Self-inspection type machining center direct connection main shaft structure and using method thereof

Abstract

The invention relates to the technical field of machining center spindles, in particular to a self-inspection type machining center direct-connection spindle structure and a using method thereof, and the self-inspection type machining center direct-connection spindle structure comprises a sleeve, a pull rod and a mandrel, the pull rod slides in the mandrel; one end of the sleeve is provided with a clamping assembly for clamping a cutter, and the other end is provided with a power assembly for providing power; an airflow main path is arranged in the length direction of the pull rod; the end, close to the clamping assembly, of the mandrel is provided with a first airflow branch and a second airflow branch, and the end, away from the clamping assembly, of the mandrel communicates with an airflow main path. A first detection branch and a second detection branch are opened towards the outer wall of the sleeve along the radial direction of the mandrel; an air outlet section is communicated with the internal space of the mandrel; the pull rod is provided with a third airflow branch which is through in the radial direction. The first detector is arranged on the outer wall of the sleeve and is connected with the first detection branch to detect gas pressure; the second detector is arranged on the outer wall of the sleeve to detect gas pressure; the main shaft self-checking capability is effectively improved, and the stability and reliability of the main shaft are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of machining center spindles, and in particular to a self-checking machining center direct-connected spindle structure and a use method thereof. Background Art

[0002] In modern manufacturing, machining centers are widely used for high-precision machining of complex workpieces. One of its core components is the spindle device. Traditional spindle systems usually achieve tool clamping and tool release operations through mechanical means. Therefore, the performance of the spindle directly affects the machining efficiency and accuracy. Especially in the automated machining process, the stability and reliability of the spindle are particularly important for machining centers. Therefore, it is very necessary to detect whether the spindle is in place and whether there are any problems with its own structure.

[0003] The spindle structure in the prior art mostly uses an independent sensor module or a complex electronic detection system to monitor the spindle status; however, these systems usually have some disadvantages; the traditional spindle detection system requires the additional installation of multiple sensors and signal processing modules, which complicates the overall structure and increases the difficulty of maintenance and replacement.

[0004] Therefore, a machining center direct-connected spindle structure that can achieve real-time self-checking has become a research hotspot. Summary of the invention

[0005] The present invention provides a self-checking machining center direct-connected spindle structure and a use method thereof, which can effectively utilize airflow to detect whether the spindle is in place or has problems in different states, thereby effectively improving the stability and reliability of the spindle.

[0006] The present invention provides a self-checking machining center direct-connected spindle structure, comprising: A sleeve and a pull rod and a mandrel coaxially arranged in sequence from the sleeve axis to the sleeve radial direction; the pull rod slides in the mandrel; a clamping assembly is arranged at one end of the sleeve for clamping the tool, and a power assembly is arranged at the other end for providing power for the pull rod to move and the mandrel to rotate; The pull rod is provided with a main airflow path extending to one end of the power assembly in the length direction; The first airflow branch and the second airflow branch are provided at one end of the core shaft close to the clamping assembly; the first airflow branch and the second airflow branch are both connected to the main airflow path at one end away from the clamping assembly; the first airflow branch opens a first detection branch along the radial direction of the core shaft toward the outer wall of the sleeve, and the second airflow branch opens a second detection branch along the radial direction of the core shaft toward the outer wall of the sleeve; The first air flow branch and the second air flow branch both have an air outlet section at one end away from the main air flow path to communicate with the inner space of the core shaft; A third airflow branch is provided on the pull rod and is radially connected; A first detector is arranged on the outer wall of the sleeve and connected to the first detection branch for detecting gas pressure; A second detector is arranged on the outer wall of the sleeve and connected to the second detection branch for detecting the gas pressure; In the spindle broaching state, the main airflow path is only connected to the first airflow branch path; When the spindle is in the tool-releasing state, the main airflow path is only connected to the second airflow branch path; When the spindle is in a bladeless state, the main airflow path is only connected to the first airflow branch, and the first airflow branch is connected to the second airflow branch through the third airflow branch.

[0007] Furthermore, it also includes a fixed seat and a sliding seat which are sleeved on the pull rod; the fixed seat is fixed in a relative position to the core shaft, and the sliding seat slides on the pull rod in a direction close to or away from the fixed seat; the sliding seat has a first through hole radially opened; the fixed seat has a second through hole radially opened, the fixed seat has a first guide hole radially opened for connecting the main airflow path and the first airflow branch, and the fixed seat also has a second guide hole radially opened for connecting the main airflow path and the second airflow branch.

[0008] Furthermore, a first air flow hole is provided at one end of the pull rod contacting the fixed seat and the sliding seat, and the first air flow hole is used for connecting the main air flow path with the first guide hole and the second guide hole.

[0009] Furthermore, the first air flow hole extends a distance in the length direction of the pull rod at one end contacting the first guide hole.

[0010] Furthermore, a first sealing ring is disposed on each side of the first through hole on the sliding seat, and when the sliding seat slides, the two first sealing rings are respectively maintained on the two sides of the second through hole.

[0011] Furthermore, multiple second sealing rings are arranged at the contact point between the fixed seat and the core shaft, and one second sealing ring is arranged on each side of the second through hole; a second sealing ring is arranged between the first guide hole and the second guide hole, a second sealing ring is arranged on the side of the first guide hole away from the second through hole, and a second sealing ring is arranged on the side of the second guide hole close to the second through hole.

[0012] Furthermore, it also includes a plurality of third sealing rings arranged on the inner wall of the sleeve in contact with the core shaft; a third sealing ring is arranged on each side of the first detection branch, and a third sealing ring is arranged on each side of the second detection branch.

[0013] Furthermore, the air outlet section includes a first air outlet branch and a second air outlet branch; the first air outlet branch vertically connects the first air flow branch and the internal space of the core shaft, and the second air outlet branch obliquely connects the second air flow branch and the internal space of the core shaft.

[0014] Furthermore, a plurality of fourth sealing rings are arranged on the outer wall of the pull rod; and chamfers are provided on the inner walls where the fixed seat and the sliding seat are in contact.

[0015] The present invention also provides a method for using a direct-connected spindle of a self-checking machining center, comprising the following steps: Setting parameters: setting the air pressure thresholds P1 and P2; introducing airflow into the main airflow path from one end of the sleeve where the power assembly is set; the first detector and the second detector detect the airflow pressure in real time and display the pressure readings; Among them, 0<P1<P2; No-knife state: read the pressure readings of the first detector and the second detector. If the pressure readings are both between 0 and P1, the spindle state is normal. Broach status: Read the pressure readings of the first detector and the second detector. If the pressure reading of the first detector is between P1 and P2 and the pressure reading of the second detector is 0, the spindle status is normal. Tool release status: Read the pressure indications of the first detector and the second detector. If the pressure indication of the first detector is 0 and the pressure indication of the second detector is between P1 and P2, the spindle status is normal.

[0016] The beneficial effects of the present invention are as follows: by designing a self-checking machining center direct-connected spindle structure and a method of using the structure, dynamic switching of the airflow path is achieved in the spindle's tool pulling, tool loosening and tool-free states, and real-time detection of the airflow pressure by the first detector and the second detector is combined to achieve rapid self-checking of the spindle state, thereby improving the stability and reliability of the spindle operation; the sliding fit between the pull rod and the core shaft, and the structure of the fixed seat and the sliding seat make it unnecessary to install additional detectors inside the spindle, thereby reducing the complexity of the structure and the difficulty of maintenance; the multi-level sealing design provides reliable sealing for multiple key structures of the spindle, thereby avoiding gas leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a cross-sectional schematic diagram of the direct-connected spindle structure of the self-checking machining center in the present invention in the spindle broaching state; Figure 2 It is an enlarged schematic diagram of the cross section of the airflow path of the direct-connected spindle structure of the self-checking machining center in the spindle broaching state in the present invention; Figure 3It is an enlarged schematic diagram of the cross section of the airflow path of the direct-connected spindle structure of the self-checking machining center in the present invention when the spindle is in a tool-releasing state; Figure 4 It is an enlarged schematic diagram of the cross section of the airflow path of the direct-connected spindle structure of the self-checking machining center in the present invention when the spindle is in a state without a tool; Figure numerals: 1. sleeve; 11. clamping assembly; 13. first detector; 14. second detector; 15. third sealing ring; 2. pull rod; 21. main air flow path; 22. third air flow branch; 23. first air flow hole; 24. fourth sealing ring; 3. core shaft; 31. first air flow branch; 311. first detection branch; 32. second air flow branch; 321. second detection branch; 33. air outlet section; 331. first air outlet branch; 332. second air outlet branch; 4. fixed seat; 41. second through hole; 42. first guide hole; 43. second guide hole; 44. second sealing ring; 5. sliding seat; 51. first through hole; 52. first sealing ring; 6. chamfer. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0020] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by “center”, “up”, “down”, “left”, “right”, “vertical”, “horizontal”, “inside” and “outside”, etc., are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed 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, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] A self-checking machining center directly connected to the spindle structure, such as Figures 1 to 4 As shown, including: A sleeve 1 and a pull rod 2 and a mandrel 3 are coaxially arranged in sequence from the axis of the sleeve 1 to the radial direction of the sleeve 1; the pull rod 2 slides in the mandrel 3; a clamping assembly 11 is arranged at one end of the sleeve 1, which contacts one end of the pull rod 2 and is used to clamp the tool, and a power assembly is arranged at the other end, which contacts the other end of the pull rod 2 and is used to provide power for the pull rod 2 to move and the mandrel 3 to rotate; The pull rod 2 is provided with a main airflow path 21 extending to one end of the power assembly in the length direction, so as to facilitate the injection of airflow into the main airflow path 21 from this end to avoid collision with the tool; The end of the core shaft 3 close to the clamping assembly 11 is provided with a first airflow branch 31 and a second airflow branch 32; the ends of the first airflow branch 31 and the second airflow branch 32 away from the clamping assembly 11 are both connected to the main airflow path 21; the first airflow branch 31 opens a first detection branch 311 along the radial direction of the core shaft 3 toward the outer wall of the sleeve 1, and the second airflow branch 32 opens a second detection branch 321 along the radial direction of the core shaft 3 toward the outer wall of the sleeve 1; The first air flow branch 31 and the second air flow branch 32 are both provided with an air outlet section 33 at one end away from the main air flow path 21 to communicate with the inner space of the core shaft 3; A third airflow branch 22 is provided on the pull rod 2 and is radially connected to the first airflow branch 31 and the second airflow branch 32; The first detector 13 is arranged on the outer wall of the sleeve 1 and connected to the first detection branch 311, and is used to detect the gas pressure; The second detector 14 is arranged on the outer wall of the sleeve 1 and connected to the second detection branch 321, and is used to detect the gas pressure; Two detectors detect the air flow pressure in real time, providing a reliable numerical basis for judging the spindle status; When the spindle is normal and the tie rod 2 and the mandrel 3 are not damaged or bent: In the spindle broaching state, if Figure 2 As shown, the main airflow path 21 is only connected to the first airflow branch 31; after broaching, the tool is clamped by the clamping assembly 11, and the inner wall of the core shaft 3 has a certain inclination angle to fit the tool, and the air outlet section 33 connected to the first airflow branch 31 is also blocked by the tool, and the air cannot be discharged; therefore, at this time, the first detector 13 will detect that the air pressure increases, while the second detector 14 is not connected to the airflow, and the air pressure cannot be detected, and the reading is 0; When the spindle is in the tool release state, Figure 3 As shown, the main airflow path 21 is only connected to the second airflow branch 32, and no airflow passes through the first airflow branch 31, so the first detector 13 cannot detect the air pressure, and the air pressure reading is 0; and the air outlet section 33 of the second airflow branch 32 on the inner wall of the core shaft 3 will be pressed by an inclined surface of the clamping component 11 because the clamping component 11 is pushed by the pull rod 2 to loosen the knife, so that the second detector 14 detects that the air pressure increases, and the reading reaches a preset threshold range; When the spindle is without a tool, Figure 4 As shown, the main airflow path 21 is only connected to the first airflow branch 31, and the first airflow branch 31 is connected to the second airflow branch 32 through the third airflow branch 22; the air outlet section 33 will not be blocked due to the lack of influence of the tool, and can discharge air normally; the airflow in the main airflow path 21 reaches the first detector 13 along the route of the first airflow branch 31 and the first detection branch 311, and also reaches the second detector 14 along the route of the first airflow branch 31, the third airflow branch 22, the second airflow branch 32, and the second detection branch 321; because the air outlet section 33 also divides a part of the airflow, the readings of the air pressure detected by the two detectors will not be very large; If the air pressure reading does not match the above situation, then the spindle has been damaged, misaligned, bent, etc., resulting in the air paths not being able to connect smoothly. At this time, maintenance work is required.

[0023] Compared with the traditional detection method relying on mechanical devices, the present spindle realizes multi-state detection function through dynamic switching of the main airflow path 21 and the branch path design, without adding complex electronic detection systems or independent electrical components, thereby simplifying the system structure, reducing the wear of the spindle under high-speed operation, and reducing the risk of misoperation.

[0024] Preferably, it also includes a fixed seat 4 and a sliding seat 5 sleeved on the pull rod 2; the fixed seat 4 is fixed relative to the core shaft 3, and the sliding seat 5 slides on the pull rod 2 toward or away from the fixed seat 4; the sliding seat 5 radially opens a first through hole 51; the fixed seat 4 radially opens a second through hole 41, the fixed seat 4 radially opens a first guide hole 42 for connecting the main airflow path 21 and the first airflow branch 31, and the fixed seat 4 further opens a second guide hole 43 for connecting the main airflow path 21 and the second airflow branch 32; The fixed seat 4 serves as a branch node of the main airflow path 21, and distributes the airflow to different airflow branches through the first guide hole 42 and the second guide hole 43, while ensuring the stability of the structure through a fixed design; the sliding seat 5 realizes a complex airflow path switching function through a simple sliding action, meeting the different needs of the three states of spindle tool pulling, tool loosening and toolless, forming a completely enclosed airflow path, avoiding airflow leakage, and improving detection accuracy and operational reliability; moreover, the fixed seat 4 and the sliding seat 5 have a clear design structure, a small number of components, and a simplified manufacturing process, and cooperate to avoid high-frequency wear of complex mechanical components, making it easy to replace worn parts or clean the system.

[0025] A first air flow hole 23 is provided at one end of the pull rod 2 that contacts the fixed seat 4 and the sliding seat 5. The first air flow hole 23 is used for connecting the main air flow path 21 with the first guide hole 42 and the second guide hole 43. By providing an air flow hole on the pull rod 2, the design of additional independent air flow channels is reduced, and the air flow management function is concentrated inside the pull rod 2, which simplifies the complexity of the air path layout and improves the overall stability of the air flow path. The first air flow hole 23 and the third air flow branch 22 respectively undertake different connection tasks in the spindle's tool pulling, tool loosening and tool-free states, and are the core of the spindle's self-inspection work.

[0026] Preferably, the first air flow hole 23 extends a certain distance along the length direction of the pull rod 2 at the end that contacts the first guide hole 42, thereby forming a groove on the surface of the pull rod 2; when the spindle is in the knife-free state, the pull rod 2 is in a state closest to the power assembly. At this time, in order to direct the airflow of the main air flow path 21 into the first main air flow path 21 without opening an additional air flow path, the above-mentioned effect can be achieved more conveniently and quickly by extending the first air flow hole 23 for a certain distance.

[0027] In some embodiments of the present invention, a first sealing ring 52 is provided on each side of the first through hole 51 on the sliding seat 5 to seal the first through hole 51 from both sides, and when the sliding seat 5 slides, the two first sealing rings 52 are respectively maintained on both sides of the second through hole 41; the first through hole 51 and the second through hole 41 are connected to the third air flow branch 22, and the first sealing ring 52 is maintained on both sides of the through hole, thereby avoiding the possibility that the first sealing ring 52 passes over the second through hole 41 when the sliding seat 5 slides, causing the first sealing ring 52 to pop out and enter the second through hole 41.

[0028] A plurality of second sealing rings 44 are arranged at the contact point between the fixed seat 4 and the core shaft 3, and a second sealing ring 44 is arranged on each side of the second through hole 41; a second sealing ring 44 is arranged in the middle of the first guide hole 42 and the second guide hole 43, a second sealing ring 44 is arranged on the side of the first guide hole 42 away from the second through hole 41, and a second sealing ring 44 is arranged on the side of the second guide hole 43 close to the second through hole 41; a static seal is provided between the fixed seat 4 and the core shaft 3 to prevent leakage of airflow in the main airflow path 21, the first guide hole 42 and the second guide hole 43; it is ensured that the airflow always flows along the predetermined path during the guide process without being disturbed by the external environment, thereby improving the overall stability of the main shaft structure.

[0029] It also includes a plurality of third sealing rings 15 arranged on the inner wall where the sleeve 1 contacts the core shaft 3; a third sealing ring 15 is arranged on each side of the first detection branch 311, and a third sealing ring 15 is arranged on each side of the second detection branch 321; because the core shaft 3 will rotate inside the sleeve 1, the third sealing ring 15 does not adopt an ordinary sealing ring, but adopts a shaft seal to achieve line sealing, and the opening faces the detection branch, so as to seal the two detection branches to prevent air leakage and improve the accuracy of the detector in detecting air pressure.

[0030] In some embodiments of the present invention, the air outlet section 33 includes a first air outlet branch 331 and a second air outlet branch 332; the first air outlet branch 331 vertically connects the first air outlet branch 31 and the internal space of the core shaft 3, so that the path of the first air outlet branch 331 at the end of the core shaft 3 farthest from the power assembly is the shortest, reducing the impact on the stability of the core shaft 3, and can further blow the foreign matter blown away by the second air outlet branch 332 away from the clamping assembly 11; the second air outlet branch 332 obliquely connects the second air outlet branch 32 and the internal space of the core shaft 3, and when the spindle is in a knife-free state, it can better fit the clamping assembly 11, and when the spindle is in a knife-free state, it can clean the foreign matter on the surface of the clamping assembly 11 caused by the operation of the spindle, and can also help the movement of the clamping assembly 11, so that the pull rod 2 moves to a state closest to the power assembly.

[0031] When the air outlet section 33 sprays air outward, an air curtain can be formed at the opening and gap of the main shaft, effectively isolating interference from the external environment such as dust, cutting fluid and other impurities, while protecting the normal operation of the internal airflow detection structure.

[0032] A plurality of fourth sealing rings 24 are arranged on the outer wall of the pull rod 2. The fourth sealing rings 24 are arranged on both sides of the path through which the air flows. The fourth sealing ring 24 is also arranged at the contact point of the outer wall when the pull rod 2 slides in the core shaft 3, so as to ensure the air tightness of the whole main shaft structure. The inner walls where the fixed seat 4 and the sliding seat 5 are in contact are both provided with chamfers 6. When the pull rod 2 slides, the fixed seat 4 and the sliding seat 5 are not always in contact with each other to produce a gap. A fourth sealing ring 24 will pass through this gap. The chamfer 6 can help this sealing ring to move better with the pull rod 2 without being trapped in the gap.

[0033] The present invention also provides a method for using a direct-connected spindle of a self-checking machining center, comprising the following steps: Setting parameters: setting the air pressure thresholds P1 and P2; introducing airflow into the main airflow path 21 from one end of the sleeve 1 where the power assembly is set, and starting the self-test; the first detector 13 and the second detector 14 detect the airflow pressure in real time and display the pressure readings; Among them, 0<P1<P2; No-knife state: read the pressure readings of the first detector 13 and the second detector 14. If the pressure readings are both between 0 and P1, the spindle state is normal. Broach status: read the pressure readings of the first detector 13 and the second detector 14. If the pressure reading of the first detector 13 is between P1 and P2 and the pressure reading of the second detector 14 is 0, the spindle status is normal. Tool release status: read the pressure readings of the first detector 13 and the second detector 14. If the pressure reading of the first detector 13 is 0 and the pressure reading of the second detector 14 is between P1 and P2, the spindle status is normal. The spindle can be switched from the tool-releasing state to the tool-free state or the tool-pulling state at will without any fixed order. After switching to another state, the spindle can perform self-inspection through the first detector 13 and the second detector 14.

[0034] The design of the above-mentioned method of use does not require external intervention. By real-time monitoring of the pressure values ​​of the first detector 13 and the second detector 14, it automatically detects real-time pressure changes and quickly determines whether the working state of the spindle is normal, thereby avoiding errors caused by human operation or visual judgment, improving detection accuracy and reliability, and reducing downtime. It can promptly detect problems in abnormal situations such as pressure out of range or insufficient pressure, and prevent damage to the spindle caused by faulty operation.

[0035] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A self-checking machining center direct-connected spindle structure, characterized in that: include: A sleeve (1) and a pull rod (2) and a core shaft (3) coaxially arranged in sequence from the axis of the sleeve (1) toward the sleeve (1) in a radial direction; the pull rod (2) slides in the core shaft (3); a clamping assembly (11) is arranged at one end of the sleeve (1) for clamping a tool, and a power assembly is arranged at the other end for providing power for the pull rod (2) to move and the core shaft (3) to rotate; The pull rod (2) is provided with a main airflow path (21) extending to one end of the power assembly in the length direction; The end of the core shaft (3) close to the clamping assembly (11) is provided with a first airflow branch (31) and a second airflow branch (32); the ends of the first airflow branch (31) and the second airflow branch (32) away from the clamping assembly (11) are both connected to the main airflow path (21); the first airflow branch (31) is provided with a first detection branch (311) along the radial direction of the core shaft (3) toward the outer wall of the sleeve (1), and the second airflow branch (32) is provided with a second detection branch (321) along the radial direction of the core shaft (3) toward the outer wall of the sleeve (1); The first air flow branch (31) and the second air flow branch (32) are both provided with an air outlet section (33) at an end away from the main air flow path (21) to communicate with the internal space of the core shaft (3); The pull rod (2) is provided with a third airflow branch (22) which penetrates radially; A first detector (13), arranged on the outer wall of the sleeve (1), connected to the first detection branch (311), and used for detecting gas pressure; A second detector (14), arranged on the outer wall of the sleeve (1), connected to the second detection branch (321), and used for detecting gas pressure; In the spindle broaching state, the main airflow path (21) is only connected to the first airflow branch path (31); When the spindle is in a tool-releasing state, the main airflow path (21) is connected only to the second airflow branch path (32); When the spindle is in a bladeless state, the main airflow path (21) is connected only to the first airflow branch path (31), and the first airflow branch path (31) is connected to the second airflow branch path (32) via the third airflow branch path (22).

2. The self-checking machining center direct-connected spindle structure according to claim 1 is characterized in that: It also includes a fixed seat (4) and a sliding seat (5) which are sleeved on the pull rod (2); the fixed seat (4) is fixed in relative position to the core shaft (3), and the sliding seat (5) slides on the pull rod (2) in a direction approaching or away from the fixed seat (4); the sliding seat (5) radially opens a first through hole (51); the fixed seat (4) radially opens a second through hole (41), the fixed seat (4) radially opens a first guide hole (42) for connecting the main airflow path (21) and the first airflow branch (31), and the fixed seat (4) also radially opens a second guide hole (43) for connecting the main airflow path (21) and the second airflow branch (32).

3. The self-checking machining center direct-connected spindle structure according to claim 2 is characterized in that: A first air flow hole (23) is provided at one end of the pull rod (2) that contacts the fixed seat (4) and the sliding seat (5), and the first air flow hole (23) is used for connecting the main air flow path (21) with the first guide hole (42) and the second guide hole (43).

4. The self-checking machining center direct-connected spindle structure according to claim 3 is characterized in that: The first air flow hole (23) extends a distance in the length direction of the pull rod (2) at one end contacting the first guide hole (42).

5. The self-checking machining center direct-connected spindle structure according to claim 3 is characterized in that: A first sealing ring (52) is respectively arranged on both sides of the first through hole (51) on the sliding seat (5), and when the sliding seat (5) slides, the two first sealing rings (52) are respectively maintained on both sides of the second through hole (41).

6. The self-checking machining center direct-connected spindle structure according to claim 3 is characterized in that: A plurality of second sealing rings (44) are arranged at the contact point between the fixing seat (4) and the core shaft (3), and one second sealing ring (44) is arranged on each side of the second through hole (41); one second sealing ring (44) is arranged between the first flow guide hole (42) and the second flow guide hole (43), one second sealing ring (44) is arranged on the side of the first flow guide hole (42) away from the second through hole (41), and one second sealing ring (44) is arranged on the side of the second flow guide hole (43) close to the second through hole (41).

7. The self-checking machining center direct-connected spindle structure according to claim 1 is characterized in that: It also includes a plurality of third sealing rings (15) arranged on the inner wall of the sleeve (1) in contact with the core shaft (3); one third sealing ring (15) is arranged on each side of the first detection branch (311), and one third sealing ring (15) is arranged on each side of the second detection branch (321).

8. The self-checking machining center direct-connected spindle structure according to claim 1 is characterized in that: The air outlet section (33) comprises a first air outlet branch (331) and a second air outlet branch (332); the first air outlet branch (331) vertically connects the first air flow branch (31) and the internal space of the core shaft (3), and the second air outlet branch (332) obliquely connects the second air flow branch (32) and the internal space of the core shaft (3).

9. The self-checking machining center direct-connected spindle structure according to claim 2 is characterized in that: The outer wall of the pull rod (2) is provided with a plurality of fourth sealing rings (24); and the inner walls where the fixed seat (4) and the sliding seat (5) are in contact are both provided with chamfers (6).

10. A method for using a direct-connected spindle in a self-checking machining center, characterized in that: The self-checking machining center direct-connected spindle structure as claimed in any one of claims 1 to 9 comprises the following steps: Setting parameters: setting the air pressure thresholds P1 and P2; introducing airflow into the main airflow path (21) from one end of the sleeve (1) where the power assembly is arranged; the first detector (13) and the second detector (14) detect the airflow pressure in real time and display the pressure readings; Among them, 0<P1<P2; No-knife state: read the pressure readings of the first detector (13) and the second detector (14). If the pressure readings are both between 0 and P1, the spindle state is normal. Broach status: read the pressure readings of the first detector (13) and the second detector (14). If the pressure reading of the first detector (13) is between P1 and P2 and the pressure reading of the second detector (14) is 0, the spindle status is normal; Tool release status: read the pressure readings of the first detector (13) and the second detector (14). If the pressure reading of the first detector (13) is 0 and the pressure reading of the second detector (14) is between P1 and P2, the spindle status is normal.

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