Ultra-precise air-floating electric spindle

Abstract

The invention provides an ultra-precise air flotation electric spindle which comprises a shell, a rotating shaft, an air flotation bearing, a driving motor and a broach mechanism, a spiral groove is formed in the shell to form a cooling water way, an axial air hole is formed in the bearing, and cooperative control over the bearing strength, spindle cooling and bearing air supply is achieved; the thrust bearing adopts a tapered annular slit design, compressed gas is shunted to the radial bearing after passing through a gas 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 tool changing action is accurately controlled through air pressure. By optimizing the structural design, improving the cooling efficiency, improving the gas utilization rate, integrating the sensor and the like, the working stability and the machining precision of the main shaft are remarkably improved; a reciprocating spiral groove is introduced to enhance the turbulence effect of a cooling water channel, a gradually-shrunk annular slit is designed to increase the rigidity of an air film, and a displacement sensor and a rotating speed sensor are integrated to achieve accurate monitoring of the running state of the main shaft.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-precision machining equipment, and particularly to an ultra-precision air-bearing motor spindle. Background Art

[0002] An air-bearing spindle refers to a spindle that uses gas (usually air, but other gases can also be used) as a lubricant medium; during operation, by introducing pure air with a certain pressure into the bearing part, an air film gap is formed between the rotating shaft and the bearing, thereby achieving the effect of non-direct contact and generating a supporting force; this design can reduce mechanical wear, improve machining accuracy, and is suitable for the field of high-precision machining.

[0003] Deficiencies of the prior art: 1. Poor strength: Traditional air-bearing spindles may have insufficient strength due to structural design reasons, and may undergo minor deformations under large loads, affecting the machining accuracy of workpieces and limiting their application scope.

[0004] 2. Low gas utilization rate: Most air-bearing spindles supply gas to the radial bearing and thrust bearing separately, without making full use of the compressed gas, resulting in a relatively high gas consumption.

[0005] 3. Poor heat dissipation effect: Some air-bearing spindles have problems with poor heat dissipation, which may lead to thermal deformation and further affect machining accuracy.

[0006] 4. Wear problems after long-term use: Although the wear of air-bearing spindles is relatively small compared to mechanical wear, after long-term operation, wear may still occur on the rotating shaft and journal, which will reduce the accuracy and stability of the spindle.

[0007] 5. Lack of precise monitoring: Traditional air-bearing spindles usually do not have sensors installed, and cannot accurately detect the operating state of the spindle, including but not limited to parameters such as rotational speed and displacement, which is not conducive to real-time adjustment and optimization of the machining process.

[0008] Therefore, the prior art has deficiencies and needs further improvement. Summary of the Invention

[0009] In view of the problems existing in the prior art, the present invention provides an ultra-precision air-bearing motor spindle.

[0010] To achieve the above object, the specific solution of the present invention is as follows: The present invention provides an ultra-precision air-bearing motor spindle, comprising: a front end cover, a rear end cover, a flange, a housing, a rotating shaft, a front radial bearing, a rear radial bearing, a front thrust bearing, a rear thrust bearing, a drive motor, and a tool puller mechanism; The front radial bearing, front thrust bearing, rear thrust bearing, rear radial bearing, drive motor, and cylinder barrel 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 barrel to form 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 barrel inside the housing, and extends out of the front end cover at the front end for installing a tool, and is coaxially fixedly connected to the rotor of the drive motor at the rear end; A thrust disk is also fixedly arranged on the rotating shaft, and the front thrust bearing and the rear thrust bearing are respectively arranged on the front and rear end faces of the thrust disk of the rotating shaft; The broaching mechanism includes a cylinder barrel, a push rod, a piston, a disc spring, a broach, and a tool holder; The push rod passes through the inside of the rotating shaft, the front end of the push rod is connected to the broach, the rear end of the push rod is provided with a piston, the piston is arranged in the pneumatic cavity of the cylinder barrel, the disc spring is arranged on the broach, and the tool holder is arranged in front of the broach; An air circuit is arranged in the housing, and air forms an air film between the thrust disk 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.

[0011] Further, the rear end cover is integrally provided with a cooling water inlet, a cooling water outlet, an air inlet, a motor wiring port, a sensor wiring port, and a broach air control interface.

[0012] Further, the air circuits of the front radial bearing and the rear radial bearing include a plurality of axially distributed axial air holes arranged circumferentially, and the inlet end of the air circuit is communicated with the air inlet of the rear end cover.

[0013] Further, 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, and 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 to form a high-pressure air film.

[0014] Further, the air inlet arranged on the rear end cover is used to input gas. An air circuit that is mutually communicated is arranged in the cylinder barrel and the housing. The gas enters the housing from the cylinder barrel, is input from the housing, and sequentially flows through the tapered annular slits of the front thrust bearing and the rear thrust bearing to form a high-pressure air film, and then is split to the axial air circuits of the front radial bearing and the rear radial bearing to complete the secondary utilization of the gas and improve the gas utilization rate.

[0015] Further, a displacement sensor is arranged on the inner wall of the pneumatic cavity of the cylinder barrel of the broaching mechanism to detect the axial displacement of the push rod by detecting the movement of the piston; An encoder is also provided on the rotating shaft, and the encoder rotates together with the rotating shaft. A rotational speed sensor is also provided at a position on the inner wall of the cylinder corresponding to the encoder for real-time monitoring of the rotational speed of the rotating shaft.

[0016] Further, the broach air control interface is communicated with the pneumatic cavity of the cylinder. Compressed gas is input into the pneumatic cavity of the cylinder to push the piston and the push rod forward, overcoming the pre-tightening force of the disc spring to realize broach tool loosening. After the gas is released, the disc spring elastically resets to complete tool tightening.

[0017] Further, reciprocating spiral grooves are provided on the outer peripheral surfaces of the front radial bearing, the rear radial bearing and the cylinder to form a cooling water path. The cooling water inlet and the cooling water outlet are communicated with the cooling water path, and water flow enters from the cooling water inlet and discharges from the cooling water outlet to form a turbulent flow, directly contacting the heat generating area to improve the heat exchange efficiency.

[0018] Further, the drive motor adopts an embedded layout, the stator is fixed on the inner wall of the cylinder, and the rotor is sleeved on the rear end of the rotating shaft to directly drive the rotating shaft to rotate without transmission chain error.

[0019] Further, 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 rotational speed sensor.

[0020] Adopting the technical solution of the present invention has the following beneficial effects: 1. Enhance structural strength and stiffness: By providing axial air holes in the front radial bearing and the rear radial bearing, the overall rigidity of the main shaft and the ability to resist deformation are improved, thereby enhancing the working stability and machining accuracy.

[0021] 2. Significantly improved thermal stability: The cooling water path formed by the reciprocating spiral grooves directly contacts the heat generating area to form a turbulent heat dissipation mechanism, greatly improving the cooling efficiency. This design effectively suppresses the thermal deformation problem under high-speed rotation and ensures the machining accuracy.

[0022] 3. Improve gas utilization rate: Compressed gas is preferentially supplied to the thrust bearing, and its exhaust gas is reused for the radial bearing through the shunt channel, realizing the efficient utilization of gas and reducing the energy consumption and operating cost.

[0023] 4. Tapered air film design: The thrust bearing adopts a tapered annular slit with an inlet gap larger than the outlet gap, enhancing the air film stiffness and providing a higher load-bearing capacity under the same supply pressure.

[0024] 5. High-precision tool change operation: The broach tool mechanism integrates a displacement sensor and a disc spring system, which can realize high-precision and fast-response tool change actions and ensure the repeat positioning accuracy.

[0025] 6. Precise speed control: The rotational speed sensor is embedded inside the cylinder barrel, directly detecting the signal at the end of the rotating shaft, providing precise rotational speed monitoring, reducing the rotational speed fluctuation rate, and shortening the dynamic response time.

[0026] 7. Compact and reliable design: The drive motor adopts an embedded layout, with the stator fixed on the inner wall of the cylinder barrel, shortening the axial space occupation ratio and making the entire device more compact; at the same time, multiple interfaces are centrally arranged on the rear end cover, simplifying the external pipeline connection and improving the reliability of the equipment.

[0027] 8. Self-cleaning and anti-pollution performance: The continuous gas flow in the air film gap helps prevent pollutants such as cutting fluid from invading the bearing, extending the service life of the equipment and reducing the failure rate. Description of the Drawings

[0028] Figure 1 is a cross-sectional view of the present invention; Figure 2 is a perspective view of the thrust bearing of the present invention Figure 3 is a perspective view of the present invention Figure 4 is a perspective view of the front radial bearing of the present invention Figure 5 is a cross-sectional view of the waterway of the present invention Figure 6 is a perspective view of the present invention after removing the outer shell sleeve and flange Figure 7 is a cross-sectional view of the gas path of the present invention In the figure: 1, front end cover; 2, rear end cover; 3, flange; 4, housing; 5, rotating shaft; 6, front radial bearing; 7, rear radial bearing; 8, front thrust bearing; 81, first annular part; 82, second annular part; 83, bolt; 84, annular slit; 9, rear thrust bearing; 10, drive motor; 101, stator; 102, rotor; 11, broaching mechanism; 111, cylinder barrel; 112, push rod; 113, piston; 114, disc spring; 115, broach; 116, tool holder; 12, displacement sensor; 13, rotational speed sensor; 14, gas path; 141, axial air hole; 15, air inlet; 16, cooling water path; 17, cooling water inlet; 18, cooling water outlet; 20, motor wiring port; 21, sensor port; 22, broach air control interface; 23, shunt channel; 24, thrust plate; 25, encoder. Detailed Embodiments

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the convenience of description, only the parts related to the present invention are shown in the drawings, rather than all of them.

[0030] As shown in Figures 1 - 7 the present invention provides an ultra-precision air-bearing motorized spindle, comprising: a front end cover 1, a rear end cover 2, a flange 3, a housing 4, a rotating shaft 5, a front radial bearing 6, a rear radial bearing 7, a front thrust bearing 8, a rear thrust bearing 9, a drive motor 10, and a tool puller mechanism 11; 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 barrel 111 are sequentially arranged inside the housing 4; The front end cover 1 and the rear end cover 2 are respectively fixed to the front end of the front radial bearing 6 and the rear end of the cylinder barrel 111 to form a closed cavity; The rotating shaft 5 penetrates through 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 barrel 111 inside the housing 4, and the front end extends out of the front end cover 1 for installing a tool, and the rear end is coaxially and fixedly connected to the rotor 102 of the drive motor 10; A thrust disk 24 is also fixedly arranged on the rotating shaft 5, and the front thrust bearing 8 and the rear thrust bearing 9 are respectively arranged on the front and rear end faces of the thrust disk 24 of the rotating shaft 5; The tool puller mechanism 11 includes a cylinder barrel 111, a push rod 112, a piston 113, a disc spring 114, a tool puller 115, and a tool holder 116; The push rod 112 penetrates through the inside of the rotating shaft 5, the front end of the push rod 112 is connected to the tool puller 115, the rear end of the push rod 112 is provided with the piston 113, the piston 113 is arranged in the pneumatic cavity of the cylinder barrel 111, the disc spring 114 is arranged on the tool puller 115, and the tool holder 116 is arranged in front of the tool puller 115; An air passage 14 is arranged in the housing 4, and an air film is formed between the thrust disk 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.

[0031] The rear end cover 2 is integrally provided 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 an air control interface for the tool puller 115.

[0032] The air passages 14 of the front radial bearing 6 and the rear radial bearing 7 include a plurality of axially distributed axial air holes 141 arranged circumferentially, and the inlet end of the air passage 14 is communicated with the air inlet 15 of the rear end cover 2.

[0033] The front thrust bearing 8 and the rear thrust bearing 9 are both composed of a first annular component 81 and a second annular component 82 connected by 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.

[0034] The air inlet 15 provided on the rear end cover 2 is used to input gas. An air passage 14 that communicates with each other is provided in the cylinder barrel 111 and the housing 4. The gas enters the housing 4 from the cylinder barrel 111, is input from the housing 4, and sequentially flows through the tapered annular slit 84 of the front thrust bearing 8 and the rear thrust bearing 9 to form a high-pressure gas film, and then is shunted to the axial air passages 14 of the front radial bearing 6 and the rear radial bearing 7, completing the secondary utilization of the gas and improving the gas utilization rate.

[0035] A displacement sensor 12 is provided on the inner wall of the pneumatic chamber of the cylinder barrel 111 of the broach mechanism 11 for detecting the axial displacement of the push rod 112 by detecting the movement of the piston 113; An encoder 25 is further provided on the rotating shaft 5. The encoder 25 rotates together with the rotating shaft 5. A rotational speed sensor 13 is also provided at a position corresponding to the encoder 25 on the inner wall of the cylinder barrel 111 for real-time monitoring of the rotational speed of the rotating shaft 5.

[0036] The air control interface of the broach 115 is communicated with the pneumatic chamber of the cylinder barrel 111. Compressed gas is input into the pneumatic chamber of the cylinder barrel 111 to push the piston 113 and the push rod 112 to move forward, overcoming the pre-tightening force of the disc spring 114 to realize the tool loosening of the broach 115. After the gas is released, the disc spring 114 elastically resets to complete the tool tightening.

[0037] Reciprocating spiral grooves are provided on the outer peripheral surfaces of the front radial bearing 6, the rear radial bearing 7, and the cylinder barrel 111 to form a cooling water passage 16. The cooling water inlet 17 and the cooling water outlet 18 are communicated with the cooling water passage 16. Water flows in from the cooling water inlet 17 and discharges from the cooling water outlet 18 to form a turbulent flow, directly contacting the heating area to improve the heat exchange efficiency.

[0038] The drive motor 10 adopts an embedded layout. The stator 101 is fixed to the inner wall of the cylinder barrel 111, and the rotor 102 is sleeved on the rear end of the rotating shaft 5 to directly drive the rotating shaft 5 to rotate without transmission chain error.

[0039] The motor wiring port 20 is electrically connected to the stator 101 of the drive motor 10; The sensor wiring port is electrically connected to the displacement sensor 12 and the rotational speed sensor 13.

[0040] The working principle of the present invention is as follows: 1. Suspension and load bearing of the aerostatic bearing Axial Limitation: 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 where the inlet gap is larger than the outlet gap, this not only reduces the flow resistance but also improves the air film stiffness, achieving bidirectional axial limitation of the rotating shaft 5.

[0041] 2. Radial Suspension: The gas coming out of the thrust bearing then flows into the front radial bearing 6 and the rear radial bearing 7, and forms a high-pressure air film in the gap between these bearings and the rotating shaft 5. This enables the rotating shaft 5 to maintain a centered suspended state radially, avoiding wear caused by direct contact and improving the rotation accuracy.

[0042] 3. Cooling and Thermal Management 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 barrel 111 through the cooling water inlet 17. The water flow path is designed in a turbulent mode with alternating spiral directions, ensuring efficient heat exchange efficiency, and finally discharged through the cooling water outlet 18, effectively absorbing the bearing air friction heat and the heat generated by the motor.

[0043] 4. Driving and Tool Changing Control Motor Driving: The stator 101 of the driving motor 10 embedded in the cylinder barrel 111 is fixed, while its rotor 102 is directly connected to the rotating shaft 5, without transmission chain error, ensuring stability during high-speed rotation.

[0044] 5. Pneumatic Tool Changing: When a tool change operation is required, compressed gas is input into the interior of the cylinder barrel 111 from the air control interface of the draw bar 115, pushing the piston 113 and the push rod 112 forward to overcome the pre-tightening force of the disc spring 114 to achieve the tool loosening action. After the tool change is completed, the compressed gas is released, and the disc spring 114 elastically resets to complete the tool tightening.

[0045] 6. Monitoring and Feedback Real-time Monitoring: The displacement sensor 12 is installed on the inner wall of the cylinder barrel 111 to detect the axial displacement of the push rod 112, ensuring precise control during the tool change process; at the same time, the rotational speed sensor 13 is also set on the inner wall of the cylinder barrel 111 to monitor the encoder 25 signal at the end of the rotating shaft 5 in real time, providing accurate rotational speed information, which helps to dynamically adjust and optimize the machining process.

[0046] In summary, through a series of innovative designs such as the air circuit 14 system, the cooling water circuit 16, the tapered air film design, and the integrated sensing technology, the present invention significantly improves the working stability and machining accuracy of the air-bearing motorized spindle, solving problems existing in traditional air-bearing spindles such as low cooling efficiency, low gas utilization rate, and insufficient tool change accuracy. In addition, the compact and reliable design also greatly reduces the complexity of external pipelines and enhances the overall performance of the equipment.

[0047] Example 1: This embodiment provides an air-bearing electric spindle for ultra-precision machining, and its specific structure and parameters are as follows: Shell 4 and shaft 5 Shell 4: Made of 630 stainless steel, with an outer diameter of 200 mm and an axial length of 400 mm, with a stepped hole structure inside for mounting bearings and drive motor 10.

[0048] Rotating shaft 5: Made of FS136, with an outer diameter of 60 mm, the front end extends 100 mm beyond the front end cover 1 and is used to install the HSK-63 tool handle 116; the rear end is coaxially fixed to the rotor 102 of the driving motor 10 through a thermal mounting process, and the surface of the rotating shaft 5 is polished to Ra≤0.05μm.

[0049] Bearing system Front radial bearing 6, rear radial bearing 7: Made of stainless steel, inner diameter 60.02mm, outer diameter 80mm, 24 axial air holes 141 evenly distributed in the circumference, hole diameter 0.5mm, air hole spacing 15°, air film gap 8μm. Front / rear thrust bearing 9: Connected by annular components through M6 bolts 83, made of cemented carbide. The entrance gap of the annular slit 84 is 15μm, and the exit gap is 5μm, forming a tapered air film channel.

[0050] Drive motor 10 Stator 101: adopts slotless winding design, fixed to the inner wall of cylinder 111, rated power 10kW, maximum speed 60,000rpm. Rotor 102: permanent magnet is embedded in the rear end of shaft 5, directly drives shaft 5 through electromagnetic coupling, no transmission chain error, speed fluctuation rate <0.01%.

[0051] Broach mechanism 11 Push rod 112: Made of titanium alloy, 20mm in diameter, penetrates the interior of rotating shaft 5, connected to broach 115 at the front end, and linked to the pneumatic cavity of cylinder 111 at the rear end through piston 113. Disc spring 114: preload force is 500N, elastic stroke is 2mm, and tool change repeat positioning accuracy is ±1μm.

[0052] Cooling and gas circuit 14 system Cooling water circuit 16: Reciprocating spiral grooves (pitch 10mm, depth 3mm) are machined on the outer surface of the front / rear radial bearing 7 and the cylinder 111, the cooling water flow rate is 5L / min, the inlet water temperature is 25℃, and the outlet water temperature is ≤35℃. Gas circuit 14: Compressed air (0.6MPa) is input from the air inlet 15 of the rear end cover 2, and the gas is diverted to the radial bearing after passing through the tapered slit of the thrust bearing, and the gas utilization rate is increased by 35%.

[0053] Sensor system Displacement sensor 12: A magnetostrictive sensor with a resolution of 0.1 μm, integrated on the inner wall of the cylinder barrel 111, to detect the displacement of the push rod 112 in real time. Rotation speed sensor 13: A Hall effect sensor, to detect the signal of the encoder 25 at the end of the rotating shaft 5, with a sampling frequency of 10 kHz and an accuracy of ±5 rpm.

[0054] Working principle and operation steps Step 1: Start-up and suspension of the air bearing Compressed air is input from the air inlet 15 of the rear end cover 2 and flows through the tapered annular slits 84 of the front thrust bearing 8 and the rear thrust bearing 9. Since the inlet gap is larger than the outlet gap, the gas flow rate increases, forming a high-pressure gas film that pushes the thrust disc 24 of the rotating shaft 5 to be suspended bidirectionally, with an axial load-bearing capacity of 2000 N. The exhaust gas of the thrust bearing enters the gaps between the front and rear radial bearings (6, 7) and the rotating shaft 5 through the shunt channel 23 to form a radial gas film, realizing frictionless suspension.

[0055] Step 2: Start-up and machining of the drive motor 10 After the drive motor 10 is powered on, the stator 101 winding generates a rotating magnetic field, driving the rotor 102 and the rotating shaft 5 to rotate at a high speed of 60,000 rpm, directly driving the tool for ultra-precision cutting. The rotation speed sensor 13 monitors the rotation speed of the rotating shaft 5 in real time and feeds it back to the control system to dynamically adjust the input frequency of the motor to ensure that the rotation speed fluctuation rate < 0.01%.

[0056] Step 3: Cooling and thermal management Cooling water enters the spiral groove from the cooling water inlet 17 of the rear end cover 2, forming turbulent flows with alternating rotation directions, directly absorbing the frictional heat of the bearing gas film and the heat generated by the motor. The outlet water temperature ≤ 35 °C, and the temperature rise is controlled within 10 °C.

[0057] Step 4: Tool change operation Loosen the tool: Compressed gas is input from the pneumatic control interface of the tool puller 115 into the pneumatic cavity of the cylinder barrel 111, pushing the piston 113 and the push rod 112 forward by 2 mm, overcoming the pre-tightening force of the disc spring 114, and the tool puller 115 releases the tool holder 116. The displacement sensor 12 detects the displacement deviation in real time. Tighten the tool: After the gas is released, the disc spring 114 elastically returns, driving the push rod 112 to return, and the tool puller 115 locks the tool holder 116. The tool change operation takes 0.1 second.

[0058] Step 5: Condition monitoring and maintenance The sensor data is transmitted to the host computer through the sensor port 21 of the rear end cover 2 to display the operating status of the main shaft in real time. Clean air is continuously introduced into the gas film to prevent cutting fluid from invading the bearing gap, and the maintenance period is extended to 2000 hours.

[0059] Performance verification and effects Processing accuracy: At a rotational speed of 60,000 rpm, the radial runout of the spindle is ≤0.1 μm, and the axial runout is ≤0.05 μm, meeting the processing requirements of optical lenses. Energy consumption optimization: The gas reuse design reduces the consumption of compressed air by 35% and the comprehensive energy consumption by 25%. Heat dissipation efficiency: The 16-turbulence design of the cooling water path improves the heat exchange efficiency by 40%, and the temperature rise of the spindle is controlled within 10°C. Tool change reliability: The repeat positioning accuracy of tool change is ±1 μm, and the response time is 0.1 second, suitable for high-precision multi-process machining.

[0060] Summary In this embodiment, through the high-rigidity air bearing, hierarchical air supply, turbulent cooling, intelligent sensing and compact integrated design, the spindle realizes frictionless high-speed rotation, precise tool change, real-time monitoring and low-energy consumption operation, solves the technical bottlenecks of traditional air spindles in terms of rigidity, heat dissipation, accuracy and intelligent control, and is applicable to ultra-precision machining fields such as semiconductors and optical components.

[0061] The above are only the preferred embodiments of the present invention, and do not limit the scope of the present invention. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in 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, rotating shaft, front radial bearing, rear radial bearing, front thrust bearing, rear thrust bearing, drive motor, broaching mechanism; The front radial bearing, the front thrust bearing, the rear thrust bearing, the rear radial bearing, the drive motor and the 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 barrel to form a closed cavity; The rotating shaft passes through the front radial bearing, the front thrust bearing, the rear thrust bearing, the rear radial bearing, the drive motor, and the cylinder barrel arranged inside the housing, and the front end extends out of the front end cover for installing the tool, and the rear end is coaxially fixedly connected with the rotor of the drive motor; The rotating shaft is also fixedly provided with a thrust plate, and the front thrust bearing and the rear thrust bearing are respectively arranged on the front and rear end surfaces of the thrust plate of the rotating shaft; The broaching mechanism comprises a cylinder, a push rod, a piston, a disc spring, a broach and a handle; The push rod is arranged inside the rotating shaft, the front end of the push rod is connected to the broach, the rear end of the push rod is provided with a piston, the piston is arranged in the pneumatic cavity of the cylinder, the disc spring is arranged on the broach, and the handle is arranged in front of the broach; An air path is arranged in the shell, and the gas forms an air film between the thrust plate and the front thrust bearing, the rear thrust bearing, and between the rotating shaft and the front radial bearing, the rear radial bearing.

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 broach air control interface.

3. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The air paths of the front radial bearing and the rear radial bearing include a plurality of axial air holes evenly distributed in the circumferential direction, and the inlet end of the air path is communicated with the air inlet of the rear end cover.

4. The ultra-precision air-bearing electric spindle according to claim 1, characterized in that: The front thrust bearing and the rear thrust bearing are both composed of a first annular component and a second annular component connected by bolts, and 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 air film.

5. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The air inlet arranged on the rear end cover is used for inputting gas, and mutually connected air paths are arranged in the cylinder barrel and the shell. The gas enters the shell from the cylinder barrel, is input from the shell, and flows through the tapered annular slits of the front thrust bearing and the rear thrust bearing in sequence to form a high-pressure air film, and then is diverted to the axial air paths of the front radial bearing and the rear radial bearing, thereby completing the secondary utilization of the gas and improving the gas utilization rate.

6. The ultra-precision air-bearing electric spindle according to claim 1, characterized in that: A displacement sensor is provided on the inner wall of the pneumatic chamber of the cylinder of the broaching mechanism, which is used to detect the axial displacement of the push rod by detecting the movement of the piston; The rotating shaft is also provided with an encoder, which rotates together with the rotating shaft. A rotation speed sensor is also provided 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.

7. The ultra-precision air-bearing electric spindle according to claim 2, characterized in that: The pneumatic control interface of the broach is connected to the pneumatic chamber of the cylinder, and compressed gas is input into the pneumatic chamber of the cylinder to push the piston and the push rod forward, thereby overcoming the pre-tightening force of the disc spring to loosen the broach. After the gas is released, the disc spring elastically returns to complete the tightening of the broach.

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

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

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

Images