the rear thrust bearing, and between the rotating shaft and the front radial bearing and the rear radial bearing. Both the front thrust bearing and the rear thrust bearing are composed of a first annular component and a second annular component connected by bolts. An annular slit is formed between the first annular component and the second annular component. The inlet gap of the annular slit is larger than the outlet gap, forming a high-pressure gas film.

2. The ultra-precision air-bearing electric spindle according to claim 1, characterized in that: The rear end cover is integrated with a cooling water inlet, a cooling water outlet, an air inlet, a motor wiring port, a sensor wiring port, and a knife pneumatic control interface.

3. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The air passages of the front radial bearing and the rear radial bearing include a number of axially spaced air holes evenly distributed around the circumference, and the inlet end of the air passage is connected to the air inlet of the rear end cover.

4. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The air inlet on the rear end cover is used to input gas. The cylinder and the housing are connected by air passages. The gas enters the housing from the cylinder and is input from the housing. It flows through the gradually narrowing annular slits of the front thrust bearing and the rear thrust bearing in sequence to form a high-pressure gas film. Then it is diverted to the axial air passages of the front radial bearing and the rear radial bearing to complete the secondary utilization of the gas and improve the gas utilization rate.

5. The ultra-precision air-bearing electric spindle according to claim 1, characterized in that: The inner wall of the pneumatic chamber of the cylinder of the cutter mechanism is equipped with a displacement sensor, which is used to detect the axial displacement of the push rod by detecting the movement of the piston. An encoder is also installed on the rotating shaft. The encoder rotates with the rotating shaft. A speed sensor is also installed on the inner wall of the cylinder at a position corresponding to the encoder, which is used to monitor the rotation speed of the rotating shaft in real time.

6. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The pneumatic control interface of the cutter is connected to the pneumatic chamber of the cylinder. Compressed gas is input into the pneumatic chamber of the cylinder, pushing the piston and push rod forward to overcome the preload of the disc spring and release the cutter. After the gas is released, the disc spring elastically resets to complete the tightening of the cutter.

7. The ultra-precision air-bearing electric spindle according to claim 1, characterized in that: The outer circumferential surfaces of the front radial bearing, rear radial bearing, and cylinder are provided with reciprocating spiral grooves to form a cooling water channel. The cooling water inlet and cooling water outlet are connected to the cooling water channel. Water flows in from the cooling water inlet and out from the cooling water outlet to form turbulence, directly contacting the heat-generating area and improving heat exchange efficiency.

8. The ultra-precision air-bearing electric spindle according to claim 1, characterized in that: The drive motor adopts an embedded layout, with the stator fixed to the inner wall of the cylinder and the rotor sleeved on the rear end of the rotating shaft to directly drive the rotating shaft to rotate, without transmission chain error.

9. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The motor wiring port is electrically connected to the stator of the drive motor; The sensor wiring port is electrically connected to the displacement sensor and the speed sensor.

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