High-efficiency cooling super-high-speed drilling air-floating electric spindle

Abstract

The application provides a high-efficiency cooling super-high-speed drilling air-floating electric spindle, which comprises a shell, a hollow-structured spindle, a radial air-floating bearing, a thrust air-floating bearing, a high-speed motor, a cutter assembly and a dynamic sealing assembly, and external cooling channels and internal cooling channels arranged in the electric spindle. The external cooling channels are used for cooling the motor stator core, the motor stator winding, the radial bearing bush and the thrust bearing thrust pad; the internal cooling channels are used for cooling the spindle core, the motor rotor, the radial bearing journal, the thrust bearing thrust disc and the cutter assembly, and can also play a role in cooling workpieces and chip breaking and chip removal in the drilling process; and the dynamic sealing of the high-pressure supply of the internal cooling air is realized by using the pumping effect of the spiral micro-groove when the spindle rotates at a high speed. The application can effectively control the temperature rise of the whole electric spindle, further improve the limit working speed of the spindle and the machining precision, and all air cooling is adopted, so that the peripheral auxiliary devices are simplified.

Description

Technical Field

[0001] This invention relates to the field of high-speed cutting equipment, and specifically to an ultra-high-speed drilling air-floating electric spindle with high-efficiency cooling. Background Technology

[0002] Currently, the development of multilayer high-density printed circuit boards (PCBs) has led to a dramatic increase in the number of micro-holes requiring machining on these boards, and the quality requirements for micro-hole machining have also risen to a new level. To meet the high-precision and high-efficiency machining requirements of ultra-micro-holes in PCBs, ultra-high-speed drilling air-operated spindles have emerged. These spindles use air as a lubricant and feature low frictional resistance, high operating speed, high rotational accuracy, low vibration, and no pollution, effectively meeting the machining requirements for drilling efficiency of high-density holes and drilling quality of micro-holes in PCBs. However, when the spindle operates continuously at ultra-high speeds for extended periods, the motor, bearings, and drill bit generate significant amounts of electromagnetic and frictional heat, leading to temperature rise and thermal deformation of the spindle and cutting tools, thus affecting the spindle's performance and service life.

[0003] Currently, high-speed electric spindles supported by rolling bearings typically employ external circulating cooling structures to cool the motor stator core and the outer rings of the rolling bearings. While oil-air lubrication at the bearings can also remove some heat, a significant portion remains transferred to the spindle and is difficult to cool, causing a temperature rise. For high-speed electric spindles supported by air bearings, this temperature rise will cause thermal deformation of the air bearing journals and thrust plates mounted on the spindle, leading to changes in the air bearing clearance. It is worth noting that the change in bearing clearance caused by this thermal deformation can be on the same order of magnitude as, or even an order of magnitude higher than, the design clearance of the air bearing, severely impacting bearing performance.

[0004] Furthermore, during continuous drilling, the high-speed friction between the drill bit and the hole wall raises the cutting temperature, leading to serious problems such as resin melting and contamination on the printed circuit board. Simultaneously, some heat from the drill bit is transferred to the spindle, causing thermal deformation. Therefore, tool cooling is necessary. For drilling micro-holes in printed circuit boards, drilling coolant not only contaminates the workpiece but also requires additional auxiliary equipment for the air-bearing electric spindle. Moreover, liquid seals are prone to leakage. Therefore, an effective approach is to use cooling air to cool the drilling process. However, supplying drilling cooling air presents a significant challenge: externally sprayed cooling air struggles to reach the drilling zone; internally supplied cooling air requires pressurized air due to the very small vent holes on the drill bit, posing a new challenge to the high-speed dynamic seal of the spindle. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide an ultra-high-speed drilling air-bearing electric spindle with high-efficiency cooling. The spindle is supported by a radial-thrust air bearing and the motor, bearings, spindle and cutting tools are cooled through external and internal cooling channels. It also solves the dynamic sealing problem of high-pressure internal cooling air supply under high-speed conditions, thereby effectively controlling the temperature rise of the entire electric spindle and further improving the spindle's maximum operating speed and machining accuracy.

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

[0007] An ultra-high-speed drilling air-bearing electric spindle with high-efficiency cooling includes a housing, a radial air-bearing bearing disposed within the housing, a spindle disposed within the radial air-bearing bearing, a tool assembly disposed at the front end of the spindle, a dynamic seal assembly disposed at the rear end of the spindle, a thrust air-bearing bearing disposed at the front end of the radial air-bearing bearing, a high-speed motor disposed at the rear end of the radial air-bearing bearing, a front cover, a rear cover, and a cooling air 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, radial air-bearing bearing bushes, and thrust air-bearing bearing thrust plates; the internal cooling channel is used to cool the spindle core, motor rotor, radial air-bearing bearing journals, thrust air-bearing bearing thrust plates, tool assembly, and drilling operations; the dynamic seal assembly is used to achieve a reliable seal between the high-speed spindle and the inner hole of the rear cover.

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

[0009] Furthermore, the rear end cover is provided with a bearing working gas inlet, an external cooling air inlet, and an exhaust port; the cooling air supply sleeve is provided with an internal cooling air inlet; and the tool working surface is provided with several cooling air outlets. The bearing working gas inlet, external cooling air inlet, and internal cooling air inlet are all connected to an external air supply source for introducing compressed air; the exhaust port is connected to the outside for discharging the bearing working gas and external cooling air; and the tool working surface cooling air outlets are used to spray cooling air into the machining area.

[0010] Furthermore, the housing is provided with a bearing working gas inlet channel, an external cooling air inlet channel, and an exhaust channel. One end of the bearing working gas inlet channel is connected to the bearing working gas inlet, and the other end is completely blocked; one end of the external cooling air inlet channel is connected to the external cooling air inlet, and the other end is completely blocked; one end of the exhaust channel is connected to the exhaust port, and the other end is completely blocked.

[0011] Furthermore, the radial air bearing comprises two parts: a radial bearing bush and a radial bearing journal, primarily providing radial load-bearing capacity and radial stiffness to the main shaft. The radial bearing bush is housed within the housing, and the radial bearing journal is located within the radial bearing bush, forming a section of the main shaft. Two sets of radial throttling orifices are provided on the working surface of the radial bearing bush, separated by an inner pressure relief exhaust ring groove, and symmetrically arranged on their front and rear sides. Each set of radial throttling orifices has several rows of orifices arranged axially from front to back, with each row containing several radial throttling orifices evenly distributed circumferentially. The radial throttling orifices are connected to the bearing working gas intake channel through corresponding inner air inlet holes, air inlet ring grooves, and outer air inlet holes. When the working gas of the radial air bearing is discharged, it flows sequentially through the inner pressure relief exhaust ring groove, inner exhaust hole, outer exhaust ring groove, outer exhaust hole, and exhaust channel, finally being discharged to the outside.

[0012] Furthermore, the thrust air bearing consists of two thrust pads (front and rear) and a thrust plate, located at the front end of the radial air bearing, primarily providing axial load and axial stiffness to the main shaft. The front and rear thrust pads are housed within a housing, symmetrically arranged on either side of the adjusting ring, separated by the adjusting ring. The thrust plate is fixed to the main shaft and positioned between the front and rear thrust pads. Several axial throttling orifices are evenly distributed along the circumference on the working surfaces of both the front and rear thrust pads. Specifically, the axial throttling orifices on the front thrust pad connect sequentially to the bearing's working gas intake channel via an inner air inlet, an air inlet ring groove, and an outer air inlet on the front end cover; the axial throttling orifices on the rear thrust pad connect sequentially to the inner air inlet on the radial air bearing bush via an inner air inlet, an air inlet ring groove, and an outer air inlet; when the working gas of the thrust air bearing is discharged, it sequentially passes through an inner exhaust hole, an exhaust ring groove, an outer exhaust hole, and an exhaust channel, ultimately being discharged to the outside.

[0013] Preferably, the tool assembly includes a tool and a tool holder; wherein, the tool has a plurality of internal cooling through holes and a cooling air outlet on its working surface; the tool holder is 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.

[0014] Preferably, the high-speed motor is 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.

[0015] 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 air enters through an external cooling air inlet, passes through a common external cooling air intake channel and corresponding air inlets, flows through the first to fourth external cooling channels, and finally exits to the outside through corresponding exhaust ports and a common exhaust channel. 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 radial air bearing bush; and the fourth external cooling channel is used to cool the thrust bearing thrust bush.

[0016] Furthermore, a double-helix cooling groove is provided on the outer circular surface of the motor stator cooling sleeve, and an air inlet and an exhaust hole 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 external cooling air intake channel through the corresponding air inlet, and the end is connected to the exhaust channel through the corresponding exhaust hole, which constitutes the first external cooling channel.

[0017] Furthermore, the front and rear ends of the motor stator cooling sleeve are respectively provided with an air inlet and an exhaust outlet. The air inlet is connected to an external cooling air intake channel, and the exhaust outlet is connected to an exhaust channel. The cooling air flowing out from the front air inlet passes through the gap between the stator core and the stator winding, and is then discharged from the rear exhaust outlet, which constitutes the second external cooling channel.

[0018] Furthermore, on the outer circular surface of the radial air bearing bush separated by the inner pressure relief exhaust ring groove, there is an external cooling ring groove between every two adjacent rows of radial throttling holes. The upper end of this external cooling ring groove is connected to the external cooling air intake channel through a corresponding air inlet, and the lower end is connected to the exhaust channel through a corresponding exhaust hole, thus forming a third external cooling channel.

[0019] Furthermore, an external cooling ring groove is provided on the outer circumferential surface of both the front and rear thrust bearings of the thrust air bearing. The upper end of the external cooling ring groove is connected to the external cooling air intake channel through a corresponding air inlet hole, and the lower end is connected to the exhaust channel through a corresponding exhaust hole, thus forming a fourth external cooling channel.

[0020] 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. Cooling air flows in through the internal cooling air 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 radial air bearing journal; the third internal cooling channel is used to cool the thrust plate of the thrust air bearing and the spindle core; and the fourth internal cooling channel is used to cool the tool assembly and, in the drilling process, plays a role in cooling the workpiece and in chip breaking and removal.

[0021] Furthermore, the first internal cooling channel is disposed inside the motor rotor 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.

[0022] Furthermore, the second internal cooling channel is disposed inside the radial air bearing journal 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.

[0023] Furthermore, the third internal cooling channel is located inside the thrust plate of the thrust air bearing 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.

[0024] Furthermore, the fourth internal cooling channel is disposed inside the tool assembly and extends along the axial direction of 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 cooling air outlet of the tool working surface.

[0025] Furthermore, the dynamic sealing assembly consists of a spindle end section and a rear end cover center hole. It seals the cooling air supply cup within the cooling air and maintains it at high pressure, preventing leakage of cooling air to the motor end along the sealing gap between the outer cylindrical surface of the spindle end and the inner cylindrical surface of the rear end cover center hole. The rear end cover center hole has a smooth inner cylindrical surface, and the outer cylindrical surface of the spindle end section is machined with several spiral microgrooves of a certain length (non-axially continuous). These spiral microgrooves divide the outer cylindrical surface into three regions: a groove area, a platform area, and a dam area. When the spindle rotates at high speed, the spiral microgrooves generate a dynamic pressure effect and a pumping effect in the platform area, pushing air from the motor side along the sealing gap from front to back to the dam area, creating a high-pressure sealing effect in the dam area, thus achieving a dynamic seal.

[0026] Preferably, the radius gap (i.e., sealing gap) formed by the smooth inner cylindrical surface of the center hole of the rear end cover of the dynamic sealing assembly and the dam area of ​​the outer cylindrical surface of the end shaft section of the main shaft is tens of micrometers. The depth of the spiral microgroove is twice the radius gap. The length of the dam area accounts for 1 / 3 of the length of the sealing shaft section at the end of the main shaft. The inclination direction of the spiral microgroove must be strictly matched with the rotation direction of the main shaft so that external air can be pumped from the groove area to the dam area.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention, on the one hand, cools the motor stator core, motor stator windings, radial air bearing bushes, and thrust air bearing thrust plates through the first to fourth external cooling channels; on the other hand, it cools the spindle core, radial air bearing journals, thrust air bearing thrust plates, and tool assemblies through the first to fourth internal cooling channels. The internal and external cooling methods effectively control the temperature rise of the entire electric spindle, improving its rotational accuracy and service life. Simultaneously, the internal cooling air ejected from the cooling air outlet on the tool's working surface also cools the workpiece and facilitates chip breaking and removal during the drilling process.

[0029] 2. This invention ingeniously utilizes the dynamic pressure effect and pumping effect generated by the dynamic pressure spiral microgroove when the spindle rotates at high speed to achieve a reliable seal between the high-speed spindle and the inner hole of the rear end cover, solving the dynamic sealing problem of high-pressure internal cooling air supply under high-speed operating conditions.

[0030] 3. The cooling medium introduced into the internal and external cooling channels of this invention is cooling air, which makes full use of the high-pressure air source and greatly simplifies the peripheral auxiliary devices of the electric spindle; moreover, the bearing working gas and the external cooling air do not share the same air intake channel, ensuring the high pressure and cleanliness of the working gas of the air bearing. Attached Figure Description

[0031] Figure 1 This is a schematic cross-sectional view of the high-efficiency cooling ultra-high-speed drilling air-floating electric spindle of the present invention.

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

[0033] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure at point BB.

[0034] Figure 4 This is a schematic diagram of the double-helix cooling groove structure of the motor stator cooling sleeve of the present invention.

[0035] Figure 5 This is a schematic diagram of the tool assembly structure of the present invention.

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

[0037] Explanation of reference numerals in the attached drawings: 1-House, 101-Bearing working gas inlet channel, 102-External cooling air inlet channel, 103-Exhaust channel, 104-First external cooling channel inlet, 105-Second external cooling channel external inlet, 106-109-Third external cooling channel first to fourth inlet, 110-111-Fourth external cooling channel first to second inlet, 112-117-Radial bearing first to sixth external inlet, 118-First external cooling channel exhaust, 119-Second external cooling channel exhaust, 120-123-Third external cooling channel first to fourth exhaust, 124-125-Fourth external cooling channel first to second exhaust, 126-1 27 - Radial bearing first to second external vent holes, 128 - Thrust bearing external vent hole, 2 - Main shaft, 201 - Main shaft center through hole, 3 - Radial air bearing, 301 - Radial bearing bush, 302 - Radial bearing journal, 303 to 308 - Radial bearing first to sixth internal air inlets, 309 to 314 - Radial bearing first to sixth air inlet ring grooves, 315 to 318 - Third external cooling channel first to fourth cooling ring grooves, 319 to 320 - Radial bearing first to second internal pressure relief vent ring grooves, 321 to 322 - Radial bearing first to second external vent ring grooves, 323 to 324 - Radial bearing first to second internal vent holes, 325 - Thrust bearing second external air inlet hole, 326 - Radial throttling orifice, 32 7-Radial bearing seal ring, 4-Thrust air bearing, 401-Front thrust bearing, 402-Rear thrust bearing, 403-Thrust plate, 404-Adjusting ring, 405-406-First to second cooling ring grooves of the fourth cooling channel, 407-408-First to second air inlet ring grooves of the thrust bearing, 409-410-First to second inner air inlet holes of the thrust bearing, 411-Inner exhaust hole of the thrust bearing, 412-Axial throttling orifice, 413-Exhaust 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-The first 50403 - Air inlet in the second external cooling channel, 6 - Tool assembly, 601 - Drill bit, 602 - Tool holder, 603 - Internal cooling through hole in the drill bit, 604 - Internal cooling through hole in the tool holder, 605 - Cooling air outlet on the tool surface, 7 - Dynamic seal assembly, 701 - Groove area, 702 - Platform area, 703 - Dam area, 8 - External cooling channel, 9 - Internal cooling channel, 10 - Front end cover, 1001 - First external air inlet of the thrust bearing, 11 - Rear end cover, 1101 - Bearing working gas inlet, 1102 - External cooling air inlet, 1103 - Exhaust port, 1104 - Center hole of the rear end cover, 12 - Internal cooling air supply sleeve, 1201 - Internal cooling air 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 3 This invention discloses a high-efficiency cooling ultra-high-speed drilling air-bearing electric spindle, comprising a housing 1, a spindle 2, a radial air bearing 3, a thrust air bearing 4, a high-speed permanent magnet synchronous motor 5, a tool assembly 6, a dynamic sealing assembly 7 at the spindle end, a front cover 10, a rear cover 11, and an internal cooling air 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 radial air bearing 3 and the thrust air bearing 4, and has a hollow structure with a through hole 201 in the center for connecting cooling air. The rear cover 11 is provided with a bearing working gas inlet 1101, an external cooling air inlet 1102, and an exhaust port 1103; the cooling air supply sleeve 12 is provided with an internal cooling air inlet 1201; and a plurality of cooling air outlets 605 are provided on the working surface of the drill bit 601. The bearing working gas inlet 1101, external cooling air inlet 1102, and internal cooling air inlet 1201 are all connected to an external air supply source for introducing compressed air; the exhaust port 1103 is connected to the outside and is used to discharge the bearing working gas and external cooling air; the drill bit surface cooling air outlet 605 is used to spray cooling air onto the machining area. The housing 1 is equipped with a bearing working gas inlet channel 101, an external cooling air inlet channel 102, and an exhaust channel 103; one end of the bearing working gas inlet channel 101 is connected to the bearing working gas inlet 1101, one end of the external cooling air inlet channel 102 is connected to the external cooling air inlet 1102, and one end of the exhaust channel 103 is connected to the exhaust port 1103; the other ends of all three are completely sealed.

[0040] See Figure 1 and Figure 3The radial air 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 the first inner pressure relief exhaust ring groove 319 of the radial bearing, and symmetrically arranged on its front and rear sides. Each set of radial throttling orifices has three rows arranged axially from front to back, and each row has several radial throttling orifices 326, evenly arranged circumferentially. The radial throttling orifices 326 are connected to the bearing working gas intake channel 101 through the corresponding first to sixth inner air inlets (303 to 308), the first to sixth air inlet ring grooves (309 to 314), and the first to sixth outer air inlets (112 to 117), respectively. The inner circular surface of the radial bearing bush 301 is provided with the first (319) and second (320) inner pressure relief and exhaust ring grooves of the radial bearing. When the working gas of the radial and thrust air bearings is discharged, it flows through the first and second inner pressure relief and exhaust ring grooves (319 and 320) of the radial bearing, the first and second inner exhaust holes (323 and 324) of the radial bearing, the first and second outer exhaust ring grooves (321 and 322) of the radial bearing, the first and second outer exhaust holes (126 and 127) of the radial bearing, and the exhaust channel 103, and finally is discharged to the outside. The outer circumference of the radial bearing bush 301 is provided with the first to fourth cooling ring grooves (315 to 318) of the third external cooling channel, and radial bearing seals 327 are installed on both sides of each cooling ring groove. The upper ends of the first to fourth cooling ring grooves (315 to 318) of the third external cooling channel are connected to the external cooling air intake channel 102 through the first to fourth air inlets (106 to 109) of the third external cooling channel, and the lower ends are connected to the exhaust channel 103 through the first to fourth exhaust holes (120 to 123) of the third external cooling channel.

[0041] See Figure 1 and Figure 3The thrust air bearing 4 is located at the front end of the radial air bearing 3 and consists of a front thrust bearing 401, a rear thrust bearing 402 and a thrust plate 403; wherein, the front thrust bearing 401 and the rear thrust bearing 402 are separated by an adjusting ring 404; the thrust plate 403 is fixedly connected to 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 on their working surfaces, which are evenly distributed along the circumference. The axial throttling holes 412 on the front thrust bearing 401 are connected to the bearing working gas intake channel 101 through the first inner air inlet hole 409, the first air inlet ring groove 407, and the first outer air inlet hole 1001 on the front end cover 10. The axial throttling holes 412 on the rear thrust bearing 402 are connected to the first inner air inlet hole 303 of the radial bearing through the second inner air inlet hole 410, the second air inlet ring groove 408, and the second outer air inlet hole 325. When some of the working gas of the thrust bearing is discharged, it is discharged to the outside through the inner exhaust hole 411, the exhaust ring groove 413, the outer exhaust hole 128, and the exhaust channel 103. 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, and the thrust bearing seal ring 414 is installed on both sides of each cooling ring groove. The upper ends of the first (405) and the second (406) cooling ring grooves of the fourth external cooling channel are connected to the external cooling air intake channel 102 through the first (110) and the second (111) air inlets of the fourth external cooling channel, respectively, and the lower ends are connected to the exhaust channel 103 through the first (124) and the second (125) exhaust holes of the fourth external cooling channel, respectively.

[0042] See Figures 1 to 4 The high-speed permanent magnet synchronous motor 5 is located at the rear end of the radial air 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 external cooling air intake channel 102 through the first external cooling channel air inlet 104, and the end is connected to the exhaust channel 103 through the first external cooling channel exhaust port 118. The front and rear ends of the motor stator cooling sleeve 504 are respectively provided with a second external cooling channel air inlet 50402 and a second external cooling channel exhaust port 50403.

[0043] See Figure 1 and Figure 5The tool assembly 6 consists of a drill bit 601 and a tool holder 602. The drill bit 601 has several internal cooling through holes 603 and several cooling air outlets 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 drill bit 601 is clamped in the tool holder 602 using heat-shrink fittings.

[0044] See Figure 1 and Figure 6 The dynamic sealing assembly 7 is located at the end of the main shaft 2 and consists of the end shaft section of the main shaft and the central hole 1104 of the rear end cover. A non-axially continuous spiral microgroove is machined on the outer cylindrical surface of the end shaft section, dividing the outer cylindrical surface into three regions: a groove region 701, a platform region 702, and a dam region 703. The depth of the spiral microgroove is comparable to the sealing gap, which is several tens of micrometers. When the main shaft 2 rotates at high speed, the spiral microgroove generates a dynamic pressure effect and a pumping effect in the platform region, pushing air along the sealing gap from front to back to the dam region 703, forming a high-pressure sealing pressure in the dam region. This pressure then serves to supply high-pressure cooling air to the sleeve cup 12.

[0045] See Figure 1 and Figure 3The 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 air enters the external cooling air intake channel 102 from an external air source through the external cooling air inlet 1102; simultaneously, the external cooling air flowing into the exhaust channel 103 and the bearing working gas are finally discharged to the outside through the exhaust port 1103. Firstly, the cooling air in the external cooling air intake channel 102 flows into the double spiral cooling groove 50401 on the motor stator cooling jacket 504 through the first external cooling channel inlet 104, and then flows into the exhaust channel 103 through the first external cooling channel exhaust port 118, thereby cooling the motor stator core 501, which constitutes the first external cooling channel. Secondly, the cooling air in the external cooling air intake channel 102 flows sequentially through the second external cooling channel outer air intake hole 105 and the second external cooling channel inner air intake hole 50402, into the gap between the motor stator core 501 and the motor stator winding 502, and then sequentially through the second external cooling channel inner exhaust hole 50403 and the second external cooling channel outer exhaust hole 119, into the exhaust channel 103, thereby cooling the motor stator winding 502. This constitutes the second external cooling channel. Thirdly, the cooling air in the external cooling air intake channel 102 flows sequentially through the first to fourth air intake holes (106 to 109) of the third external cooling channel, into the first to fourth cooling ring grooves (315 to 318) of the third external cooling channel, and then flows sequentially through the first to fourth exhaust holes (120 to 123) of the third external cooling channel into the exhaust channel 103, thereby cooling the radial bearing bush 301. This constitutes the third external cooling channel. Fourth, the cooling air in the external cooling air intake 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 air intake holes (110 and 111) of the fourth external cooling channel, and then flows into the exhaust channel 103 through the first and second exhaust holes (124 and 125) 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 1The 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. Cooling air enters from an external air source into the cooling air supply cup 12 through the internal cooling air 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 the motor rotor 503 and extends along the axial direction of the spindle center through hole 201. One end of the channel is connected to the end inlet of the spindle center through hole 201, and the other end is connected 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 radial air bearing journal 302 and extends along the axial direction of the spindle center through hole 201. One end of the channel is connected to the first internal cooling channel, and the other end is connected to the third internal cooling channel, used to cool the radial air bearing journal 302. Thirdly, the third internal cooling channel is located inside the thrust gas... The thrust bearing thrust plate 403 is located inside the spindle section and extends along the axis of the spindle center through hole 201. 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. This channel is used to cool 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 602 and the drill bit 601. One end of the channel is connected to the third internal cooling channel, and the other end is connected to the cooling air outlet 605 on the working surface of the drill bit. This channel is used not only to cool the tool assembly but also to cool the workpiece and break and remove chips during drilling.

[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-efficiency cooling ultra-high-speed drilling air-floating electric spindle, characterized in that: The electric spindle includes a housing (1), a radial air bearing (3) disposed in the housing, a spindle (2) disposed in the radial air bearing (3), a tool assembly (6) disposed at the front end of the spindle (2), a dynamic seal assembly (7) disposed at the end of the spindle (2), a thrust air bearing (4) disposed at the front end of the radial air bearing (3), a high-speed motor (5) disposed at the rear end of the radial air bearing (3), a front end cover (10), a rear end cover (11), and a cooling air supply sleeve (12), as well as an external cooling channel (8) and an internal cooling channel (9) disposed in the electric spindle; 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 cooling air supply cup (12) is provided with an internal cooling air inlet (1201), and the cooling air flows in from the internal cooling air inlet (1201), then passes through the first to fourth internal cooling channels in sequence, and finally reaches the drilling area; the radial air bearing (3) consists of two parts: a radial bearing bush (301) and a radial bearing journal (302), and the radial bearing journal (302) is one of the main spindles (2). A shaft section; the thrust air bearing (4) is composed of a front thrust bearing (401), a rear thrust bearing (402) and a thrust plate (403); 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 radial bearing journal (302), the third internal cooling channel is used to cool the thrust plate (403) of the thrust air bearing (4) and the spindle (2), and the fourth internal cooling channel is used to cool the tool assembly (6) and plays a role in cooling the workpiece and chip breaking and removal during drilling; The first internal cooling channel is located inside the motor rotor (503) and extends along the axial direction of the motor rotor (503) and the main shaft (2). One end of the first internal cooling channel is connected to the end inlet of the central through hole (201) of the main shaft. The second internal cooling channel is located inside the radial bearing journal (302) and extends along the axial direction of the journal. The third internal cooling channel is located inside the thrust plate (403) of the thrust air bearing (4) and extends along the axial direction of the thrust plate (403) and the main shaft (2). The tool assembly (6) consists of a drill bit (601) and a tool holder. (602) The drill bit (601) is provided with a plurality of internal cooling through holes (603) and a cooling air outlet (605) is provided on the working surface of the drill bit (601). The tool holder (602) is provided with an internal cooling through hole (604). The fourth internal cooling channel is provided inside the tool assembly (6) and extends along the axial direction of the internal cooling through hole (604) of the tool holder and the internal cooling through hole (603) of the drill bit. One end of the fourth internal cooling channel is connected to the cooling air outlet (605) on the working surface of the tool. The first to fourth internal cooling channels are connected to each other end to end. The dynamic sealing assembly (7) consists of the end shaft section of the main shaft (2) and the center hole (1104) of the rear end cover, and is used to seal the cooling air in the cooling air supply cup (12) and keep it at high pressure; wherein, a non-axially penetrating spiral micro-groove is machined on the outer cylindrical surface of the end shaft section of the main shaft (2), and the spiral micro-groove divides the outer cylindrical surface into a groove area (701), a platform area (702) and a dam area (703). When the main shaft rotates at high speed, the spiral micro-groove will produce in the groove area (701) and the platform area (702). The dynamic pressure effect and pumping effect push the outer air along the sealing gap from front to back to the dam area (703), and form a high pressure sealing pressure in the dam area (703); the sealing gap of the dynamic sealing component (7) is more than ten micrometers, the depth of the spiral microgroove is twice the sealing gap, the length of the dam area (703) accounts for 1 / 3 of the length of the entire sealing shaft section, and the inclination direction of the spiral microgroove is strictly matched with the rotation direction of the main shaft (2) so that air can be pumped from the groove area (701) and the platform area (702) to the dam area (703).

2. The high-efficiency cooling ultra-high-speed drilling air-floating electric spindle as described in claim 1, characterized in that: The spindle (2) is a hollow structure with a through hole (201) in the center for connecting cooling air; the housing (1) is provided with a bearing working gas inlet channel (101), an external cooling air inlet channel (102), and an exhaust channel (103); the rear end cover (11) is provided with a bearing working gas inlet (1101), an external cooling air inlet (1102), and an exhaust port (1103); a plurality of cooling air outlets (605) are provided on the working surface of the tool; the bearing working gas inlet (1101), the external cooling air inlet (1102), and the exhaust port (1103) are provided. The internal cooling air inlet (1201) is connected to the external air supply source for introducing compressed air; the exhaust port (1103) is connected to the outside for discharging bearing working gas and external cooling air; the tool working surface cooling air outlet (605) is used to spray cooling air into the machining area; one end of the bearing working gas inlet channel (101) is connected to the bearing working gas inlet (1101), one end of the external cooling air inlet channel (102) is connected to the external cooling air inlet (1102), and one end of the exhaust channel (103) is connected to the exhaust port (1103).

3. The high-efficiency cooling ultra-high-speed drilling air-floating electric spindle as described in claim 2, characterized in that: Both the front thrust bearing (401) and the rear thrust bearing (402) have several axial throttling holes (412) on their working surfaces, which are evenly distributed along the circumference. The axial throttling holes (412) on the front thrust bearing are connected to the bearing working gas intake channel (101) via the first inner air inlet hole (409) of the thrust bearing, the first air inlet ring groove (407) of the thrust bearing, and the first outer air inlet hole (1001) of the thrust bearing on the front end cover. The axial throttling holes (412) on the rear thrust bearing... 2) The thrust bearing (4) is connected to the radial bearing (303) on the radial bearing bush (301) in sequence through the second inner air inlet hole (410), the second air inlet ring groove (408), and the second outer air inlet hole (325) of the thrust bearing; when the working gas of the thrust air bearing (4) is discharged, it is connected to the radial bearing (303) in sequence through the inner exhaust hole (411), the exhaust ring groove (413), the outer exhaust hole (128), and the exhaust channel (103) of the thrust bearing in sequence, and finally discharged to the outside.

4. The high-efficiency cooling ultra-high-speed drilling air-floating electric spindle as described in claim 3, characterized in that: 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 air enters through an external cooling air inlet (1102), passes through a common external cooling air intake channel (102) and a corresponding air intake hole, flows through the first to fourth external cooling channels, and is finally discharged to the outside through a corresponding exhaust hole and a common exhaust channel (103); wherein, the first external cooling channel is used to cool the stator core (501) of the motor, the second external cooling channel is used to cool the stator winding (502) of the motor, the third external cooling channel is used to cool the radial bearing bush (301), and the fourth external cooling channel is used to cool the front and rear thrust bushes (401 and 402) of the thrust air bearing (4).

5. The high-efficiency cooling ultra-high-speed drilling air-floating electric spindle as described in claim 4, characterized in that: A double-spiral cooling groove (50401) is provided on the outer circular surface of the motor stator cooling sleeve (504). The starting end of the double-spiral cooling groove (50401) is connected to the external cooling air intake channel (102) through a corresponding air inlet (104), and the ending end is connected to the exhaust channel (103) through a corresponding exhaust hole (118). This is 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 (50402) and an exhaust hole (50403). The air inlet (50402) is connected to the external cooling air intake channel (102), and the exhaust hole (50403) is connected to the exhaust channel (103). The cooling air flowing out from the front air inlet (50402) passes through the gap between the stator core (501) and the stator winding (502), and is then discharged from the rear exhaust hole (50403). This is the first external cooling channel. The second external cooling channel is described above; an external cooling ring groove (315 to 318) is provided between every two adjacent rows of radial throttling holes on the outer surface of the radial bearing bush (301). The upper end of this external cooling ring groove is connected to the external cooling air intake channel (102) through the air inlet hole (106 to 109), and the lower end is connected to the exhaust channel (103) through the exhaust hole (120 to 123). This is 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 thrust air bearing (4). The upper end of the external cooling ring groove is connected to the external cooling air intake channel (102) through the corresponding air inlet hole (110 to 111), and the lower end is connected to the exhaust channel (103) through the corresponding exhaust hole (124 to 125). This is the fourth external cooling channel.

6. The high-efficiency cooling ultra-high-speed drilling air-floating electric spindle as described in claim 1, characterized in that: The tool holder (602) is a heat shrink tool holder. The tool holder (602) is installed at the front end of the spindle (2) through outer circle positioning and threaded connection. The drill bit (601) is clamped in the tool holder (602) by using heat shrink fittings.

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