High-speed water-lubricated electric spindle with internal and external cooling

Abstract

The application provides a high-speed water-lubricated electric spindle with internal and external cooling, which comprises a shell, a hollow-structured spindle, a water-lubricated radial bearing, a water-lubricated thrust bearing, a high-speed motor, a tool assembly and a sealing assembly, and external and internal cooling channels arranged in the electric spindle. Cooling water and cooling gas in the external cooling channel cool the motor stator core, the motor stator winding, the radial bearing bush and the thrust bearing thrust pad; cooling liquid in the internal cooling channel cools the spindle core, the motor rotor, the radial bearing journal, the thrust bearing thrust disc, the tool assembly and the workpiece; the non-contact sealing of high-pressure supply of the cooling liquid is realized by utilizing the gill tooth, the front and rear aerodynamic seals; and the non-contact sealing of the water-lubricated bearing is realized by utilizing the centrifugal and aerodynamic seals. The application can effectively control the temperature rise of the whole electric spindle, further improve the limit working speed and dynamic characteristics of the spindle, and ensure the reliable sealing under the working conditions of high-speed operation and start-stop machine.

Description

Technical Field

[0001] This invention relates to the field of high-speed cutting equipment, and more specifically to a high-speed water-lubricated electric spindle with internal and external cooling. Background Technology

[0002] Currently, water-lubricated electric spindles are considered one of the future development directions for high-speed precision electric spindles. Compared with air-bearing electric spindles, water-lubricated electric spindles have the advantages of high load capacity, high rigidity, and good stability; compared with oil-lubricated electric spindles, they have the advantages of large flow rate, low temperature rise, and environmental friendliness. However, when water-lubricated electric spindles operate continuously for a long time under high-speed conditions, the fluid temperature rises due to the viscous shearing effect, and its viscosity decreases accordingly. This leads to a reduction in the load capacity and rigidity of the spindle bearing. At the same time, the increased fluid temperature also causes thermal deformation of the bearing, changing the bearing clearance and affecting the working characteristics of the water-lubricated bearing and the spindle. In addition, high-speed motors and cutting tools also generate a large amount of electromagnetic heat and frictional heat, causing temperature rise and thermal deformation of the spindle and tools, which in turn affects the service life and machining accuracy of the spindle.

[0003] Existing high-speed electric spindles supported by sliding bearings primarily rely on external spiral cooling water jackets installed on the motor stator to circulate coolant and cool the stator and spindle housing. This external cooling structure is simplistic and insufficient to remove internal heat. The main heat sources of the motor include stator core heating, winding copper loss heating, and rotor iron loss heating, accounting for approximately 60% of the total heat generated by the electric spindle. However, the stator windings and rotor, which currently account for more than two-thirds of the motor's heat generation, are not effectively cooled. Simultaneously, the heat source of the sliding bearings mainly originates from the viscous shear friction of the high-speed fluid in the bearing clearance, generating approximately 30% of the total spindle heat. Of this, some heat is transferred to the outside through the bearing bushes, some to the spindle core through the journals, and some is exchanged through fluid convection. Furthermore, during prolonged continuous machining, high-speed friction in the machining zone increases the cutting temperature, and heat from the cutting tool is also transferred to the spindle core. Currently, the cooling methods for high-speed electric spindles with sliding bearings are too simplistic and cannot effectively cool the entire electric spindle. Both the sliding bearings and the spindle core will experience severe temperature rise and thermal deformation, making it difficult to guarantee the machining accuracy of the spindle at high speeds.

[0004] The application of high-pressure cooling technology in machining offers significant technical advantages. Its precise high-pressure positioning creates a barrier between the coolant and the cutting edge, reducing the temperature in the cutting zone and extending tool life. However, supplying high-pressure coolant in high-speed cutting presents a major technical challenge: externally sprayed coolant struggles to reach the machining area; internally supplied coolant is problematic due to the long, narrow channels and extremely small nozzles on the tool, necessitating high-pressure cooling, which introduces new challenges to the reliable sealing of the high-speed spindle. Furthermore, leakage of lubricating water and coolant into the electric spindle motor can easily lead to corrosion and insulation damage, potentially causing serious accidents. Therefore, during high-speed operation and start-up / shutdown of the electric spindle, it is crucial to ensure reliable sealing during lubricating water discharge and high-pressure internal coolant supply. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide a high-speed water-lubricated electric spindle with internal and external cooling. The spindle is supported by a water-lubricated radial-thrust bearing. The high-speed motor, water-lubricated bearing, spindle core, and tool assembly are cooled through external and internal cooling channels. The invention also solves the problem of reliable sealing of the high-pressure coolant supply under high-speed operation and start-up / shutdown conditions, thereby effectively controlling the temperature rise of the entire electric spindle and further improving the bearing support rigidity and spindle rotation accuracy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-speed water-lubricated electric spindle with internal and external cooling includes a housing, a water-lubricated radial bearing disposed within the housing, a spindle disposed within the water-lubricated radial bearing, a tool assembly disposed at the front end of the spindle, a sealing assembly disposed at the end of the spindle, a water-lubricated thrust bearing disposed at the front end of the water-lubricated radial bearing, a high-speed motor disposed at the rear end of the water-lubricated radial bearing, a front cover, a rear cover, and a coolant supply sleeve, as well as external and internal cooling channels disposed within the electric spindle. The external cooling channel is used to cool the motor stator core, motor stator windings, water-lubricated radial bearing bushes, and water-lubricated thrust bearing thrust plates; the internal cooling channel is used to cool the spindle core, motor rotor, water-lubricated radial bearing journals, water-lubricated thrust bearing thrust plates, tool assembly, and milling operations; the sealing assembly is used to achieve a reliable seal between the spindle and the inner hole of the rear cover under high-speed operation and shutdown conditions.

[0008] Furthermore, the main shaft has a hollow structure with a through hole in the center for connecting coolant.

[0009] Furthermore, the rear end cover is provided with a bearing lubrication medium inlet, a cooling water inlet, a sealing-cooling gas inlet, and a water-gas outlet; the coolant supply sleeve is provided with a coolant inlet; and several coolant outlets are provided on the working surface of the cutting tool. Specifically, the bearing lubrication medium inlet is connected to an external high-pressure water supply device for introducing high-pressure lubricating water; the cooling water inlet is connected to an external normal-pressure water supply device for introducing normal-pressure cooling water; the sealing-cooling gas inlet is connected to an external air supply device for introducing compressed air; the coolant inlet is connected to an external pressurized liquid supply device for introducing coolant; the water-gas outlet is connected to an external recovery and circulation device for discharging the bearing lubrication medium, cooling water, and sealing-cooling gas; and the coolant outlets on the cutting tool working surface are used to spray coolant into the machining area.

[0010] Furthermore, the housing is provided with a bearing lubricating medium inlet channel, a cooling water inlet channel, a sealing-cooling gas inlet channel, and a water vapor outlet channel. Specifically, one end of the bearing lubricating medium inlet channel is connected to the bearing lubricating medium inlet, and the other end is completely blocked; one end of the cooling water inlet channel is connected to the cooling water inlet, and the other end is completely blocked; one end of the sealing-cooling gas inlet channel is connected to the sealing-cooling gas inlet, and the other end is completely blocked; one end of the water vapor outlet channel is connected to the water vapor outlet, and the other end is completely blocked.

[0011] Furthermore, the water-lubricated radial bearing adopts a large length-to-diameter ratio (ratio greater than 5) structure to improve the radial load-bearing capacity and radial support stiffness of the spindle. The water-lubricated radial bearing includes two parts: a radial bearing bush and a radial bearing journal. The radial bearing bush is housed in the housing, and the radial bearing journal is housed within the radial bearing bush, forming a section of the spindle. Two sets of radial throttling orifices are provided on the working surface of the radial bearing bush. The two sets of radial throttling orifices are separated by a pressure relief drainage ring groove and are symmetrically arranged on their front and rear sides. Each set of radial throttling orifices has several rows of radial throttling orifices arranged axially from front to back, and each row of radial throttling orifices has several radial throttling orifices, which are evenly arranged along the circumference. The radial throttling orifices are connected to the bearing lubricating medium inlet channel through corresponding inner water inlet holes, water inlet ring grooves, and outer water inlet holes.

[0012] Furthermore, the rear end of the water-lubricated radial bearing employs a combination of centrifugal and pneumatic seals to prevent lubricating water from entering the high-speed motor. Specifically, a liquid-throwing annular groove is provided on the outer circumference of the journal, forming a centrifugal seal; a gas-sealing annular groove is provided on the inner circumference of the bearing bush, forming a pneumatic seal. The lubricating medium thrown out by the liquid-throwing annular groove flows sequentially through an inner water-leaking annular groove, an inner water-leaking hole, an outer water-leaking annular groove, an outer water-leaking hole, and a water-gas discharge channel, finally exiting into an external recycling device. The gas-sealing annular groove connects sequentially to a sealing-cooling gas inlet channel through an inner air inlet hole, an outer air inlet annular groove, and an outer air inlet hole. When the lubricating medium at the front and middle ends of the water-lubricated radial bearing is discharged, it flows sequentially through a pressure-relief drainage annular groove, an inner drainage hole, an outer drainage annular groove, an outer drainage hole, and a water-gas discharge channel, finally exiting into the external recycling device.

[0013] Furthermore, the water-lubricated thrust bearing consists of two thrust pads (front and rear) and a thrust disc, which are located at the front end of the water-lubricated radial bearing and primarily provide axial load and axial stiffness to the main shaft. The front thrust pad is housed within the housing, while the rear thrust pad is integrally formed with the radial bearing bush. The front and rear thrust pads are symmetrically arranged on the front and rear sides of the adjusting ring, separated by an adjusting ring. The thrust disc is fixed to the main shaft and positioned between the front and rear thrust pads. Several axial throttling holes are provided on the working surfaces of both the front and rear thrust bearings, and are evenly distributed along the circumference. The axial throttling holes on the front thrust bearing are connected to the bearing lubricating medium water inlet channel through the inner water inlet hole, the water inlet ring groove, and the outer water inlet hole on the front end cover. The axial throttling holes on the rear thrust bearing are connected to the bearing lubricating medium water inlet channel through the inner water inlet hole, the water inlet ring groove, and the outer water inlet hole. The lubricating medium at the outer large diameter of the water-lubricated thrust bearing is discharged into the external recycling device through the inner drain hole, the drain ring groove, the outer drain hole, and the water and air discharge channel.

[0014] Furthermore, the inner front end of the water-lubricated thrust bearing employs a combination of centrifugal and pneumatic seals to prevent lubricating water from leaking from the electric spindle to the outside. Specifically, a liquid-throwing annular groove is provided on the outer circumference of the spindle, forming a centrifugal seal; a gas-sealing annular groove is provided on the inner circumference of the front end cover, forming a pneumatic seal. The lubricating medium thrown out by the liquid-throwing annular groove flows sequentially through a water-leaking annular groove, a water-leaking hole, and a water-air discharge channel, finally being discharged into an external recycling device. The gas-sealing annular groove is connected to a sealing-cooling gas inlet channel through an air inlet. The lubricating medium at the inner rear end of the water-lubricated thrust bearing first passes through a pressure-relief drainage annular groove at the front end of the water-lubricated radial bearing, then flows sequentially through an inner drainage hole, an outer drainage annular groove, another outer drainage hole, and a water-air discharge channel, finally being discharged into the external recycling device.

[0015] Furthermore, the tool assembly includes a tool and a tool holder; wherein, the tool has a plurality of internal cooling holes and a coolant outlet on its working surface; the tool holder is preferably a heat-shrink tool holder, which has internal cooling through holes and is installed on the front end of the spindle through external circumference positioning and threaded connection; the tool is clamped in the tool holder using heat-shrink fittings.

[0016] Furthermore, the high-speed motor is preferably a high-speed permanent magnet synchronous motor, whose rotor is lossless and does not generate heat; the motor stator is installed in the housing through a stator cooling sleeve, and the permanent magnet of the motor rotor is attached to the outer surface of the main shaft.

[0017] Furthermore, the external cooling channels include a first external cooling channel, a second external cooling channel, a third external cooling channel, and a fourth external cooling channel. Cooling water enters through a cooling water inlet, flows through the cooling water inlet channel and corresponding inlet holes on the housing, passes through the first, third, and fourth external cooling channels, and finally exits into the recycling device through corresponding drain holes and water vapor discharge channels on the housing. Cooling gas enters through a sealing-cooling gas inlet, flows through the sealing-cooling gas inlet channel and corresponding air inlet holes on the housing, passes through the second external cooling channel, and finally exits into the recycling device through corresponding exhaust holes and water vapor discharge channels on the housing. Specifically, the first external cooling channel is used to cool the motor stator core; the second external cooling channel is used to cool the motor stator windings; the third external cooling channel is used to cool the water-lubricated radial bearing bush; and the fourth external cooling channel is used to cool the water-lubricated thrust bearing thrust pad.

[0018] Furthermore, a double-helix cooling groove is provided on the outer circular surface of the motor stator cooling sleeve, and water inlet and drain holes are respectively provided on the upper and lower sides of the same axial position of the housing. The starting end of the double-helix cooling groove is connected to the cooling water inlet channel through the corresponding water inlet hole, and the end is connected to the water vapor discharge channel through the corresponding drain hole, which constitutes the first external cooling channel.

[0019] Furthermore, the front and rear ends of the motor stator cooling sleeve are respectively provided with an air inlet and an exhaust port. The air inlet is connected to the sealing-cooling gas inlet channel, and the exhaust port is connected to the water vapor outlet channel. The cooling gas flowing out from the front air inlet passes through the gap between the stator core and the stator winding, and then exits from the rear exhaust port, which constitutes the second external cooling channel.

[0020] Furthermore, on the outer circular surface of the two parts of the water-lubricated radial bearing bush separated by the pressure relief and exhaust ring groove, there is an external cooling ring groove between every two adjacent rows of radial throttling holes. The upper side of this external cooling ring groove is connected to the cooling water inlet channel through a corresponding water inlet hole, and the lower side is connected to the water vapor discharge channel through a corresponding drain hole, which constitutes the third external cooling channel.

[0021] Furthermore, an external cooling ring groove is provided on the outer circumference surface of the front and rear thrust bearings of the water-lubricated thrust bearing. The upper side of the external cooling ring groove is connected to the cooling water inlet channel through a corresponding water inlet hole, and the lower side is connected to the water vapor discharge channel through a corresponding drain hole, which constitutes the fourth external cooling channel.

[0022] Furthermore, the internal cooling channels include a first internal cooling channel, a second internal cooling channel, a third internal cooling channel, and a fourth internal cooling channel; coolant flows in through a coolant inlet, then passes through the first to fourth internal cooling channels, and finally reaches the machining area. Specifically, the first internal cooling channel is used to cool the motor rotor and spindle core; the second internal cooling channel is used to cool the journal of the water-lubricated radial bearing; the third internal cooling channel is used to cool the thrust plate of the water-lubricated thrust bearing and the spindle core; and the fourth internal cooling channel is used to cool the tool assembly and, in the milling process, also serves to cool the workpiece and remove chips.

[0023] Furthermore, the first internal cooling channel is disposed inside the motor rotor and part of the main shaft, and extends along the axial direction of the motor rotor and the main shaft. One end of the channel is connected to the end inlet of the central through hole of the main shaft, and the other end is connected to the second internal cooling channel.

[0024] Furthermore, the second internal cooling channel is disposed inside the journal of the water-lubricated radial bearing and extends along the axial direction of the journal, with one end connected to the first internal cooling channel and the other end connected to the third internal cooling channel.

[0025] Furthermore, the third internal cooling channel is disposed inside the water-lubricated thrust bearing thrust plate and part of the main shaft, and extends along the axial direction of the thrust plate and the main shaft. One end of the channel is connected to the second internal cooling channel, and the other end is connected to the fourth internal cooling channel.

[0026] Furthermore, the fourth internal cooling channel is disposed inside the tool assembly and extends along the axial direction of the cooling hole in the tool holder and the tool. One end of the channel is connected to the third internal cooling channel, and the other end is connected to the coolant outlet on the working surface of the tool.

[0027] Furthermore, the sealing assembly is composed of a toothed seal, a front pneumatic seal, a middle leakage annular groove, and a rear pneumatic seal, which is used to reliably seal the coolant in the coolant supply cup and maintain it at high pressure, preventing the coolant from leaking to the high-speed motor along the gap between the outer circular surface of the spindle end and the inner circular surface of the center hole of the rear end cover during start-up and shutdown. The inner wall of the central hole of the rear end cover is provided with several sealing teeth with a certain inclination angle, and a sealing cavity is provided between the sealing teeth, which constitutes the comb seal. The inner wall of the central hole of the rear end cover is also provided with a front gas sealing ring groove and a rear gas sealing ring groove along the axial direction. Both the front gas sealing ring groove and the rear gas sealing ring groove are connected to the sealing-cooling gas inlet channel through the air inlet hole, which constitutes the front pneumatic seal and the rear pneumatic seal. An intermediate leakage ring groove is provided in the middle of the front gas sealing ring groove and the rear gas sealing ring groove. It has a pressure relief function, making it difficult for the coolant to pass through the rear pneumatic seal. Even if a very small amount of coolant leaks out from the front pneumatic seal, it can be discharged into the water vapor discharge channel through the intermediate leakage ring groove and the leakage hole.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. This invention, on the one hand, cools the motor stator core, motor stator windings, water-lubricated radial bearing bushes, and water-lubricated thrust bearing thrust pads through the first to fourth external cooling channels; on the other hand, it cools the spindle core, water-lubricated radial bearing journals, water-lubricated thrust bearing thrust plates, and tool assemblies through the coolant in the first to fourth internal cooling channels. The internal and external cooling methods effectively control the temperature rise of the entire electric spindle, further improving the spindle's maximum operating speed and rotational accuracy, and extending the spindle's service life. Simultaneously, the coolant sprayed from the tool's working surface also cools the workpiece and removes chips during the milling process.

[0030] 2. A combined sealing structure consisting of a toothed seal, a front pneumatic seal, and a rear pneumatic seal is used to achieve non-contact sealing for high-pressure internal coolant supply; at the same time, a combined sealing structure consisting of a centrifugal seal and a pneumatic seal is used to achieve non-contact sealing for safe discharge and recovery of lubricating medium from high-speed water-lubricated bearings; and the two combined sealing structures can not only ensure reliable sealing of the electric spindle under high-speed operation, but also ensure effective sealing under start-up and shutdown conditions. Attached Figure Description

[0031] Figure 1 This is a schematic cross-sectional view of a high-speed water-lubricated electric spindle with internal and external cooling according to the present invention.

[0032] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure at point AA.

[0033] Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure at point BB.

[0034] Figure 4 for Figure 1 Schematic diagram of the cross-sectional structure at point CC.

[0035] Figure 5 for Figure 4 Enlarged view of a portion of the structure (schematic diagram of the sealing assembly of the present invention).

[0036] Figure 6 This is a schematic diagram of the tool assembly structure of the present invention.

[0037] Explanation of reference numerals in the attached drawings: 1-Housing, 101-Bearing lubricating medium inlet channel, 102-Cooling water inlet channel, 103-Sealing-cooling gas inlet channel, 104-Water and gas exhaust channel, 105-First external cooling channel water inlet, 106-Second external cooling channel air inlet, 107-108-Third external cooling channel first and second water inlets, 109-110-Fourth external cooling channel first and second water inlets, 111-114-Radial bearing first to fourth external water inlets, 115-Rear thrust bearing external water inlet, 116-Radial bearing gas seal external air inlet, 117-First external cooling channel drain hole, 118-Second external cooling channel exhaust hole, 119-120-Third external cooling channel exhaust hole. 1-Second drain holes of channel 1, 121-122-First and second drain holes of fourth external cooling channel, 123-Outer drain hole at the middle of radial bearing, 124-Outer drain hole at the front end of radial bearing, 125-Outer drain hole of thrust bearing, 126-Outer water leakage hole of radial bearing seal, 2-Spindle, 201-Spindle center through hole, 202-Radial bearing seal liquid-throwing ring groove, 203-Thrust bearing seal liquid-throwing ring groove, 3-Water-lubricated radial bearing, 301-Radial bearing bush, 302-Radial bearing journal, 303-306-First to fourth inner water inlet holes of radial bearing, 307-310-First to fourth water inlet ring grooves of radial bearing, 311-312-First and second cooling ring grooves of third external cooling channel, 313-Radial shaft 314 - Radial bearing front end pressure relief drainage ring groove; 315 - Radial bearing middle end inner drain hole; 316 - Radial bearing front end inner drain hole; 317 - Radial bearing middle end outer drain ring groove; 318 - Radial bearing front end outer drain ring groove; 319 - Radial bearing seal inner leakage ring groove; 320 - Radial bearing seal inner leakage hole; 321 - Radial bearing seal outer leakage ring groove; 322 - Radial bearing gas seal ring groove; 323 - Radial bearing gas seal inner air inlet hole; 324 - Radial bearing gas seal outer air inlet ring groove; 325 - Radial throttling orifice; 326 - Radial bearing seal ring; 4 - Water lubricated thrust bearing; 401 - Front thrust bearing; 402 - Rear thrust bearing; 403 - Thrust plate; 404 - Adjusting ring, 405 to 406 - First and second cooling ring grooves of the fourth cooling channel, 407 - Water inlet ring groove of the front thrust bearing, 408 - Water inlet ring groove of the rear thrust bearing, 409 - Water inlet hole inside the front thrust bearing, 410 - Water inlet hole inside the rear thrust bearing, 411 - Drain hole inside the thrust bearing, 412 - Axial throttling orifice, 413 - Drain ring groove of the thrust bearing, 414 - Thrust bearing seal ring, 5 - High-speed permanent magnet synchronous motor, 501 - Motor stator core, 502 - Motor stator winding, 503 - Motor rotor, 504 - Motor stator cooling sleeve, 50401 - Double spiral cooling groove, 50402 - Air inlet hole inside the second external cooling channel, 50403 - Exhaust hole inside the second external cooling channel, 6 - Tool assembly, 601 - End mill.602-Tool holder, 603-End mill internal cooling hole, 604-Tool holder internal cooling through hole, 605-Tool surface coolant outlet, 7-Sealing assembly, 701-Grate teeth, 702-Front gas seal ring groove, 703-Rear gas seal ring groove, 704-Intermediate leakage ring groove, 705-Front gas seal inlet, 706-Rear gas seal inlet, 707-Intermediate leakage hole, 8-External cooling channel, 9-Internal cooling channel, 10-Front end cap, 1001-Front end cap Thrust bearing outer water inlet, 1002-Thrust bearing seal leakage ring groove, 1003-Thrust bearing seal leakage hole, 1004-Thrust bearing gas seal ring groove, 1005-Thrust bearing gas seal air inlet, 11-Rear end cap, 1101-Bearing lubrication medium inlet, 1102-Cooling water inlet, 1103-Seal-cooling gas inlet, 1104-Water and gas outlet, 1105-Rear end cap center hole, 12-Coolant supply sleeve cup, 1201-Coolant inlet. Detailed Implementation

[0038] The following will be combined with the appendix Figures 1 to 6 The present invention will be described in further detail, but this does not limit the invention to the scope of the embodiments.

[0039] See Figures 1 to 4This invention discloses a high-speed water-lubricated electric spindle with internal and external cooling, comprising a housing 1, a spindle 2, a water-lubricated radial bearing 3, a water-lubricated thrust bearing 4, a high-speed permanent magnet synchronous motor 5, a tool assembly 6, a sealing assembly 7 at the end of the spindle, a front cover 10, a rear cover 11, and an internal coolant supply sleeve 12, as well as external cooling channels 8 and internal cooling channels 9 disposed in the electric spindle. The spindle 2 is supported by the water-lubricated radial bearing 3 and the water-lubricated thrust bearing 4, and has a hollow structure with a through hole 201 in the center for connecting coolant. The rear cover 11 is provided with a bearing lubrication medium inlet 1101, a cooling water inlet 1102, a sealing-cooling gas inlet 1103, and a water-gas outlet 1104; the coolant supply sleeve 12 is provided with a coolant inlet 1201; and the working surface of the milling cutter 601 is provided with a plurality of coolant outlets 605. Specifically, the bearing lubrication medium inlet 1101 is connected to an external high-pressure water supply device for introducing high-pressure lubrication water; the cooling water inlet 1102 is connected to an external normal-pressure water supply device for introducing normal-pressure cooling water; the sealing-cooling gas inlet 1103 is connected to an external air supply device for introducing compressed air; the coolant inlet 1201 is connected to an external pressurized liquid supply device for introducing coolant; the water-air outlet 1104 is connected to an external recycling device for discharging the bearing lubrication water, cooling water, and sealing-cooling gas; and the tool working surface coolant outlet 605 is used to spray coolant into the machining area. The housing 1 is provided with a bearing lubricating medium inlet channel 101, a cooling water inlet channel 102, a sealing-cooling gas inlet channel 103, and a water-gas outlet channel 104. One end of the bearing lubricating medium inlet channel 101 is connected to the bearing lubricating medium inlet 1101, one end of the cooling water inlet channel 102 is connected to the cooling water inlet 1102, one end of the sealing-cooling gas inlet channel 103 is connected to the sealing-cooling gas inlet 1103, and one end of the water-gas outlet channel 104 is connected to the water-gas outlet 1104. The other ends of all four channels are completely blocked.

[0040] See Figure 1 , Figure 3 and Figure 4The water-lubricated radial bearing 3 consists of two parts: a radial bearing bush 301 and a radial bearing journal 302. The radial bearing bush 301 is housed in the housing 1, and the radial bearing journal 302 is a section of the main shaft 2. The radial bearing bush 301 has two sets of radial throttling orifices, separated by a pressure relief drainage ring groove 313 at the center of the radial bearing, and symmetrically arranged on its front and rear sides. Each set of radial throttling orifices has several rows arranged axially from front to back, and each row has several radial throttling orifices 325, evenly arranged circumferentially. The radial throttling orifices 325 are connected to the bearing lubrication medium inlet channel 101 through the corresponding first to fourth inner water inlet holes (303 to 306), the first to fourth water inlet ring grooves (307 to 310), and the first to fourth outer water inlet holes (111 to 114), respectively. The inner circular surface of the radial bearing bush 301 is provided with a radial bearing middle pressure relief drainage ring groove 313 and a radial bearing front pressure relief drainage ring groove 314. When the lubricating medium in the middle and front parts of the water-lubricated radial bearing is discharged, it flows sequentially through the radial bearing middle and front pressure relief drainage ring grooves (313 and 314), the radial bearing middle and front inner drainage holes (315 and 316), the radial bearing middle and front outer drainage ring grooves (317 and 318), the radial bearing middle and front outer drainage holes (123 and 124), and the water and air discharge channel 104, and is finally discharged into the external recycling device. The outer circumference of the radial bearing bush 301 is provided with the first to second cooling ring grooves (311 to 312) of the third external cooling channel, and radial bearing seals 326 are installed on both sides of each cooling ring groove. The upper side of the first to second cooling ring grooves (311 to 312) of the third external cooling channel is connected to the cooling water inlet channel 102 through the first to second water inlet holes (107 to 108) of the third external cooling channel, and the lower side is connected to the water vapor discharge channel 104 through the first to second drain holes (119 to 120) of the third external cooling channel. A radial bearing seal fluid-throwing ring groove 202 is provided on the outer circle of the main shaft 2, and a radial bearing gas seal ring groove 322 is provided on the inner circle of the radial bearing bush 301. This constitutes a combined sealing structure composed of centrifugal seal and pneumatic seal, which is used to prevent the lubricating water discharged from the rear end of the radial bearing from entering the interior of the high-speed motor. The lubricating medium thrown out by the radial bearing seal fluid-throwing ring groove 202 flows sequentially through the radial bearing seal inner leakage ring groove 319, the radial bearing seal inner leakage hole 320, the radial bearing seal outer leakage ring groove 321, the radial bearing seal outer leakage hole 126, and the water and gas discharge channel 104, and is finally discharged into the external recycling device. The radial bearing gas seal ring groove 322 is connected to the sealing-cooling gas inlet channel 103 sequentially through the radial bearing gas seal inner air inlet hole 323, the radial bearing gas seal outer air inlet ring groove 324, and the radial bearing gas seal outer air inlet hole 116.

[0041] See Figure 1 , Figure 3 and Figure 4The water-lubricated thrust bearing 4 is located at the front end of the water-lubricated radial bearing 3 and consists of a front thrust bearing 401, a rear thrust bearing 402, and a thrust plate 403. The front thrust bearing 401 is located in the housing 1, and the rear thrust bearing 402 is integrally formed with the radial bearing bush 301. The front thrust bearing 401 and the rear thrust bearing 402 are separated by an adjusting ring 404 and are symmetrically arranged on their front and rear sides. The thrust plate 403 is integrally formed with the main shaft 2 and is located between the front and rear thrust bearings. Both the front and rear thrust bearings (401 and 402) have several axial throttling holes 412 evenly distributed along the circumference on their working surfaces. The axial throttling holes 412 on the front thrust bearing 401 connect sequentially to the bearing lubrication medium inlet channel 101 via the inner water inlet hole 409, the water inlet ring groove 407, and the outer water inlet hole 1001. The axial throttling holes 412 on the rear thrust bearing 402 connect sequentially to the bearing lubrication medium inlet channel 101 via the inner water inlet hole 410, the water inlet ring groove 408, and the outer water inlet hole 115. The water-lubricated thrust bearing 4... The lubricating medium at the outer large diameter passes sequentially through the inner drain hole 411 of the thrust bearing, the drain ring groove 413 of the thrust bearing, the outer drain hole 125 of the thrust bearing, and the water and air discharge channel 104, and is finally discharged into the external recycling device. Similar to the discharge of the lubricating medium at the front end of the water-lubricated radial bearing, the lubricating medium at the inner rear end of the water-lubricated thrust bearing 4 also first passes through the pressure relief drain ring groove 314 at the front end of the radial bearing, and then flows sequentially through the inner drain hole 316 at the front end of the radial bearing, the outer drain ring groove 318 at the front end of the radial bearing, the outer drain hole 124 at the front end of the radial bearing, and the water and air discharge channel 104, and is finally discharged into the external recycling device. The front thrust bearing 401 and the rear thrust bearing 402 are respectively provided with the first (405) and the second (406) cooling ring grooves of the fourth external cooling channel on their outer circles, and the thrust bearing seal ring 414 is installed on both sides of each cooling ring groove. The upper side of the first (405) and the second (406) cooling ring grooves of the fourth external cooling channel are connected to the cooling water inlet channel 102 through the first (109) and the second (110) water inlet holes of the fourth external cooling channel, respectively, and the lower side is connected to the water vapor discharge channel 104 through the first (121) and the second (122) drain holes of the fourth external cooling channel, respectively. The outer circumference of the main spindle 2 is provided with a thrust bearing sealing fluid-throwing ring groove 203, and the inner circumference of the front end cover 10 is provided with a thrust bearing gas sealing ring groove 1004. This constitutes a combined sealing structure consisting of a centrifugal seal and a pneumatic seal, which is used to prevent lubricating water from leaking from the inside of the electric spindle to the outside. The lubricating medium thrown out by the thrust bearing sealing fluid-throwing ring groove 203 flows sequentially through the thrust bearing sealing water leakage ring groove 1002, the thrust bearing sealing water leakage hole 1003, and the water and gas discharge channel 104, and is finally discharged into the external recycling device. The thrust bearing gas sealing ring groove 1004 is connected to the sealing-cooling gas inlet channel 103 through the thrust bearing gas sealing air inlet hole 1005.

[0042] See Figures 1 to 4 The high-speed permanent magnet synchronous motor 5 is located at the rear end of the water-lubricated radial bearing 3 and consists of a motor stator and a motor rotor. The motor stator core 501 is interference-fitted into the inner hole of the motor stator cooling sleeve 504, the motor stator winding 502 is wound around the motor stator core 501, and the motor rotor permanent magnet 503 is surface-mounted on the outer cylindrical surface of the main shaft 2. The motor stator cooling sleeve 504 is interference-fitted into the inner hole of the housing 1, and its outer cylindrical surface is provided with a double-helix cooling groove 50401. The beginning of this double-helix cooling groove 50401 is connected to the cooling water inlet channel 102 through the first external cooling channel water inlet hole 105, and the end is connected to the water vapor outlet channel 104 through the first external cooling channel drain hole 117. The front and rear ends of the motor stator cooling sleeve 504 are respectively provided with a second external cooling channel air inlet hole 50402 and a second external cooling channel exhaust hole 50403.

[0043] See Figure 1 and Figure 6 The tool assembly 6 consists of a milling cutter 601 and a tool holder 602. The milling cutter 601 has several internal cooling holes 603 and a coolant outlet 605 on its working surface. The tool holder 602 is a heat-shrink tool holder with internal cooling through holes 604 and is installed at the front end of the spindle 2 through external positioning and threaded connection. The milling cutter 601 is clamped in the tool holder 602 using heat-shrink fittings.

[0044] See Figure 1 , Figure 4 and Figure 5 The sealing assembly 7 is located at the end of the main shaft 2 and is composed of a grate seal, a front pneumatic seal, a middle leakage annular groove, and a rear pneumatic seal, achieving a high-pressure and reliable seal for the coolant supplied to the sleeve cup. Several grate teeth 701 with a certain inclination angle are provided on the inner wall of the center hole 1105 of the rear end cover, with sealing cavities between the grate teeth, thus forming the grate seal. A front gas sealing annular groove 702 and a rear gas sealing annular groove 703 are also provided axially on the inner wall of the center hole 1105 of the rear end cover, and the front and rear gas sealing annular grooves... The grooves are connected to the sealing-cooling gas inlet channel 103 through the front and rear gas seal inlet holes (705 and 706), which constitute the front pneumatic seal and the rear pneumatic seal. An intermediate leakage annular groove 704 is provided between the front gas seal annular groove 702 and the rear gas seal annular groove 703. It has a pressure relief function, making it difficult for the coolant to pass through the rear pneumatic seal. Even if a very small amount of coolant leaks out from the front pneumatic seal, it can be discharged into the water and gas discharge channel 104 through the intermediate leakage annular groove 704 and the intermediate leakage hole 707.

[0045] See Figure 1 , Figure 3 and Figure 4 The external cooling channel 8 includes a first external cooling channel, a second external cooling channel, a third external cooling channel, and a fourth external cooling channel. Cooling water enters the cooling water inlet channel 102 through the cooling water inlet 1102, and cooling gas enters the sealing-cooling gas inlet channel 103 through the sealing-cooling gas inlet 1103. Simultaneously, the cooling water and cooling gas flowing into the water-gas outlet channel 104 are finally discharged into the recycling device through the water-gas outlet 1104. Firstly, the cooling water in the cooling water inlet channel 102 flows into the double spiral cooling groove 50401 on the motor stator cooling jacket 504 through the water inlet hole 105 of the first external cooling channel, and then flows into the water-gas outlet channel 104 through the drain hole 117 of the first external cooling channel, thereby cooling the motor stator core 501, which constitutes the first external cooling channel. Secondly, the cooling air in the sealed-cooling gas inlet channel 103 flows sequentially through the outer air inlet 106 and the inner air inlet 50402 of the second external cooling channel into the gap between the motor stator core 501 and the motor stator winding 502. Then, it flows sequentially through the inner exhaust port 50403 and the outer exhaust port 118 of the second external cooling channel into the water vapor discharge channel 104, thus cooling the motor stator winding 502. This constitutes the second external cooling channel. Thirdly, the cooling water in the cooling water inlet channel 102 flows sequentially through the first and second inlet ports (107 and 108) of the third external cooling channel into the first and second cooling ring grooves (311 and 312). Then, it flows sequentially through the first and second drain ports (119 and 120) of the third external cooling channel into the water vapor discharge channel 104, thus cooling the radial bearing bush 301. This constitutes the third external cooling channel. Fourth, the cooling water in the cooling water inlet channel 102 flows into the first and second cooling ring grooves (405 and 406) of the fourth external cooling channel through the first and second inlet holes (109 and 110) of the fourth external cooling channel, and then flows into the water vapor discharge channel 104 through the first and second drain holes (121 and 122) of the fourth external cooling channel, thereby cooling the front thrust bearing 401 and the rear thrust bearing 402 of the thrust bearing. This constitutes the fourth external cooling channel.

[0046] See Figure 1 and Figure 6The internal cooling channel 9 includes a first internal cooling channel, a second internal cooling channel, a third internal cooling channel, and a fourth internal cooling channel. Coolant enters the cooling air supply sleeve 12 through the coolant inlet 1201, then passes through the first to fourth internal cooling channels, and finally reaches the processing area. Firstly, the first internal cooling channel is located inside a portion of the motor rotor 503 and the spindle 2, extending along the axis of the spindle's central through-hole 201. One end of the channel connects to the end inlet of the spindle's central through-hole 201, and the other end connects to the second internal cooling channel, used to cool the motor rotor 503 and the spindle core 2. Secondly, the second internal cooling channel is located inside the water-lubricated radial bearing journal 302, extending along the axis of the spindle's central through-hole 201. One end of the channel connects to the first internal cooling channel, and the other end connects to the third internal cooling channel, used to cool the water-lubricated radial bearing journal 302. Thirdly, the third internal cooling channel is located inside the water-lubricated... The thrust bearing thrust plate 403 and part of the spindle 2 are located inside the spindle and extend along the axis of the spindle center through hole 201. One end of the latter is connected to the second internal cooling channel and the other end is connected to the fourth internal cooling channel. This channel is used to supply water for lubrication and cooling of the thrust bearing thrust plate 403 and the spindle core 2. Fourthly, the fourth internal cooling channel is located inside the tool assembly 6 and extends along the axis of the tool holder internal cooling through hole 604 and the tool internal cooling hole 603. One end of the former is connected to the third internal cooling channel and the other end is connected to the coolant outlet 605 on the milling cutter working surface. This channel is used not only for cooling the tool assembly but also for cooling the workpiece and removing chips during milling.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations will be apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the basic spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-speed water-lubricated electric spindle with internal and external cooling, characterized in that: The electric spindle includes a housing (1), a water-lubricated radial bearing (3) disposed in the housing, a spindle (2) disposed in the water-lubricated radial bearing, a tool assembly (6) disposed at the front end of the spindle, a sealing assembly (7) disposed at the end of the spindle, a water-lubricated thrust bearing (4) disposed at the front end of the water-lubricated radial bearing, a high-speed motor (5) disposed at the rear end of the water-lubricated radial bearing, a rear end cover (11) and a coolant supply sleeve (12), and an external cooling channel (8) and an internal cooling channel (9) disposed in the electric spindle; The main shaft (2) has a hollow structure with a through hole (201) in the center for connecting the coolant; the housing (1) is provided with a cooling water inlet channel (102), a sealing-cooling gas inlet channel (103) and a water vapor outlet channel (104); the rear end cover (11) is provided with a cooling water inlet (1102), a sealing-cooling gas inlet (1103) and a water vapor outlet (1104); the coolant supply sleeve (12) is provided with a coolant inlet (1201); The external cooling channel (8) includes a first external cooling channel, a second external cooling channel, a third external cooling channel, and a fourth external cooling channel; cooling water enters through the cooling water inlet (1102), passes through the cooling water inlet channel (102) and corresponding inlet holes (105, 107 to 108, 109 to 110) on the shell, flows through the first, third, and fourth external cooling channels, and finally exits into the recycling device through the corresponding drain holes (117, 119 to 120, 121 to 122) and the water vapor discharge channel (104) on the shell; cooling gas enters through the sealed-cooling gas inlet (1103), After passing through the sealed-cooling gas inlet channel (103) and the corresponding inlet hole (106) on the housing, the gas flows through the second external cooling channel and finally exits into the recycling device through the corresponding exhaust hole (118) and the water vapor discharge channel (104) on the housing. The first external cooling channel is used to cool the motor stator core (501), the second external cooling channel is used to cool the motor stator winding (502), the third external cooling channel is used to cool the water-lubricated radial bearing bush (301), and the fourth external cooling channel is used to cool the front and rear thrust bushes (401, 402) of the water-lubricated thrust bearing. The internal cooling channel (9) includes a first internal cooling channel, a second internal cooling channel, a third internal cooling channel and a fourth internal cooling channel; the coolant flows in from the coolant inlet (1201), then passes through the first to fourth internal cooling channels, and finally reaches the processing area; wherein, the first internal cooling channel is used to cool the motor rotor (503) and the spindle (2), the second internal cooling channel is used to cool the water-lubricated radial bearing journal (302), the third internal cooling channel is used to cool the water-lubricated thrust bearing thrust plate (403) and the spindle (2), and the fourth internal cooling channel is used to cool the tool assembly (6), and plays the role of cooling the workpiece and removing chips in the processing process; The sealing assembly (7) is composed of a toothed seal, a front pneumatic seal, a middle leakage annular groove and a rear pneumatic seal, used to reliably seal the coolant in the coolant supply cup (12) and keep it at high pressure.

2. The high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: The housing (1) is also provided with a bearing lubrication medium inlet channel (101); the rear end cover (11) is also provided with a bearing lubrication medium inlet (1101); a number of coolant outlets (605) are provided on the working surface of the tool; the bearing lubrication medium inlet (1101) is connected to an external high-pressure water supply device for introducing high-pressure lubrication water medium, the coolant inlet (1102) is connected to an external normal pressure water supply device for introducing normal pressure coolant water, and the sealing-cooling gas inlet (1103) is connected to an external air supply device for introducing compressed air; The coolant inlet (1201) is connected to the external pressurized liquid supply device for introducing coolant; the water and gas outlet (1104) is connected to the external recovery and circulation device for discharging bearing lubricating water, cooling water and sealing and cooling gas. One end of the bearing lubricating medium inlet channel (101) is connected to the bearing lubricating medium inlet (1101), one end of the cooling water inlet channel (102) is connected to the cooling water inlet (1102), one end of the sealing-cooling gas inlet channel (103) is connected to the sealing-cooling gas inlet (1103), and one end of the water and gas outlet channel (104) is connected to the water and gas outlet (1104).

3. A high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: The water-lubricated radial bearing (3) has a length-to-diameter ratio greater than 5.

4. A high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: The rear end of the water-lubricated radial bearing (3) adopts a combination of centrifugal seal and pneumatic seal to prevent lubricating water from entering the interior of the high-speed motor. The journal (302) is provided with a liquid-throwing ring groove (202) on the outer circle, which constitutes the centrifugal seal. The bearing bush (301) is provided with a gas sealing ring groove (322) on the inner circle, which constitutes the pneumatic seal. The lubricating medium thrown out by the liquid-throwing ring groove (202) flows sequentially through the inner water leakage ring groove (319), the inner water leakage hole (320), the outer water leakage ring groove (321), the outer water leakage hole (126), and the water and gas discharge channel (104), and is finally discharged into the external recycling device. The gas sealing ring groove (322) is connected to the sealing-cooling gas inlet channel (103) sequentially through the inner air inlet hole (323), the outer air inlet ring groove (324), and the outer air inlet hole (116).

5. A high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: The inner front end of the water-lubricated thrust bearing (4) adopts a combination of centrifugal seal and pneumatic seal to prevent lubricating water from leaking from the inside of the electric spindle to the outside. The spindle (2) has a liquid-throwing ring groove (203) on its outer circle, which constitutes the centrifugal seal. The front end cover (10) has a gas sealing ring groove (1004) on its inner circle, which constitutes the pneumatic seal. The lubricating medium thrown out by the liquid-throwing ring groove (203) flows through the water leakage ring groove (1002), the water leakage hole (1003) and the water and gas discharge channel (104) in sequence, and is finally discharged into the external recycling device. The gas sealing ring groove (1004) is connected to the sealing-cooling gas inlet channel (103) through the air inlet hole (1005).

6. A high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: A double-spiral cooling groove (50401) is provided on the outer circular surface of the motor stator cooling sleeve (504). The beginning of the double-spiral cooling groove (50401) is connected to the cooling water inlet channel (102) through the water inlet hole (105), and the end is connected to the water vapor discharge channel (104) through the drain hole (117). This constitutes the first external cooling channel. The front end and rear end of the motor stator cooling sleeve (504) are respectively provided with an air inlet hole (50402) and an exhaust hole (50403). The air inlet hole (50402) is connected to the sealing-cooling gas inlet channel (103), and the exhaust hole (50403) is connected to the water vapor discharge channel (104). The cooling gas flowing out from the front air inlet hole (50402) passes through the gap between the stator core (501) and the stator winding (502) and is discharged from the rear exhaust hole (50403). This constitutes the first external cooling channel. The second external cooling channel; an external cooling ring groove (311 to 312) is provided between every two adjacent rows of radial throttling holes (325) on the outer surface of the water-lubricated radial bearing bush (301). The upper side of this external cooling ring groove is connected to the cooling water inlet channel (102) through the water inlet hole (107 to 108), and the lower side is connected to the water vapor discharge channel (104) through the drain hole (119 to 120). This constitutes the third external cooling channel; an external cooling ring groove (405 to 406) is provided on the outer surface of the front and rear thrust bushes (401 and 402) of the water-lubricated thrust bearing. The upper side of this external cooling ring groove is connected to the cooling water inlet channel (102) through the water inlet hole (109 to 110), and the lower side is connected to the water vapor discharge channel (104) through the drain hole (121 to 122). This constitutes the fourth external cooling channel.

7. A high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: The first internal cooling channel is located inside the motor rotor (503) and part of the spindle (2), and extends along the axial direction of the motor rotor and the spindle, with one end connected to the end inlet of the spindle center through hole; the second internal cooling channel is located inside the water-lubricated radial bearing journal (302), and extends along the axial direction of the journal, with one end connected to the first internal cooling channel; the third internal cooling channel is located inside the water-lubricated thrust bearing thrust plate (403) and part of the spindle (2), and extends along the axial direction of the thrust plate and the spindle, with one end connected to the second internal cooling channel; the fourth internal cooling channel is located inside the tool assembly (6), and extends along the axial direction of the tool holder and the tool internal cooling through holes (603 and 604), with one end connected to the coolant outlet (605) of the tool working surface; the first to fourth internal cooling channels are connected to each other end to end.

8. A high-speed water-lubricated electric spindle with internal and external cooling as described in claim 1, characterized in that: The inner wall of the central hole (1105) of the rear end cover is provided with several sealing teeth (701) with a certain inclination angle, and a sealing cavity is provided between the sealing teeth, which constitutes the tooth seal; the inner wall of the central hole (1105) of the rear end cover is also provided with a front gas sealing ring groove (702) and a rear gas sealing ring groove (703) along the axial direction, and the front gas sealing ring groove and the rear gas sealing ring groove are respectively connected to the sealing-cooling gas through the air inlet (705 and 706). The air intake channel (103) is connected, which constitutes the front pneumatic seal and the rear pneumatic seal; an intermediate leakage annular groove (704) is provided in the middle of the front gas seal annular groove and the rear gas seal annular groove, which has a pressure relief function, making it difficult for the coolant to pass through the rear pneumatic seal. Even if a very small amount of coolant leaks out from the front pneumatic seal, it can be discharged to the water vapor discharge channel (104) through the intermediate leakage annular groove (704) and the leakage hole (707).

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