Electric spindle

Abstract

The utility model relates to an electric spindle which comprises a shell and a rotating shaft, a bearing seat is installed at the front end in the shell, the rotating shaft is rotatably installed in the shell through a bearing installed in the bearing seat, a pressing nut used for pressing the bearing is further installed at the front end of the rotating shaft in a screwed mode, and the front end of the shell is further connected with a pressing cover blocking the front side of the bearing seat. The gland is provided with an inner hole allowing the rotating shaft to penetrate through and allowing the gland nut to extend into, a spiral groove is formed in one of the gland nut and the gland, and the rotating direction of the spiral groove meets the requirement that when the gland nut rotates along with the rotating shaft and rotates relative to the gland, a spiral exhaust structure exhausting air forwards is formed in the fit clearance of the gland nut and the gland. An inner cavity of the shell is communicated with the air inlet side of the rear end of the spiral groove, and an air inlet communicated with the inner cavity and the outside is formed in the shell. According to the electric spindle, water and cuttings are blocked outside the spindle under the action of airflow, the water and the cuttings are prevented from entering the interior of the spindle to damage lubrication of the spindle, and the sealing performance of the spindle is effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of spindle technology, and in particular to an electric spindle. Background Technology

[0002] With the continuous advancement of industrial automation, electric spindles are increasingly widely used in high-end manufacturing equipment. The efficient and stable operation of electric spindles has a decisive impact on the machining accuracy and production efficiency of the entire equipment. Currently, there are three main lubrication methods for electric spindles: grease lubrication, oil mist lubrication, and oil-air lubrication. Grease-lubricated electric spindles demonstrate irreplaceable advantages in low-speed, light-load, and difficult-to-use lubrication applications.

[0003] However, due to the extremely high efficiency requirements of machining, grease-lubricated electric spindles need to be cooled by water spray at the front end. Because of the large volume of water sprayed and the close proximity of the spindle front end to the machining area, traditional mechanical labyrinth seals are highly unreliable. Water and impurities generated during cutting can easily enter the electric spindle, affecting its normal operation. Therefore, it is necessary to develop more reliable sealing technology to effectively prevent moisture and impurities from entering the electric spindle, thereby ensuring the long-term stable operation and machining accuracy of grease-lubricated electric spindles.

[0004] To address the aforementioned issues, existing technologies, such as Chinese invention patent CN106958660B (authorization announcement number CN106958660B, authorization announcement date June 21, 2019), disclose a grease-lubricated electric spindle. This utility model's electric spindle features a waterproof sealing assembly between the spindle and the spindle housing, located outside the bearing assembly. The waterproof sealing assembly includes a pressure cap fixed to the end of the spindle housing, a waterproof cover fixed to the pressure cap, and a nut fitted onto the side of the spindle end. The center of the waterproof cover is clearance-fitted with the bearing, and a drain port is located below the waterproof cover. The pressure cap and nut are sealed together, and a spiral water-throwing groove is provided on the side of the nut outside the sealing area. A first drainage groove corresponding to the drain port is provided on the lower end face of the pressure cap, and the circumferential rotation path of the spiral water-throwing groove passes through the first drainage groove.

[0005] The electric spindle of this invention uses a spiral water-throwing groove to throw the cutting fluid mixed with chips through the waterproof cover out through the first drainage groove, and finally out of the spindle through the drain port below the waterproof cover. However, there is a certain gap between the outer circumferential surface of the spiral water-throwing groove on the outside of the nut and the annular baffle wall on the gland located outside the spiral water-throwing groove. The liquid in this gap cannot be discharged by the spiral water-throwing groove, and some of the cutting fluid passing through the waterproof cover still inevitably enters the spindle, thereby damaging the spindle lubrication, causing accelerated wear of the electric spindle, and thus affecting the service life and machining accuracy of the electric spindle. Utility Model Content

[0006] The purpose of this invention is to provide an electric spindle that solves the problem that the sealing structure of the existing electric spindle is unreliable, and some of the cutting fluid through the waterproof cover still inevitably enters the spindle, thereby damaging the spindle lubrication, causing the electric spindle to wear more quickly, and thus affecting the service life and machining accuracy of the electric spindle.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0008] The electric spindle of this utility model includes a housing and a rotating shaft. A front bearing seat is installed at the front end of the housing. The rotating shaft is rotatably mounted in the housing through the front bearing installed in the front bearing seat. A clamping nut for clamping the front bearing is screwed onto the front end of the rotating shaft. A pressure cap is also connected to the front end of the housing and is blocked on the front side of the front bearing seat. The pressure cap has an inner hole for the rotating shaft to pass through and for the clamping nut to extend into. One of the clamping nut and the pressure cap is provided with a spiral groove. The direction of the spiral groove is such that when the clamping nut rotates with the rotating shaft and rotates relative to the pressure cap, a spiral exhaust structure for forward exhaust is formed at the mating gap between the clamping nut and the pressure cap. The inner cavity of the housing is connected to the rear air inlet side of the spiral groove. An air inlet is provided on the housing to connect the inner cavity with the outside.

[0009] Furthermore, an air filter is connected to the air inlet on the housing.

[0010] Furthermore, the housing includes a cylindrical housing and a rear cover disposed at the rear end of the cylindrical housing, with an air inlet disposed on the housing located on the rear cover.

[0011] Furthermore, the air intake is located in the center of the rear cover, and a quick connector is also provided at the air intake, which connects to the air filter through the air intake pipe.

[0012] Furthermore, the air passage between the air inlet and the rear air inlet side of the spiral groove includes an axial air passage disposed within the rotating shaft and a radial air passage at the front end of the axial air passage. The rear end of the axial air passage is connected to the air inlet, and the outer end of the radial air passage is connected to the inner cavity of the housing. The air passage also includes an axially penetrating bearing housing air passage disposed on the front bearing housing. The gas entering from the air inlet passes through the axial air passage, the radial air passage, the inner cavity of the housing, and the bearing housing air passage to the rear air inlet side of the spiral groove.

[0013] Furthermore, the gland includes an annular cover body and a rearwardly extending axial protrusion ring located in the middle of the annular cover body. The axial protrusion ring blocks the front side of the front bearing. The axial protrusion ring is provided with a radially penetrating protrusion ring channel. The bearing housing air passage is connected to the rear air intake side of the spiral groove through the protrusion ring channel.

[0014] Furthermore, the housing includes a cylindrical housing and a rear cover located at the rear end of the cylindrical housing. A rear bearing seat is provided at the rear end of the inner cavity of the cylindrical housing. The rear bearing seat is axially floatingly installed inside the cylindrical housing and connected to a spring baffle at the rear end. A floating spring that provides preload force to the rear bearing is provided between the spring baffle and the cylindrical housing. An air guide pipe with both ends sealed and slidably inserted into the rear cover and the spring baffle is also provided between the rear cover and the spring baffle. The gas entering through the air inlet enters the axial air passage through the air guide pipe.

[0015] Furthermore, the compression nut has an outer flange that protrudes radially outward on the front side of the gland, and the outer flange and the front side of the gland are fitted together by an annular convex and an annular groove to form a folded sealing structure.

[0016] Furthermore, a dust cover is connected to the front end of the housing. The front end of the rotating shaft passes through the middle of the dust cover, and a gap for gas to be discharged is formed between the dust cover and the rotating shaft. The dust cover is fastened to the front end of the housing and covers the clamping nut and the pressure cap. The part of the inner side of the dust cover that is close to the clamping nut in the axial direction is the nut covering surface. The nut covering surface and the front end face of the clamping nut are connected by an annular convex and an annular groove to form a folded sealing structure.

[0017] Furthermore, the inner side of the dust cover, which is close to the gland in the axial direction, is the gland cover shielding surface. The gland cover shielding surface is located behind the nut shielding surface, and there is an axial transition surface between the two. A drainage hole is also provided on the lower side of the dust cover at the location corresponding to the axial transition surface.

[0018] This invention innovatively proposes an electric spindle. The electric spindle has a clamping nut and a pressure cap at its front end. A spiral groove is provided on one of the clamping nut and the pressure cap. The direction of the spiral groove is such that when the clamping nut rotates with the spindle and rotates relative to the pressure cap, a forward-venting spiral exhaust structure is formed at the mating gap between the clamping nut and the pressure cap. This spiral exhaust structure acts as an air pump, creating a constantly venting environment at the gap between the clamping nut and the pressure cap at the front end of the spindle during operation. Through the airflow, water and chips at one end of the spindle's machining area are blocked from entering the spindle, preventing them from damaging the spindle's lubrication. This provides a more reliable sealing effect and effectively solves the problem of unreliable sealing structures in existing electric spindles, where some cutting fluid still inevitably enters the spindle through the waterproof cover, damaging the spindle's lubrication, leading to accelerated wear, and ultimately affecting the spindle's service life and machining accuracy. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of one embodiment of the electric spindle of this utility model;

[0020] Figure 2 for Figure 1 Sectional view at AA;

[0021] Figure 3 for Figure 1 A magnified view of a section at point B;

[0022] Figure 4 for Figure 3 A magnified view of point C;

[0023] Figure 5 This is a schematic diagram of the dust cover structure of one embodiment of the electric spindle of this utility model;

[0024] Figure 6 This is a schematic diagram of the gland structure of one embodiment of the electric spindle of this utility model;

[0025] Figure 7 This is a cross-sectional view of the nut structure of an embodiment of the electric spindle of this utility model.

[0026] In the diagram: 1. Dust cover; 2. Pressure cap; 3. Compression nut; 4. Front outer spacer; 5. Front inner spacer; 6. Front bearing housing; 7. Front cover; 8. Cylindrical housing; 9. Shaft; 10. Rotor; 11. Stator; 12. Rear bearing housing; 13. Sliding bearing; 14. Rear outer spacer; 15. Rear inner spacer; 16. Housing bushing; 17. Floating spring; 18. Rear nut; 19. Spring baffle; 20. Rear cover; 21. Air duct; 22. Quick connector; 23. Air inlet pipe; 24. Air filter; 25. Power connector; 104. Axial air passage of shaft; 105. Radial air passage of shaft; 109. Housing cavity; 110. Air passage of bearing housing; 112. Pressure cap notch; 114. First annular ring. Cavity; 115. Spiral exhaust structure; 116. First annular gap; 117. Second annular gap; 118. Third annular gap; 119. Hollow cavity; 120. Fourth annular gap; 121. Fifth annular gap; 122. Sixth annular gap; 123. Seventh annular gap; 201. First tortuous circuit; 202. Second tortuous circuit; 1001. Dust cover rear end protrusion; 1002. Drain hole; 2001. First convex ring; 2002. Second convex ring; 2003. Pressure cap front end protrusion; 2004. Spiral groove; 3001. Pressure nut rear end groove; 3002. Pressure nut front end recess; 3003. Pressure nut outer peripheral surface; 3004. Pressure nut rear end face; 3005. Outer flange. Detailed Implementation

[0027] The features and performance of this utility model will be further described in detail below with reference to the embodiments.

[0028] The electric spindle of this invention features a spiral groove at the mating position of the clamping nut and the pressure cap. During operation, the high-speed relative rotation between the clamping nut and the pressure cap creates a spiral exhaust structure through the spiral groove, which acts as an air pump. This ensures that the clamping nut and the pressure cap are always in a state of outward exhaust. In this way, the airflow prevents external debris from entering the electric spindle through the mating gap between the clamping nut and the pressure cap, thus ensuring a reliable seal for the electric spindle.

[0029] Based on the above concept, this utility model provides various embodiments of the electric spindle for illustration.

[0030] In a basic embodiment, such as Figure 1 , Figure 3 , Figure 4 The electric spindle shown includes a housing and a rotating shaft 9. The housing includes a front cover 7, a cylindrical housing 8, and a rear cover 20. A stator 11 is installed inside the cylindrical housing, and a rotor 10 is installed on the rotating shaft. A front bearing housing is installed at the front end of the housing, and a rear bearing housing is installed at the rear end. The rotating shaft 9 is rotatably mounted inside the housing via the front and rear bearings installed in the front and rear bearing housings. A power connector 25 is also provided on the rear cover 20, and the power connector 25 is connected to the stator leads.

[0031] The front end of the rotating shaft 9 is screwed with a clamping nut 3 for engaging with the shoulder on the rear side of the front bearing to press the front bearing. The front bearings are arranged in pairs, and a front outer spacer 4 and a front inner spacer 5 are provided between the two front bearings. The front end of the rotating shaft 9 extends out of the housing and serves as the power output end. The front end of the housing is also connected to a cover 2 that blocks the front side of the front bearing seat 6. The cover 2 is fitted over the outside of the clamping nut 3. The clamping nut and the cover have a helical groove on one of their radially opposite outer and inner circumferential surfaces. The direction of the helix of the helical groove is such that when the clamping nut 3 rotates with the rotating shaft 9 and rotates relative to the cover 2, a forward-venting helical exhaust structure is formed at the mating gap between the clamping nut 3 and the cover 2. The rear intake side of the spiral exhaust structure is directly or indirectly connected to the external environment. Thus, when the electric spindle is working, the spiral exhaust structure acts as an air pump, which can draw air from outside the electric spindle so that the mating gap between the clamping nut 3 and the pressure cover 2 is always in an environment of outward exhaust. In this way, the working debris at the front end of the shaft will not enter the electric spindle through the mating gap between the clamping nut 3 and the pressure cover 2, thus achieving a reliable sealing effect.

[0032] Based on the above embodiments, there are many ways to achieve communication between the rear air intake side of the spiral exhaust structure and the external environment. In one embodiment, a radially penetrating through hole is opened on the cylindrical shell 8 to achieve communication between the inner cavity of the shell and the outside. A channel is set on the front bearing seat, the cover or the rotating shaft. It is only necessary to ensure that when the spiral exhaust structure is pumping air, the air can enter the inner cavity of the shell through the through hole and flow to the rear air intake side of the spiral exhaust structure.

[0033] In a preferred embodiment, such as Figure 1 As shown, the air inlet on the housing is located on the rear cover 20. The air passage between the air inlet and the rear air intake side of the spiral exhaust structure includes an axial air passage 104 within the rotating shaft 9 and a radial air passage 105 at the front end of the axial air passage 104. The radial air passage is radially connected to the inner cavity 109 of the housing. Preferably, as shown... Figure 2 As shown, four radial air passages are provided on the spindle. The rear end of the axial air passage 104 is connected to the air inlet. The outer end of the radial air passage 105 is connected to the inner cavity 109 of the housing. The air passage also includes an axially penetrating bearing housing air passage 110 provided on the front bearing housing 6. The gas entering from the air inlet passes through the axial air passage 104, the radial air passage 105, the inner cavity 109 of the housing, and the bearing housing air passage 110 to the rear air inlet side of the spiral groove 2004. This arrangement allows the gas passage to flow through the electric spindle axially as a whole, which can carry away the heat generated when the cold air from the outside passes through the inside of the electric spindle, thereby playing a cooling role.

[0034] The gland includes an annular cover and a rearwardly extending axial protruding ring located in the middle of the annular cover. The axial protruding ring includes a first protruding ring 2001 and a second protruding ring 2002 located on the end face of the first protruding ring. The second protruding ring 2002 is disposed close to the outer ring of the front bearing. The second protruding ring 2002 has a radially penetrating gland notch 112 to allow radially outer gas to enter the interior through the gland notch 112. A first annular cavity 114 is formed at the fitting gap between the end face of the first protruding ring 2001 and the front bearing. Gas flows from the bearing housing air passage through the gland notch 112 and the first annular cavity 114 to the rear air intake side of the spiral exhaust structure. The rear end face 3004 of the clamping nut 3 is in close contact with the front bearing.

[0035] Based on the above embodiment, a sliding bearing 13 is installed at the rear end of the cylindrical housing 8 via a housing bushing 16. A rear bearing seat 12 is axially floating within the cylindrical housing 8 via the sliding bearing 13. A pair of rear bearings are installed within the rear bearing seat 12. A rear nut 18 is installed on the shaft behind the rear bearings, engaging with the shoulder on the front side of the rear bearing to press it into a defined position. An outer rear spacer 14 and an inner rear spacer 15 are installed between the two rear bearings. A spring baffle 19 is connected to the rear end of the rear bearing seat. A floating spring 17, which pushes the rear bearing seat 12 backward, is provided between the spring baffle 19 and the cylindrical housing 8 to provide a rearward preload to the rear bearing. A through hole is provided on the spring baffle 19 at a position corresponding to the axial air passage of the shaft, allowing air entering from the air inlet of the rear cover to pass through the through hole into the axial air passage of the shaft. In an optimized embodiment, an air guide pipe 21 is also provided between the rear cover and the spring baffle, with both ends sealed and slidably inserted into the rear cover and the spring baffle respectively. The gas entering through the air inlet enters the axial air passage through the air guide pipe 21.

[0036] Based on the above embodiments, in an optimized embodiment, an air filter 24 is further provided at the air inlet to ensure that the gas entering the electric spindle is relatively clean and to prevent impurities from entering the electric spindle. In a preferred embodiment, such as Figure 1 As shown, the air inlet is located at the center of the rear cover 20. A quick connector 22 is also provided at the air inlet. The quick connector 22 is connected to the air filter 24 through the air inlet pipe 23. This ensures that the incoming air will not be mixed with any impurities and enter the interior of the electric spindle.

[0037] Based on the above embodiments, in one embodiment, the outer diameter of the clamping nut is equal to the inner diameter of the gland. In another optimized embodiment, the clamping nut has an outer flange that protrudes radially outward on the front side of the gland, and the outer flange and the front side of the gland are fitted together by an annular convex and an annular groove to form a folded-back sealing structure. Figure 3 , 4 As shown in Figures 6 and 7, the front end face of the pressure cap 2 is provided with a pressure cap front end protrusion 2003, and the outer flange 3005 of the clamping nut 3 is provided with a clamping nut rear end groove 3001. This forms a folded sealing structure between the front end of the pressure cap 2 and the rear end of the clamping nut 3 through the annular protrusion and annular groove. The first zigzag circuit 201 formed at the mating gap includes a radial first annular gap 116, an axial second annular gap 117, and a radial third annular gap 118 connected end-to-end. The size of the first annular gap 116 can be adjusted by cutting the outer circumferential surface of the clamping nut 3.

[0038] Based on the above embodiment, in the axial mating section of the pressure cap 2 and the clamping nut 3, a spiral groove is provided on the mating surface of one of them, forming a spiral venting gap 115 at the mating clearance. Figure 6 , Figure 7 In the embodiment shown, a spiral groove 2004 is provided on the pressure cap 2, and the outer peripheral surface 3003 of the pressure nut 3 on the axial direction is set as a smooth surface. A spiral exhaust structure 115 is formed at the fitting gap. The spiral exhaust structure 115 is connected to the first annular cavity 114 and the first tortuous circuit 201. After the rotating shaft 9 drives the pressure nut 3 to rotate, it generates a spiral force on the air, forming an outward high-pressure airflow. The high-pressure airflow is discharged outward through the annular cavity to achieve a sealing effect.

[0039] Based on the above embodiments, the front end of the electric spindle is sealed by the fit between the clamping nut 3 and the pressure cap 2. In a preferred embodiment, such as... Figure 1 As shown, a dust cover 1 is also connected to the front end of the housing to prevent impurities at the front end of the electric spindle from entering the interior of the electric spindle. The front end of the rotating shaft 9 extends through the middle of the dust cover 1, and a seventh annular gap 123 for gas discharge is formed between the dust cover 1 and the rotating shaft 9. The dust cover 1 is fastened to the front end of the housing and covers the clamping nut 3 and the pressure cap 2. The part of the inner side of the dust cover 1 that is close to the clamping nut 3 in the axial direction is the nut covering surface. The nut covering surface and the front end face of the clamping nut are connected by an annular convex and an annular groove to form a folded sealing structure.

[0040] like Figure 3 , 4 As shown in Figures 5 and 7, the front end of the clamping nut 3 is provided with a clamping nut front end recess 3002, and the nut shielding surface of the dust cover 1 is provided with a dust cover rear end protrusion 1001, thereby forming a concave-convex fit between the dust cover 1 and the clamping nut 3. The second tortuous loop 202 formed at the fit gap includes a radial fourth annular gap 120, an axial fifth annular gap 121 and a radial sixth annular gap 122 that are connected end to end. The sixth annular gap 122 and the seventh annular gap 123 are connected.

[0041] The inner surface of the dust cover 1, which is close to the pressure cap 2 in the axial direction, is the pressure cap shielding surface. The pressure cap shielding surface is located behind the nut shielding surface, and there is an axial transition surface between the two. The axial transition surface is a conical surface, thus forming a cavity 119 between the dust cover 1, the pressure cap 2, and the clamping nut 3. The front end of the cavity 119 is connected to the first zigzag circuit 201, and the rear end is connected to the second zigzag circuit 202. A drain hole 1002 is also provided on the lower side of the dust cover at the location corresponding to the axial transition surface to drain water and chips blocked by gas.

[0042] During operation, under the pumping action of the spiral exhaust structure, outside air enters the intake pipe 23 through the air filter 12, and then enters the air passage inside the grease-lubricated electric spindle through the quick connector 22. The air then flows through the air passage to the spiral exhaust structure 115, forming an outward high-pressure airflow. This high-pressure airflow is discharged outward through the first bend circuit 201 and the second bend circuit 202, achieving a sealing effect. Simultaneously, the outside air passing through the entire electric spindle can also carry away the heat generated inside the spindle during operation, providing a certain cooling effect.

[0043] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. The patent protection scope of the present utility model shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present utility model shall also be included within the protection scope of the present utility model.

Claims

1. An electric spindle, characterized in that, The device includes a housing and a rotating shaft. A front bearing housing is installed at the front end of the housing. The rotating shaft is rotatably mounted inside the housing via the front bearing installed in the front bearing housing. A clamping nut for clamping the front bearing is screwed onto the front end of the rotating shaft. A pressure cap is also connected to the front end of the housing and is positioned in front of the front bearing housing. The pressure cap has an inner hole through which the rotating shaft passes and into which the clamping nut extends. One of the clamping nut and the pressure cap has a spiral groove. The direction of the spiral groove is such that when the clamping nut rotates with the rotating shaft and rotates relative to the pressure cap, a forward-exhausting spiral exhaust structure is formed at the mating gap between the clamping nut and the pressure cap. The inner cavity of the housing communicates with the rear air intake side of the spiral groove. The housing has an air inlet that connects the inner cavity to the outside.

2. The electric spindle according to claim 1, characterized in that, The air passage between the air inlet and the rear air inlet side of the spiral groove includes an axial air passage disposed in the rotating shaft and a radial air passage at the front end of the axial air passage. The rear end of the axial air passage is connected to the air inlet, and the outer end of the radial air passage is connected to the inner cavity of the housing. The air passage also includes an axially penetrating bearing housing air passage disposed on the front bearing housing. The gas entering from the air inlet passes through the axial air passage, the radial air passage, the inner cavity of the housing, and the bearing housing air passage to the rear air inlet side of the spiral groove.

3. The electric spindle according to claim 2, characterized in that, The gland includes an annular cover and an axially extending convex ring located in the middle of the annular cover. The axially extending convex ring blocks the front side of the front bearing. The axially extending convex ring has a radially penetrating convex ring channel. The bearing housing air passage is connected to the rear air intake side of the spiral groove through the convex ring channel.

4. The electric spindle according to claim 2, characterized in that, The housing includes a cylindrical housing and a rear cover located at the rear end of the cylindrical housing. A rear bearing seat is provided at the rear end of the inner cavity of the cylindrical housing. The rear bearing seat is axially floatingly installed inside the cylindrical housing and is connected to a spring baffle at the rear end. A floating spring that provides preload force to the rear bearing is provided between the spring baffle and the cylindrical housing. An air guide pipe with both ends sealed and slidably inserted into the rear cover and the spring baffle is also provided between the rear cover and the spring baffle. The gas entering through the air inlet enters the axial air passage through the air guide pipe.

5. The electric spindle according to claim 1, characterized in that, An air filter is connected to the air inlet on the housing.

6. The electric spindle according to claim 5, characterized in that, The housing includes a cylindrical housing and a rear cover located at the rear end of the cylindrical housing, with an air inlet on the housing located on the rear cover.

7. The electric spindle according to claim 6, characterized in that, The air intake is located in the center of the rear cover, and a quick connector is also provided at the air intake. The quick connector connects to the air filter through the air intake pipe.

8. The electric spindle according to any one of claims 1-7, characterized in that, The compression nut has an outer flange that protrudes radially outward on the front side of the gland. The outer flange and the front side of the gland are fitted together by an annular convex and an annular groove to form a folded sealing structure.

9. The electric spindle according to claim 8, characterized in that, The front end of the housing is also connected to a dust cover. The front end of the rotating shaft passes through the middle of the dust cover. A gap for gas to be discharged is formed between the dust cover and the rotating shaft. The dust cover is fastened to the front end of the housing and covers the clamping nut and the pressure cap. The part of the inner side of the dust cover that is close to the clamping nut in the axial direction is the nut covering surface. The nut covering surface and the front end face of the clamping nut are connected by a ring protrusion and a ring groove to form a folded sealing structure.

10. The electric spindle according to claim 9, characterized in that, The inner side of the dust cover, which is close to the gland in the axial direction, is the gland cover shielding surface. The gland cover shielding surface is located behind the nut shielding surface, and there is an axial transition surface between the two. A drainage hole is also provided on the lower side of the dust cover at the location corresponding to the axial transition surface.

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