A main shaft rear end sealing structure, an electric spindle and a machine tool

Abstract

The application discloses a main shaft rear end sealing structure, an electric spindle and a machine tool, and relates to the technical field of machine tools. The main shaft rear end sealing structure comprises a machine body assembly, a shaft core which is rotatably installed on the machine body assembly and is internally provided with a central water hole, and a sealing structure which comprises a dynamic sealing cover. The dynamic sealing cover is installed on the shaft core and extends outward along the radial direction of the shaft core. The machine body assembly is provided with a sealing disc which extends along the radial direction of the shaft core. The dynamic sealing cover is arranged on the sealing disc from the direction close to the rear end of the shaft core. A labyrinth sealing structure is arranged between the dynamic sealing cover and the sealing disc. The machine body assembly is provided with an air inlet channel which is used for forming an air flow which is blown outward from the inside in the labyrinth sealing structure. According to the technical scheme of the application, multiple seals are arranged at the rear end of the main shaft, so that the electric spindle can continue to operate and process parts in the case of water leakage of the rotary joint and oil leakage of the oil cylinder, and the production efficiency is improved to a certain extent.

Description

Technical Field

[0001] This invention relates to the field of electric spindles, and in particular to a spindle rear end sealing structure, an electric spindle, and a machine tool. Background Technology

[0002] With the rapid development of the manufacturing industry, the electric spindle, as one of the core functional components of machine tools, has become increasingly sophisticated. This includes a center water outlet function, which is particularly important in high-speed, high-precision, deep-hole, and deep-cavity machining conditions. During the machining process, rinsing the parts with the center water outlet has the following benefits: 1. Controlling thermal deformation of parts and stabilizing dimensional accuracy; 2. Ensuring high-precision machining and improving the surface roughness of parts; 3. Reducing tool wear and extending tool life; 4. High-pressure forced chip removal, preventing chip blockage and tool breakage.

[0003] While electric spindles with center-outlet cooling play a crucial role in machining parts, they also present a significant hidden danger. If the electric spindle operates at high speed, high load, and with frequent tool changes for extended periods, over time, water leaks may occur at the rotary joint, a core component of the spindle, and oil leaks may occur from the hydraulic cylinder. If the rear end of the electric spindle is not properly sealed, the leaking cooling water and oil from the cylinder will flow into the bearings or motor, causing the electric spindle to burn out and requiring replacement, resulting in significantly increased repair costs.

[0004] In summary, the problems existing in the relevant technologies urgently need to be solved. Summary of the Invention

[0005] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a spindle rear end sealing structure, an electric spindle, and a machine tool.

[0006] The technical solution adopted by this invention to solve its technical problem is: In a first aspect, a rear end sealing structure for a spindle includes: Body components; A shaft core is rotatably mounted on the body assembly, and a central water hole is provided inside the shaft core; A sealing structure includes a dynamic sealing cover, which is mounted on the shaft core and extends radially outward along the shaft core. The body assembly has a sealing disc extending radially toward the shaft core. The dynamic sealing cover covers the sealing disc from a direction close to the rear end of the shaft core. A labyrinth sealing structure is provided between the dynamic sealing cover and the sealing disc. The body assembly has an air intake channel for forming an airflow blowing from the inside out in the labyrinth sealing structure.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, the sealing structure further includes an air seal sleeve, which is nested in the inner hole of the sealing disc. An annular groove is provided between the sealing disc and the air seal sleeve. An air seal gap is formed between the air seal sleeve and the inner shaft core or dynamic sealing cover. The air seal sleeve is provided with a plurality of air seal holes along the circumference that connect the annular groove and the air seal gap. The air inlet channel is provided with a first air passage that communicates with the annular groove.

[0008] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the gas seal sleeve extends axially rearward and protrudes from the sealing disc. The sealing structure further includes a static sealing ring disposed on the rear side of the sealing disc. The static sealing ring is axially floatingly fitted onto the gas seal sleeve. The sealing disc is provided with an elastic component for pushing the static sealing ring axially toward the dynamic sealing cover so that the dynamic sealing cover and the static sealing ring form a contact seal. The dynamic sealing cover has a plurality of air grooves on its bottom end face that mates with the static sealing ring. The plurality of air grooves are distributed circumferentially along the dynamic sealing cover. The dynamic sealing cover forms an air groove opening at the radial inner end of the air groove that communicates with the gas seal gap. The air groove extends from the air groove opening toward the root of the air groove in a direction away from the center of the dynamic sealing cover.

[0009] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the sealing disc is provided with an anti-rotation structure that guides the static sealing ring to float axially.

[0010] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the sealing disc and the static sealing ring are provided with a plurality of spring grooves along the axial direction, and the elastic component includes a compression spring disposed in the spring groove.

[0011] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the dynamic sealing cover is provided with a first convex ring and a second convex ring extending axially on the outer side of the static sealing ring, and an annular groove is formed between the first convex ring and the second convex ring. The sealing disc is provided with a third convex ring extending axially, and the third convex ring is embedded in the annular groove and has a clearance fit with the static sealing ring.

[0012] In combination with the first aspect and the above-mentioned implementation methods, in some implementation methods of the first aspect, a fitting gap is formed between the front end face of the static sealing ring and the sealing disc, and the air intake channel is provided with a second air passage connected to the fitting gap.

[0013] In combination with the first aspect and the above-described implementations, in some implementations of the first aspect, the body assembly is provided with an overflow hole at the root position of the sealing disc.

[0014] In a second aspect, an electric spindle includes the spindle rear end sealing structure described in any implementation of the first aspect.

[0015] Thirdly, a machine tool comprising an electric spindle as described in any implementation of the second aspect.

[0016] One of the above-mentioned technical solutions has at least one of the following advantages or beneficial effects: In the technical solution of the present invention, multiple seals are set at the rear end of the spindle. First, a dynamic seal cover is placed over the sealing disc from the direction close to the rear end of the shaft core, and a labyrinth seal structure is set at the axial overlap position to form the first layer of protection. This layer of protection can prevent a large amount of overflow water and overflow oil. At the same time, during operation, the air source can enter through the air intake channel and form an airflow from the inside to the outside along the labyrinth seal structure, forming a flowing gas barrier, thereby blocking the overflow water and overflow oil flowing through the first layer of protection, which is the second layer of protection. The technical solution of the present invention, by setting multiple seals at the rear end of the spindle, enables the electric spindle to continue operating and processing parts even when there is water leakage at the rotary joint and oil leakage in the hydraulic cylinder, thereby improving production efficiency to a certain extent.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of an embodiment of the present invention; Figure 2 This is a schematic diagram of the dynamic sealing cap structure according to an embodiment of the present invention; Figure 3 yes Figure 2 Cross-sectional view at point BB; Figure 4 yes Figure 1 Enlarged view of a portion of point A in the middle. Detailed Implementation

[0019] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0020] In this invention, when directions (up, down, left, right, front, and back) are described, it is only for the purpose of describing the technical solution of this invention, and does not indicate or imply that the technical features referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0021] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0022] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0023] in, Figure 1 The reference directions of the embodiments of the present invention are given below. Figure 1 The directions shown illustrate embodiments of the present invention.

[0024] See Figure 1 , Figure 4 An embodiment of the present invention provides a spindle rear end sealing structure, including a body assembly 100, a shaft core 200, and a sealing structure. The shaft core 200 serves as the power output shaft of the spindle and is rotatably mounted on the body assembly 100. A central water hole is provided inside the shaft core 200 to achieve a central water outlet function, for example... Figure 1 In the illustrated embodiment, a rotary joint 101 is provided at the rear end of the machine body assembly 100, and a rotating connecting rod 201 that mates with the rotary joint 101 is provided at the rear end of the shaft core 200. External cooling water can reach the front end of the shaft core 200 through the rotary joint 101, the rotating connecting rod 201, and the shaft core 200 to achieve cooling and chip removal of the tool or workpiece. A tool-removing cylinder 102 is also provided at the rear end of the machine body assembly 100. The tool-removing cylinder 102 is used to push the push rod assembly 202 inside the shaft core 200 axially to achieve an automatic tool release function, facilitating quick tool replacement.

[0025] During operation, due to the dynamic sealing structure inside the rotary joint 101, long-term high-speed rotation and water pressure fluctuations inevitably lead to a small amount of water leakage at the rotary joint 101 at the rear end of the spindle core 200. Simultaneously, the tool-changing cylinder 102, typically a hydraulic cylinder, will also experience slight oil seepage over time due to the reciprocating motion seal between its piston rod and cylinder body. If this leaked cooling water and hydraulic oil flows along the spindle core 200 towards the rear end and enters the bearing and motor areas, it will cause serious consequences such as bearing lubrication failure and motor insulation damage.

[0026] The sealing structure includes a dynamic sealing cover 301, which is mounted on the shaft core 200 and can rotate synchronously with the shaft core 200 during operation, and extends outward along the radial direction of the shaft core 200. The body assembly 100 is provided with a sealing disc 103 extending radially toward the shaft core 200. The dynamic sealing cover 301 covers the sealing disc 103 from the direction close to the rear end of the shaft core 200. A labyrinth sealing structure is provided between the dynamic sealing cover 301 and the sealing disc 103. The body assembly 100 is provided with an air intake channel 104, which is used to form an airflow blowing from the inside to the outside in the labyrinth sealing structure.

[0027] See Figure 1 , Figure 4 In the technical solution of the present invention, multiple seals are provided at the rear end of the main shaft to form layers of protection.

[0028] First, the dynamic seal cover 301 is installed on the sealing disc 103 from the direction near the rear end of the shaft core 200, and a labyrinth seal structure is set at the axial overlap position. This labyrinth seal structure increases the path length and flow resistance of external liquids penetrating into the spindle through tortuous fluid channels, forming the first line of protection. This line of protection can effectively block a large amount of leaked cooling water and hydraulic oil, preventing them from directly entering the spindle.

[0029] Meanwhile, during operation, an external air source introduces compressed gas through the air intake channel 104. The gas forms an airflow blowing outwards along the labyrinth seal structure. This airflow forms a dynamic gas barrier in the labyrinth gaps, its direction opposite to the direction of liquid seepage, thus blowing away any residual overflow water and oil that has passed through the first layer of protection, preventing them from further penetrating into the spindle. This is the second layer of protection, namely the air curtain seal.

[0030] This invention employs a multi-layered protection system—a labyrinth seal and an air curtain seal—at the rear end of the spindle. This ensures that even if the rotary joint 101 leaks water or the tool holder cylinder 102 leaks oil, the electric spindle can continue to operate normally and process parts without immediate shutdown due to liquid seepage. This significantly improves the spindle's fault tolerance and production continuity, thereby increasing production efficiency to some extent and reducing unplanned downtime caused by accidental water or oil leaks.

[0031] In some embodiments, see Figure 1 , Figure 2 The sealing structure also includes an air seal sleeve 302, which is nested in the inner hole of the sealing disc 103. An annular groove 303 is provided between the sealing disc 103 and the air seal sleeve 302. An air seal gap 304 is formed between the air seal sleeve 302 and the inner shaft core 200 or the dynamic sealing cover 301. The air seal sleeve 302 is provided with a plurality of air seal holes along the circumference that connect the annular groove 303 and the air seal gap. The air inlet channel 104 is provided with a first air passage 105 that communicates with the annular groove 303. During operation, compressed gas enters the annular groove 303 between the sealing disc 103 and the gas sealing sleeve 302 through the first gas passage 105. The gas circulates once within the annular groove 303, achieving pressure equalization. Then, it passes through multiple circumferentially distributed gas sealing holes on the gas sealing sleeve 302, evenly reaching the gas sealing gap 304 between the gas sealing sleeve 302 and the inner shaft core 200 or the dynamic sealing cover 301. Finally, it enters the labyrinth seal structure between the dynamic sealing cover 301 and the sealing disc 103, forming a uniform and stable gas flow barrier. By setting the gas sealing sleeve 302 and evenly distributing the gas sealing holes on it, the airflow entering the labyrinth seal is evenly distributed in the circumferential direction, avoiding the sealing effect affected by insufficient or excessive local airflow, thus ensuring the reliability and stability of the air curtain seal.

[0032] Furthermore, in some embodiments, see Figure 1 , Figure 2 , Figure 3 , Figure 4 The air seal sleeve 302 extends axially rearward and protrudes from the sealing disc 103 to form an axially extending guide sleeve for setting the static sealing ring 305. The sealing structure also includes a static sealing ring 305 disposed on the rear side of the sealing disc 103. The static sealing ring 305 can be axially floatingly fitted onto the air seal sleeve 302. The sealing disc 103 is provided with an elastic member 306 for pushing the static sealing ring 305 axially toward the dynamic sealing cover 301 so that the dynamic sealing cover 301 and the static sealing ring 305 form a contact seal. The dynamic sealing cover 301 has a plurality of air grooves 307 on the bottom end face that mates with the static sealing ring 305. The plurality of air grooves 307 are distributed circumferentially along the dynamic sealing cover 301. The dynamic sealing cover 301 forms an air groove opening 308 at the radial inner end of the air groove 307 that communicates with the air seal gap. The air groove 307 extends from the air groove opening 308 toward the dynamic sealing cover 301 in a direction away from the center to the air groove root 309.

[0033] See Figure 1 , Figure 4 In the technical solution of the present invention, a third seal is further provided—a dynamic and static ring contact seal.

[0034] When the spindle is stopped and the spindle core 200 is not rotating, the static sealing ring 305, under the axial thrust of the elastic component 306, tightly fits against the mating end face of the dynamic sealing cover 301, forming a contact seal. This contact seal completely blocks the path of impurities (including overflow water, overflow oil, and small particles such as external dust and chips) into the spindle, effectively preventing small impurities from entering the spindle through the mating gap between the dynamic sealing cover 301 and the sealing disc 103, thus achieving absolute sealing when the spindle is stopped.

[0035] When the spindle is operating normally, the spindle core 200 begins to rotate at high speed. At this time, compressed gas flows in through the first air passage 105 and enters the air groove 307 through the air groove opening 308 of the dynamic seal cover 301. Since the air groove 307 rotates synchronously with the dynamic seal cover 301, under the combined action of centrifugal force and hydrodynamic pressure effect, the gas in the air groove 307 is pumped away from the center of the dynamic seal cover 301 (i.e., the root 309 of the air groove), and the gas pressure rises significantly at the root 309 of the air groove, generating hydrodynamic pressure. This hydrodynamic pressure acts on the end face of the static seal ring 305, forming a thrust that overcomes the axial force of the elastic component 306. When the elastic force of the elastic component 306 and the hydrodynamic pressure reach equilibrium, a very small gap (micrometer level) will be formed between the static seal ring 305 and the dynamic seal cover 301. Within this tiny gap, the high-speed flowing gas forms a stable gas film. This gas film serves both as a seal (effectively preventing tiny impurities from entering) and as a means to prevent direct solid contact between the static sealing ring 305 and the dynamic sealing cover 301, thereby reducing friction, wear, and heat generation.

[0036] This embodiment, based on labyrinth seals and air curtain seals, further achieves effective sealing of the spindle under both static and rotating conditions through a contact / non-contact composite sealing design between the static sealing ring 305 and the dynamic sealing cover 301. This multi-stage combined sealing structure significantly improves the spindle's sealing capability, resulting in better sealing reliability and effect, and can meet the extremely stringent requirements of high-speed machining centers, precision machine tools, and other equipment with stringent requirements for spindle precision and protection.

[0037] In some embodiments, the sealing disc 103 is provided with an anti-rotation structure to guide the static sealing ring 305 to float axially. The anti-rotation structure may be a guide pin, guide groove, or guide key extending axially. The anti-rotation structure cooperates with the static sealing ring 305 to ensure that the static sealing ring 305 only has the freedom to float axially and cannot rotate with the moving sealing cover 301.

[0038] The elastic component 306 may be a leaf spring, disc spring, or spring, etc. See in some embodiments. Figure 4The sealing disc 103 and the static sealing ring 305 are provided with multiple spring grooves along the axial direction, and the elastic component 306 includes compression springs disposed in the spring grooves. Multiple compression springs are arranged circumferentially to provide a balanced axial force to the static sealing ring 305, ensuring that the shaft core 200 can form a reliable seal with the dynamic sealing cover 301 when it is not rotating.

[0039] In some embodiments, the extension direction of the air groove 307 from the air groove opening 308 to the air groove root 309 is opposite to the rotation direction of the shaft core 200, and the groove width of the air groove 307 narrows along the direction from the air groove opening 308 to the air groove root 309. This spiral or tapering air groove 307 design can more effectively capture gas and generate a compression pumping effect when the shaft core 200 rotates, causing the gas to flow from the opening end to the root and be compressed, forming a higher pressure accumulation at the root, thereby more effectively overcoming the elastic force of the elastic member 306 to push the static sealing ring 305 open, and forming a more stable high-pressure gas film at the air groove root 309, further improving the dynamic pressure sealing effect.

[0040] In some embodiments, see Figure 4 The front end face of the static sealing ring 305 forms a fitting gap with the sealing disc 103, and the air intake channel 104 is provided with a second air passage 106 that connects to the fitting gap.

[0041] See Figure 3 , Figure 4 The dynamic sealing cover 301 has a first convex ring 310 and a second convex ring 311 extending axially on the outside of the static sealing ring 305. An annular groove is formed between the first convex ring 310 and the second convex ring 311. The sealing disc 103 has a third convex ring 312 extending axially. The third convex ring 312 is embedded in the annular groove and has a clearance fit with the static sealing ring 305.

[0042] During operation, the air source enters through the air intake channel 104, and part of the airflow enters the second air passage 106. It flows through the mating gap between the front end face of the static sealing ring 305 and the sealing disc 103, and then enters the labyrinth seal structure composed of the first convex ring 310, the third convex ring 312, and the second convex ring 311, forming another layer of air curtain seal. By setting up the second air passage 106, independent of the first air passage 105, it is possible to ensure that when the static sealing ring 305 and the dynamic sealing cover 301 are in a contact sealing state (e.g., when the spindle is just started or at low speed, the dynamic pressure is insufficient to push open the static sealing ring 305), even if the first air passage 105 has no airflow for any reason, a continuous air curtain seal can still be formed in the labyrinth seal structure through the second air passage 106, thus achieving uninterrupted protection under all operating conditions. After the shaft core 200 rotates, another portion of the airflow enters the first air passage 105 and, following the aforementioned path, ultimately forms a dynamic pressure air film at the root 309 of the air groove, creating a non-contact, minute gap between the static sealing ring 305 and the dynamic sealing cover 301. This dual air passage design complements and redundant the air curtain seal and the static / dynamic ring seal, significantly improving the fault tolerance and overall reliability of the sealing system.

[0043] In some embodiments, see Figure 1 The body assembly 100 has an overflow hole 107 at the root of the sealing disc 103. Overflow water and oil are blown through the air curtain to the overflow hole 107 in the sealing disc 103, and then flow through the overflow hole 107 in the body assembly 100, finally draining out to the outside of the front end of the body assembly 100. By providing the overflow hole 107, a clear discharge path is provided for the liquid intercepted by the air curtain, preventing liquid accumulation at the sealing disc 103, thus avoiding liquid seepage into the spindle along the gaps and ensuring the long-term effectiveness of the sealing structure.

[0044] This invention, by employing the aforementioned multi-stage sealing structure, fundamentally eliminates the long-standing industry problem of damage to the electric spindle bearings and motor caused by water leakage from the rotary joint 101 and oil leakage from the tool-changing cylinder 102. In the past, if an electric spindle experienced water or oil leakage during parts processing, the bearings and motor would quickly fail, causing the spindle to stop operating and the processed parts to be scrapped. However, this invention, by setting a double air curtain seal and a composite seal structure of dynamic and static rings at the rear end of the spindle, significantly improves the electric spindle's resistance to water and oil leakage. Even if the seals show some wear or aging, they can still effectively prevent liquid from seeping into the spindle before replacement, ensuring the spindle can continue normal processing. This significantly improves the product's pass rate, greatly reduces maintenance costs and downtime losses due to spindle damage, and significantly extends the overall service life of the electric spindle.

[0045] Embodiments of the present invention also provide an electric spindle, including the spindle rear end sealing structure of any of the above embodiments.

[0046] Embodiments of the present invention also provide a machine tool including the electric spindle of any of the above embodiments.

[0047] In the description of this specification, references to terms such as "example," "embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] Of course, the present invention is not limited to the above-described embodiments. Those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A sealing structure for the rear end of a spindle, characterized in that, include: Body components; A shaft core is rotatably mounted on the body assembly, and a central water hole is provided inside the shaft core; A sealing structure includes a dynamic sealing cover, which is mounted on the shaft core and extends radially outward along the shaft core. The body assembly has a sealing disc extending radially toward the shaft core. The dynamic sealing cover covers the sealing disc from a direction close to the rear end of the shaft core. A labyrinth sealing structure is provided between the dynamic sealing cover and the sealing disc. The body assembly has an air intake channel for forming an airflow blowing from the inside out in the labyrinth sealing structure.

2. The spindle rear end sealing structure according to claim 1, characterized in that, The sealing structure further includes an air seal sleeve, which is nested in the inner hole of the sealing disc. An annular groove is provided between the sealing disc and the air seal sleeve. An air seal gap is formed between the air seal sleeve and the inner shaft core or dynamic sealing cover. The air seal sleeve is provided with a plurality of air seal holes along the circumference that connect the annular groove and the air seal gap. The air inlet channel is provided with a first air passage that communicates with the annular groove.

3. The spindle rear end sealing structure according to claim 2, characterized in that, The gas seal sleeve extends axially rearward and protrudes from the sealing disc. The sealing structure also includes a static sealing ring disposed on the rear side of the sealing disc. The static sealing ring is axially floatingly fitted onto the gas seal sleeve. The sealing disc is provided with an elastic component for pushing the static sealing ring axially toward the dynamic sealing cover so that the dynamic sealing cover and the static sealing ring form a contact seal. The dynamic sealing cover has a plurality of air grooves on its bottom end face that mates with the static sealing ring. The plurality of air grooves are distributed circumferentially along the dynamic sealing cover. The dynamic sealing cover forms an air groove opening at the radial inner end of the air groove that communicates with the gas seal gap. The air groove extends from the air groove opening toward the root of the air groove in a direction away from the center of the dynamic sealing cover.

4. The spindle rear end sealing structure according to claim 3, characterized in that, The sealing disc is equipped with an anti-rotation structure that guides the static sealing ring to float axially.

5. The spindle rear end sealing structure according to claim 3, characterized in that, The sealing disc and the static sealing ring are provided with a plurality of spring grooves along the axial direction, and the elastic component includes a compression spring disposed in the spring groove.

6. The spindle rear end sealing structure according to claim 3, characterized in that, The dynamic sealing cover has a first convex ring and a second convex ring extending axially on the outside of the static sealing ring, and an annular groove is formed between the first convex ring and the second convex ring. The sealing disc has a third convex ring extending axially, which is embedded in the annular groove and has a clearance fit with the static sealing ring.

7. The spindle rear end sealing structure according to claim 6, characterized in that, The front end face of the static sealing ring forms a fitting gap with the sealing disc, and the air intake channel is provided with a second air passage that connects to the fitting gap.

8. The spindle rear end sealing structure according to claim 1, characterized in that, The body assembly has an overflow hole at the root of the sealing disc.

9. An electric spindle, characterized in that, Includes the spindle rear end sealing structure as described in any one of claims 1 to 8.

10. A machine tool, characterized in that, Includes the electric spindle as described in claim 9.

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