Air seal structure for a main shaft and method for assembling the same

Abstract

The application provides a gas seal structure for a main shaft, comprising a shaft core, a shell and a gas seal nut assembly; the shaft core comprises a first part inserted into the shell and a second part forming a labyrinth seal with the shell; the second part is provided with a first boss forming a labyrinth seal with the shell on a side thereof facing the shell; the shell is provided with a first groove for forming a labyrinth seal with the first boss of the shaft core; the gas seal nut assembly comprises a locking nut and a sealing sleeve; the locking nut is outwardly convex on an upper part thereof to form a threaded outer edge connected with the shell; the locking nut has a cavity for embedding the sealing sleeve, an inner wall of the cavity extends inwardly along a radial direction to form a first step matched with the sealing sleeve, and a second groove is arranged on a side of the first step facing inwardly; the second part of the shaft core is further provided with a second boss forming a labyrinth seal with the second groove on a side thereof facing the shell. The structure can realize labyrinth seal, air curtain seal and pressurized bearing. The application further provides an assembling method of the gas seal structure.

Description

Technical Field

[0001] This invention relates to the field of spindle air seal structure technology and equipment, and in particular to an air seal structure for a spindle and its assembly method. Background Technology

[0002] A mechanical spindle refers to the shaft on a machine tool that drives the workpiece to rotate. It typically consists of a spindle, bearings, and transmission components. In a machine, it primarily supports transmission parts such as gears and pulleys, transmitting motion and torque. An electric spindle, on the other hand, is a new technology that emerged in the field of CNC machine tools, integrating the machine tool spindle and spindle motor into one unit. The spindle includes the electric spindle itself and its accessories. This transmission structure, where the spindle motor and machine tool spindle are "integrated," makes the spindle component relatively independent from the machine tool's transmission system and overall structure.

[0003] The air seal structure plays a crucial role in ensuring the long lifespan, stability, and high efficiency of mechanical or electric spindles. Currently, most mechanical and electric spindles on the market use an air seal structure typically designed on the front pressure cover. If this design fails, cutting fluid, oil mist, and dust from the machining process will enter the bearing, leading to lubrication failure and, in more severe cases, seizure. Furthermore, the front pressure cover requires precise tolerance matching with the bearing, spacer, and housing; otherwise, it cannot ensure proper pressure on the bearing outer ring. This design introduces several drawbacks: Firstly, the current spindle air seal structure, typically located on the front pressure cover, requires screw connections to the housing, inevitably reducing the number of labyrinth seals between the spindle and the front pressure cover. This results in poor bearing preload, limited protection, and mediocre waterproofing and dustproofing. Secondly, there is a risk of spindle movement, which can accelerate bearing damage and compromise the precision of parts manufactured in subsequent processes. When the production process is not precisely controlled, the entire spindle is highly susceptible to damage, and both the spindle and its bearings are extremely expensive. This not only complicates the production process but also significantly increases maintenance costs. Summary of the Invention

[0004] The main technical problem to be solved by the present invention is to provide an air seal structure for a spindle, which can improve the protection performance of the spindle and achieve the excellent effect of effective spindle sealing and reliable bearing preload.

[0005] The main technical problem to be solved by the present invention is to provide an assembly method for the gas seal structure as described above. This assembly method can preload the bearing into place, simplify the assembly steps of the gas seal structure, and improve the assembly efficiency of the gas seal structure.

[0006] To address the aforementioned technical problems, the present invention provides an air-sealing structure for a spindle, comprising: a spindle core, a housing, and an air-sealing nut assembly; the spindle core includes: a first portion inserted into the housing and a second portion forming a labyrinth seal with the front end of the housing; the second portion has a first boss on its side facing the housing, which engages with the housing to form a labyrinth seal; the front end of the housing has a first groove for forming a labyrinth seal with the first boss of the spindle core; the air-sealing nut assembly includes a locking nut and a sealing sleeve; the upper portion of the locking nut protrudes radially outward to form a threaded outer edge that connects to the housing; the locking nut has a chamber for fitting the sealing sleeve, the inner wall of the chamber extending radially inward to form a first step that engages with the sealing sleeve, and a second groove on the radially inward side of the first step; the second portion of the spindle also has a second boss on its side facing the housing, which forms a labyrinth seal with the second groove.

[0007] In a preferred embodiment: the second part of the shaft core is further provided with a boss outer end on the side facing the housing for cooperating with the end of the front outer wall of the housing to form a labyrinth seal; the shaft core is provided with a second step at the connection between the first part and the second part, the second step being used to fit the inner ring of the bearing.

[0008] In a preferred embodiment, a connecting portion is further provided between the first boss and the second boss, the connecting portion being used to cooperate with the inner side of the front end of the housing and the air seal nut assembly to form a labyrinth seal and an air curtain seal.

[0009] In a preferred embodiment: the outer side of the second part of the labyrinth seal formed by the shaft core and the front end of the housing is provided with a first oblique groove that is radially inwardly recessed for guiding the cutting fluid.

[0010] In a preferred embodiment: the inner side of the front end of the housing is provided with threads, which are connected to the outer edge of the air seal nut assembly by screwing; the outer wall of the front end of the housing is provided with a second inclined groove for guiding the cutting fluid and a through hole for air to be introduced into the housing to form an air curtain seal with the air seal nut assembly and the shaft core.

[0011] In a preferred embodiment: the sealing sleeve includes: an upper end face and a lower end face; an outer circle formed by the radially outward extension of the upper end face, the outer circle of the upper end face and the lower end face are fitted with a first step provided in the locking nut cavity for conducting air passage; the upper end face of the sealing sleeve is evenly distributed with circular holes for air outlet to form an air curtain seal with the shaft core and the housing.

[0012] In a preferred embodiment: the lower part of the outer wall of the locking nut is provided with a vent hole, which is used to guide the gas introduced into the housing into the sealing sleeve.

[0013] In a preferred embodiment: the air seal structure further includes a bearing; the locking nut of the air seal nut assembly presses against the outer ring of the bearing, and after pressing against the outer ring of the bearing, the end face of the air seal nut assembly is higher than the end face of the housing.

[0014] In a preferred embodiment: a first process hole for engaging with a locking fixture is further provided at the position of the second groove of the locking nut.

[0015] To solve the above-mentioned technical problems, the present invention also provides an assembly method for the air seal structure as described above: assembly is performed using a locking fixture; the outer wall surface of the locking fixture away from the center is provided with a radially inwardly recessed groove for engaging a hook-shaped torque wrench; the locking fixture further includes a second process hole, which is located on the inner side of the locking fixture and is used to insert a pin to engage with the first process hole of the locking nut of the air seal nut assembly to press the bearing.

[0016] The assembly method includes the following steps:

[0017] (1) Fix the housing on the three-jaw chuck, and then install the spacer assembly and bearing into the inner cavity of the housing in sequence;

[0018] (2) Align the first process hole of the locking nut with the second process hole of the locking fixture, and insert a pin into the process hole as described above. Then, use the locking fixture to lock the air seal nut assembly to the outer ring of the bearing through the cooperation of the groove and the hook wrench. After the locking task is completed, remove the locking fixture.

[0019] (3) The shaft core is cold-pressed into the housing, the air seal nut assembly, the bearing and the spacer assembly until the second step of the shaft core is in contact with the inner ring of the bearing.

[0020] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0021] 1. This invention provides an air seal structure for a spindle, which integrates multiple functions such as labyrinth seal, air curtain seal and bearing clamping through the mutual cooperation between the air seal nut assembly and the steps, bosses and grooves of the spindle core, housing and internal structure, greatly improving the protection performance.

[0022] 2. This invention provides an air seal structure for a spindle. The air seal nut assembly and the housing are screwed together, which ensures that the outer ring of the bearing inside the housing can be effectively pre-tightened to prevent the spindle from moving. Furthermore, by controlling the tolerances, the end face of the air seal nut assembly is higher than the end face of the housing, which effectively prevents liquid dust from flowing into the bearing and avoids wear on bearings and other components. Compared with traditional structures, this design is simpler, more compact, easier to install, and can save material and labor costs.

[0023] 3. The present invention also provides an assembly method for an air seal structure for a spindle, which uses a locking fixture to assist in assembly. By inserting a pin into the process hole of the air seal nut assembly, and utilizing the cooperation between the hook wrench and the groove of the locking fixture, the bearing can be pre-tightened in place, simplifying the assembly steps of the air seal structure and improving the assembly efficiency of the air seal structure. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the sealing principle of the gas seal structure in the preferred embodiment 1 of the present invention;

[0025] Figure 2 This is a cross-sectional view of the shaft core in preferred embodiment 1 of the present invention;

[0026] Figure 3 This is a cross-sectional view of the shell in preferred embodiment 1 of the present invention;

[0027] Figure 4 This is a cross-sectional view of the gas-sealed nut assembly in preferred embodiment 1 of the present invention;

[0028] Figure 5 This is a cross-sectional view of the locking nut in preferred embodiment 1 of the present invention;

[0029] Figure 6 This is a top view of the locking nut in the preferred embodiment 1 of the present invention;

[0030] Figure 7 This is a cross-sectional view of the sealing sleeve in preferred embodiment 1 of the present invention;

[0031] Figure 8 for Figure 1 A magnified view of a section at point A in the middle;

[0032] Figure 9 This is a top view of the locking fixture in preferred embodiment 2 of the present invention;

[0033] Figure 10 This is a schematic diagram of the installation of the gas seal nut assembly in preferred embodiment 2 of the present invention;

[0034] Figure 11 This is a schematic diagram of the cold-pressed shaft core in preferred embodiment 2 of the present invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0038] Example 1

[0039] refer to Figures 1-8 This embodiment provides an air seal structure for a spindle, including: a spindle core 1, a housing 2, and an air seal nut assembly 3; the spindle core 1 includes: a first part 11 inserted into the housing 2 and a second part 12 forming a labyrinth seal with the front end of the housing 2; the second part 12 has a first boss 122 on the side facing the housing 2 for forming a labyrinth seal with the housing 2; the front end of the housing 2 has a first groove 21 for forming a labyrinth seal with the first boss 122 of the spindle core 1; the air seal nut assembly 3 includes a locking nut 31 and a sealing sleeve 32; the locking nut 31... The upper part 311 of the nut 31 protrudes radially outward to form a threaded outer edge 3111 that connects to the housing 2; the locking nut 31 has a chamber 313 for fitting the sealing sleeve 32, and the inner wall of the chamber 313 extends radially inward to form a first step 3131 that mates with the sealing sleeve 32. A second groove 3132 is provided on one side of the first step 3131 that extends radially inward; the second part 12 of the shaft core 1 also has a second boss 124 on the side facing the housing 2 that forms a labyrinth seal with the second groove 3132.

[0040] More specifically, the shaft core 1 includes: a first part 11 inserted into the housing 2 and a second part 12 forming a labyrinth seal with the front end of the housing 2; the second part 12 has two first protrusions 122 on the side facing the housing 2, which can combine with the first groove 21 of the housing 2 to form a labyrinth seal. In this embodiment, the number of first protrusions 122 on the side of the second part 12 facing the housing 2 is at least one, and in this embodiment, the number of first protrusions 122 is specifically described as two. The second part 12 of the shaft core 1 also has a second protrusion 124 on the side facing the housing 2, which forms a labyrinth seal with the gas-sealing nut assembly 3. Specifically, the second protrusion 124 forms a labyrinth seal with the second groove 3132 of the locking nut 31 of the gas-sealing nut assembly 3.

[0041] Furthermore, the second part 12 of the shaft core 1 has a boss outer end 121 on the edge facing the housing 2, which is used to cooperate with the end of the front outer wall of the housing 2 to form a labyrinth seal. A connecting part 123 is also provided between the first boss 122 and the second boss 124. The connecting part 123 is used to cooperate with the inner side of the front end of the housing 2 and the air seal nut assembly 3 to form a labyrinth seal and an air curtain seal. The outer wall of the second part 12 of the shaft core 1 has a first oblique groove 125. The first oblique groove 125 forms a recess radially inward to guide the cutting fluid, which can effectively guide the cutting fluid to the oblique groove and prevent the liquid from entering the machine body. The shaft core 1 has a second step 13 at the connection between the first part 11 and the second part 12. The second step 13 is used to press the bearing inner ring 42 of the bearing 4.

[0042] Furthermore, the front end of the housing 2 is provided with a first groove 21 for forming a labyrinth seal with the first boss 122 of the shaft core 1. The first groove 21 and the first boss 122 are compatible. Therefore, it can be understood that in this embodiment, the number of first bosses 122 and first grooves 21 that can form a labyrinth seal is not limited to the two shown in the figures. The number of first bosses 122 and first grooves 21 that cooperate to form a labyrinth seal is at least one, and the specific number can be designed according to actual usage requirements, and can also be three, four, five, or six. A first thread 24 with a specification of M63×1 and a depth of 13 is provided on the inner wall of the front end of the housing 2 near the outer edge 3111 of the gas seal nut assembly 3, which is screwed to the outer edge 3111 of the locking nut 31 of the gas seal nut assembly 3. The outer wall of the front end of the housing 2 is provided with a second oblique groove 22 and a through hole 23. The second oblique groove 22 can effectively guide the cutting fluid to the oblique groove, preventing liquid from entering the machine body. The through hole 23 has a diameter of 4mm, and a G1 / 8 threaded hole is provided above the through hole 23 for connecting an air connector. Here, the through hole 23 of the housing 2 can be connected to the air connector to allow air to enter the housing 2, and an air curtain seal is formed by the cooperation of the connecting part 123 of the shaft core 1, the inner side of the front end of the housing 2, and the air seal nut assembly 3.

[0043] The air seal nut assembly 3 is composed of a locking nut 31 and a sealing sleeve 32, which are heat-fitted and press-fitted with adhesive. The air seal nut assembly 3, the shaft core 1, and the housing 2 work together to form a labyrinth seal and an air curtain seal. Through multiple layers of protection, it effectively prevents liquids and dust from entering the machine body, thereby protecting internal parts such as the bearing 4 and improving product life.

[0044] Specifically, in this embodiment, the locking nut 31 of the gas-sealing nut assembly 3 further includes an upper part 311, a lower part 312, and a chamber 313. The upper part 311 of the locking nut 31 protrudes radially outward to form a threaded outer edge 3111 that connects to the inner side of the front end of the housing 2. The chamber 313 of the locking nut 31 is used to fit the sealing sleeve 32. The inner wall of the chamber 313 extends radially inward to form a first step 3131 that mates with the sealing sleeve 32. A second groove 3132 is provided on one side of the first step 3131 that mates radially inward. It is worth noting that the second groove 3132 mates with the second boss 124 of the shaft core 1 to form a labyrinth seal. The lower part 312 of the locking nut 31 is provided with a vent hole 3121 with a diameter of 2mm. The vent hole 3121 is used to guide the gas input from the through hole 23 of the housing 2 into the sealing sleeve 32 of the air-sealing nut assembly 3. The gas then enters the machine body through the vent hole 3121. At the connection part 123 of the shaft core 1, an air curtain seal is formed by the cooperation of the connection part 123 of the shaft core 1, the inner side of the front end of the housing 2, and the air-sealing nut assembly 3. At the position of the second groove 3132 of the locking nut 31, there are also two first process holes 3133 with a diameter of 3mm for cooperating with the locking fixture 5. The first process holes 3133 do not penetrate the air-sealing nut assembly 3.

[0045] In detail, the sealing sleeve 32 includes an upper end face 321 and a lower end face 322. The upper end face 321 extends radially outward to form an outer circle 3212. The outer circle 3212 of the upper end face 321 of the sealing sleeve 32 connects to the inner wall of the upper part 311 of the locking nut 31, and the lower end face 322 fits against the first step 3131 provided in the cavity 313 of the locking nut 31, which is used to conduct air passage and provide strong support for forming an air curtain seal. The upper end face 321 of the sealing sleeve 32 has 24 evenly distributed circular holes 3211 with a diameter of 1 mm. The circular holes 3211 are used for air outlet, which cooperate with the connecting part 123 of the shaft core 1, the inner side of the front end of the housing 2, and the air seal nut assembly 3 to form an air curtain seal.

[0046] The air seal structure also includes a bearing 4. By controlling the tolerances, the locking nut 31 of the air seal nut assembly 3 presses against the outer ring 41 of the bearing 4, and after pressing against the outer ring 41 of the bearing 4, the end face of the air seal nut assembly 3 is 0.2mm higher than the end face of the housing 2. This prevents the shaft core 1 from shifting, and the height difference of the end faces effectively prevents liquid and dust from entering the machine body. Specifically, in this embodiment, it can be understood that after the locking nut 31 of the air seal nut assembly 3 presses against the outer ring 41 of the bearing 4, the end face of the air seal nut assembly 3 near the shaft core 1 connecting part 123 is higher than the end face of the inner front end of the housing 2 near the shaft core 1 connecting part 123, and the height difference is 0.2mm.

[0047] Example 2

[0048] refer to Figures 9-11 This embodiment provides an assembly method for the air seal structure as described above: assembly is performed using a locking fixture 5; the outer wall surface of the locking fixture 5 away from the center is provided with a radially inward recessed groove 51 for engaging a hook-shaped torque wrench; the locking fixture 5 also includes a second process hole 52, which is provided on the locking fixture 5 for inserting a pin 6 to engage with the first process hole 3133 of the locking nut 31 of the air seal nut assembly 3 to press the bearing 4.

[0049] More specifically, in this embodiment, installing the gas-sealed nut assembly 3 as described above requires a locking fixture 5. The locking fixture 5 includes a groove 51, a second process hole 52, and a first end for abutting the gas-sealed nut assembly 3. From a top view, the locking fixture 5 is approximately circular in shape; for better description, in this embodiment, its center position from a top view is referred to as the center. The groove 51 is located on the outer wall surface away from the center of the locking fixture 5 and is radially recessed inwards. The groove 51 is used to engage with a hook-shaped torque wrench to operate the locking fixture 5. Specifically, the number of grooves 51 on the outer wall surface of the locking fixture 5 is at least one; in this embodiment, the number of grooves 51 on the outer wall surface of the locking fixture 5 is three, and the three grooves 51 have the same recessed shape and are evenly spaced.

[0050] The second process hole 52 is located near the center of the locking fixture 5. In this embodiment, there are two second process holes 52 on the locking fixture 5, which are relatively distributed and each has a diameter of 3mm. The second process hole 52 penetrates the locking fixture 5. The second process hole 52 can be used to insert the pin 6, which engages with the first process hole 3133 of the locking nut 31 of the air seal nut assembly 3 to press the bearing 4. As a simple alternative in this embodiment, the number of second process holes 52 on the locking fixture 5 is at least one; this embodiment uses two as an example. It should be noted that in this embodiment, the number of second process holes 52 on the locking fixture 5 is equal to the number of first process holes 3133 on the locking nut 31, and the first process holes 3133 and the second process holes 52 are corresponding. It can be understood that understanding the structure of the locking fixture 5 helps us quickly assemble the air seal nut assembly 3. The assembly method in this embodiment includes the following steps:

[0051] (1) First, fix the rear end of the housing 2 onto the three-jaw chuck, and then install the spacer assembly 7 and the bearing 4 into the inner cavity of the housing in sequence.

[0052] (2) Next, the lower part 312 of the locking nut 31 of the air seal nut assembly 3 is oriented toward the bearing 4 and inserted into the inner cavity of the housing 2 to initially abut against the outer ring 41 of the bearing 4. Then, the locking fixture 5 is clamped in the inner cavity of the housing 2 and squeezes the air seal nut assembly 3.

[0053] (3) At this time, it is necessary to align the first process hole 3133 of the locking nut 31 and the second process hole 52 of the locking fixture 5, and insert the prepared pin 6 into the process hole as described above. The hole diameter and length of the pin 6 are adapted to the process hole as described above. Then, the hook end of the hook torque wrench is locked on the groove 51 of the locking fixture 5. Then, the handle end of the hook torque wrench is rotated by the external force to turn the locking fixture 5. Under the influence of the increasing external force, the air seal nut assembly 3 and the bearing outer ring 41 of the bearing 4 are gradually locked. When the locking fixture 5 stops operating and the torque wrench shows that the set pre-tightening torque has been reached, the air seal nut assembly 3 and the bearing outer ring 41 of the bearing 4 are completely locked. After the locking task is completed, the locking fixture 5 and the pin 6 are removed.

[0054] (4) The shaft core 1 is cold-pressed into the housing 2 and passed through the air seal nut assembly 3, bearing 4 and spacer assembly 7 in sequence until the second step 13 of the shaft is tightly fitted with the inner ring 42 of the bearing 4.

[0055] After completing the above steps, at this time, the end face of the air seal nut assembly 3 near the connecting part 123 of the shaft core 1 is higher than the end face of the inner side of the front end of the housing 2 near the connecting part 123 of the shaft core 1, and the height difference is 0.2mm.

[0056] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. An air seal structure for a spindle, characterized in that, include: Shaft core, housing, and gas seal nut assembly; The shaft core includes: a first part that is inserted into the housing and a second part that forms a labyrinth seal with the front end of the housing; The second part has a first boss on the side facing the housing to form a labyrinth seal with the housing; the front end of the housing has a first groove for forming a labyrinth seal with the first boss of the shaft core; the gas seal nut assembly includes a locking nut and a sealing sleeve; the upper part of the locking nut protrudes radially outward to form a threaded outer edge that connects to the housing; the locking nut has a chamber for fitting the sealing sleeve, the inner wall of the chamber extends radially inward to form a first step that mates with the sealing sleeve, and a second groove is provided on the radially inward side of the first step; the second part of the shaft core also has a groove on the side facing the housing that mates with the second groove. The groove forms a second boss for the labyrinth seal; the second part of the shaft core is also provided with an outer end of the boss facing the housing, which is used to cooperate with the outer wall end of the front end of the housing to form a labyrinth seal; the shaft core is provided with a second step at the connection between the first part and the second part, which is used to fit the inner ring of the bearing; a connecting part is also provided between the first boss and the second boss, which is used to cooperate with the inner side of the front end of the housing and the gas seal nut assembly to form a labyrinth seal and an air curtain seal; the gas seal structure also includes a bearing; the locking nut of the gas seal nut assembly presses the outer ring of the bearing, and after pressing the outer ring of the bearing, the end face of the gas seal nut assembly is higher than the end face of the housing.

2. The air seal structure for a spindle according to claim 1, characterized in that: The outer side of the second part of the shaft core and the front end of the housing forming a labyrinth seal is provided with a first oblique groove that is radially inwardly recessed for guiding the cutting fluid.

3. The air seal structure for a spindle according to claim 1, characterized in that: The inner side of the front end of the housing is provided with threads, which are connected to the outer edge of the air seal nut assembly by screwing. The outer wall of the front end of the housing is provided with a second inclined groove for guiding the cutting fluid and a through hole for air to be introduced into the interior of the housing to form an air curtain seal with the air seal nut assembly and the shaft core.

4. The air seal structure for a spindle according to claim 1, characterized in that: The sealing sleeve includes an upper end face and a lower end face; the upper end face extends radially outward to form an outer circle, and the outer circle of the upper end face and the lower end face fit with the first step provided in the locking nut cavity to conduct air passage; the upper end face of the sealing sleeve has evenly distributed circular holes for air outlet to form an air curtain seal with the shaft core and the housing.

5. The air seal structure for a spindle according to claim 1, characterized in that: The lower part of the outer wall of the locking nut is provided with a vent hole, which is used to guide the gas introduced into the housing into the sealing sleeve.

6. The air seal structure for a spindle according to claim 1, characterized in that: The second groove of the locking nut is also provided with a first process hole for cooperating with the locking fixture.

7. An assembly method for the gas seal structure according to claim 6, characterized in that: Assembly is performed using a locking fixture; the outer wall surface of the locking fixture away from the center is provided with a radially inward recessed groove for engaging with a hook-shaped torque wrench; the locking fixture also includes a second process hole, which is located on the inner side of the locking fixture and is used to insert a pin to engage with the first process hole of the locking nut of the air seal nut assembly to press the bearing; the assembly method includes the following steps: (1) Fix the housing on a three-jaw chuck, and then install the spacer assembly and the bearing into the inner cavity of the housing in sequence; (2) Align the first process hole of the locking nut and the second process hole of the locking fixture, and insert a pin into the process hole as described above, and then use the locking fixture to lock the air seal nut assembly and the outer ring of the bearing by engaging with the hook-shaped wrench through the groove; after the locking task is completed, remove the locking fixture; (3) Cold press the shaft core into the housing, the air seal nut assembly, the bearing and the spacer assembly until the second step of the shaft core is in contact with the inner ring of the bearing.

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