Tool changing spindle with built-in nitrogen and tool changing device

Abstract

The utility model relates to the field of machining, and discloses a tool changing spindle with built-in nitrogen and a tool changing device, the tool changing spindle comprises an outer shell, an inner shell, a pull rod and an end cover, the inner shell is rotatably connected with the outer shell, an outer cavity is arranged in the inner shell, and high-pressure nitrogen is arranged in the outer cavity; the pull rod is arranged in the inner shell, and the pull rod is used for clamping the cutting knife to realize replacement of the cutting knife; the end cover is arranged on the inner shell in a sleeved mode, the end cover can slide relative to the inner shell under the action of external force, and when the end cover moves downwards, the end cover abuts against the pull rod and pushes the pull rod to move. According to the utility model, the cutting knife is replaced by compressing high-pressure nitrogen; the device has the characteristics of small size and large elasticity.

Description

Technical Field

[0001] The utility model relates to the technical field of mechanical processing, in particular to a tool changing spindle and a tool changing device with built-in nitrogen. Background Art

[0002] In the field of machining, especially in automated production lines and CNC machine tools, rapid blade replacement is crucial for improving production efficiency and reducing processing costs. Traditionally, blade replacement requires manual operation, a time-consuming process that can easily lead to blade damage or reduced precision due to operator error. With the advancement of industrial automation technology, tool-changing spindles have emerged. They enable quick and accurate blade replacement without manual intervention, significantly improving machining efficiency and quality.

[0003] Existing tool-changing spindles are often connected to a pull rod via a spring or piston rod. Tool changes are achieved by extending and retracting the pull rod. This complex structure is difficult to maintain and expensive. Furthermore, with the ever-increasing demand for miniaturized cutting devices in woodworking machinery, current tool-changing devices cannot meet this demand. Therefore, improvements to existing tool-changing spindles are urgently needed. Utility Model Content

[0004] In response to the shortcomings of the existing technology, the present invention provides a tool changing spindle and tool changing device with built-in nitrogen, which realizes the replacement of cutting blades by compressing high-pressure nitrogen; it has the characteristics of small size and high elasticity. The implementation method of this technical solution is as follows:

[0005] A tool-changing spindle with built-in nitrogen comprises: an outer shell, an inner shell, a pull rod and an end cover, wherein the inner shell is rotatably connected to the outer shell, an outer cavity is provided in the inner shell, and high-pressure nitrogen is configured inside the outer cavity; the pull rod is provided in the inner shell, and the pull rod is used to clamp the cutting knife to achieve the replacement of the cutting knife; the end cover is sleeved on the inner shell, and the end cover can slide relative to the inner shell under the action of external force. When the end cover moves downward, the end cover abuts against the pull rod and pushes the pull rod to move.

[0006] Preferably, the outer cavity is formed by the space between the inner wall of the inner shell and the outer wall of the pull rod, the pull rod is provided with an inner cavity, and the inner cavity and the outer cavity are communicated.

[0007] Preferably, a valve seat is also provided inside the pull rod, and an air valve is installed on the valve seat. The air nozzle of the air valve is placed in the inner cavity. The air valve injects high-pressure nitrogen into the inner cavity through an external air source. A channel is provided between the inner cavity and the outer cavity to enable high-pressure nitrogen to enter the outer cavity from the inner cavity.

[0008] Preferably, a plurality of steel balls are further included, a plurality of ball holes are arranged at one end of the pull rod, each of the plurality of ball holes is used for cooperating with the steel balls to realize clamping and disengaging of the pull rod to the cutting knife.

[0009] Preferably, a first sealing ring is arranged at both ends of the outer cavity, and a sealing cover is mounted at both ends of the pull rod.

[0010] Preferably, a coupling is further included, the coupling is fixedly connected with the inner shell, and a spring is arranged between the coupling and the end cover.

[0011] Preferably, a first limiting block is arranged between the inner shell and the pull rod, the first limiting block is clamped with the inner wall of the inner shell, a second limiting block is arranged inside the inner shell, and the second limiting block is fixedly connected with the inner shell or integrally formed.

[0012] Preferably, the inner shell is provided with a knife placing chamber for accommodating the cutting knife, and a ball cavity is arranged in the knife placing chamber.

[0013] Preferably, a second sealing ring is arranged between the inner shell and the pull rod, the second sealing ring is located above the knife placing chamber, and a third sealing ring is arranged between the valve seat and the pull rod.

[0014] The application also relates to a knife changing device, which comprises the built-in nitrogen knife changing spindle and the hydraulic driving device, the hydraulic driving device comprises a cylinder body and a piston rod, the piston rod is sleeved in the cylinder body, an oil cavity is formed between the outer wall of the piston rod and the inner wall of the cylinder body, the cylinder body is provided with an oil inlet hole, hydraulic oil is injected into the oil cavity through an external oil pipe, in a working state, the hydraulic oil in the oil cavity generates oil pressure to drive the piston rod to move downward, so that the piston rod and the end cover abut against each other, thereby driving the pull rod to move downward.

[0015] Compared with the prior art, the application has the following beneficial effects:

[0016] The tool changing main shaft of the present technical solution injects high-pressure nitrogen into the gas valve through an external gas source before use, the nitrogen enters the inner cavity of the pull rod through the gas nozzle of the gas valve, and then enters the outer cavity through the channel between the inner cavity and the outer cavity; at this time, the pull rod is in a state of retracting upward, the steel ball cooperates with the pull rod to block the neck of the cutting tool in the ball hole, and the cutting tool is clamped. When the cutting tool is replaced, the end cover is moved downward under external pressure. The end cover abuts against the pull rod and pushes the pull rod to move downward; as the pull rod moves downward, the steel ball also moves downward in the ball cavity; at this time, part of the steel ball is in the ball cavity, and the other part is still in the ball hole, so that the steel ball no longer blocks the neck of the cutting tool, and the cutting tool can be smoothly withdrawn from the tool chamber; in this process, the high-pressure nitrogen in the outer cavity is compressed, the volume is reduced, and the energy is stored; when the new cutting tool enters the tool chamber, the external pressure of the end cover is removed; the high-pressure nitrogen in the outer cavity expands, the volume is restored, and the elastic pressure is generated; the pull rod is pushed to retract upward, and the pull rod cooperates with the steel ball to drive the new cutting tool to move upward; in this process, part of the steel ball will block the neck of the cutting tool again, so that the cutting tool will not fall from the tool chamber, thereby clamping the cutting tool again and realizing the replacement of the cutting tool.

[0017] In summary, the tool changing main shaft of the present technical solution provides strong elastic pressure through the compression and expansion of high-pressure nitrogen, quickly pushes the pull rod to move, realizes the quick replacement of the cutting tool, greatly shortens the tool changing time, and improves the working efficiency of the equipment; at the same time, through the above structural design, the tool changing main shaft of the present embodiment is smaller in size, so that the tool changing main shaft can be adapted to the equipment with limited space. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0019] Figure 1 It is a structural schematic view of the tool changing main shaft of the present utility model;

[0020] Figure 2 It is an explosion view of the tool changing main shaft of the present utility model;

[0021] Figure 3 It is a half-sectional view of the present utility model;

[0022] Figure 4 It is a sectional view of the present utility model;

[0023] Figure 5 It is a structural schematic view of the pull rod of the present utility model;

[0024] Figure 6 It is a structural schematic view of the hydraulic drive device of the present utility model;

[0025] Figure 7 It is a structural diagram of the application scenario of the utility model;

[0026] Figure 8 for Figure 3 Enlarged view of point A in the middle.

[0027] Description of reference numerals: 100, cutting knife; 101, neck; 200, protective shell; 300, driving motor; 400, turbine; 500, dust cover;

[0028] 1. Housing; 11. Bearing;

[0029] 2. Inner shell; 21. Outer cavity; 211. First sealing ring; 22. First stop block; 23. Second stop block; 24. Second sealing ring; 25. Blade chamber; 251. Ball chamber;

[0030] 3. Pull rod; 31. Inner cavity; 32. Valve seat; 321. Third sealing ring; 33. Air valve; 34. Sealing cover; 35. Ball hole;

[0031] 4. End cover; 41. Spring; 42. Support part;

[0032] 5. Coupling;

[0033] 6. Steel ball;

[0034] 7. Hydraulic drive device; 71. Cylinder body; 711. Oil chamber; 712. Oil inlet hole; 72. Piston rod. DETAILED DESCRIPTION

[0035] The following diagrams illustrate various embodiments of the present invention. For clarity, many practical details will be included in the following description. However, it should be understood that these practical details are not intended to limit the present invention. In other words, in some embodiments of the present invention, these practical details are not essential. Furthermore, to simplify the drawings, some commonly used structures and components are depicted in a simplified schematic manner.

[0036] It should be noted that all directional indications such as up, down, left, right, front, back, etc. in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components in a certain specific posture as shown in the accompanying drawings. If the specific posture changes, the directional indication will also change accordingly.

[0037] In addition, in the present invention, descriptions such as "first" and "second" are only used for descriptive purposes and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish between parts or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0039] This application relates to a tool changing spindle with built-in nitrogen, which is a key component in the field of mechanical processing, specifically a key component of a tool changing device, see Figure 7 This type of blade changing device is typically installed on a cutting device. One of the functions of the cutting device is to provide a dust collection effect. Its application scenario is to promptly clean up dust or debris from wood cutting. The cutting device includes a protective housing 200, a drive motor 300, a turbine 400, a dust hood 500, and a blade changing device. The blade changing device is mounted on the cutting blade 100. The blade changing device is mounted on the front axle end of the drive motor 300, and the turbine 400 is mounted on the rear axle end. The protective housing 200 has an air duct, and the dust hood 500 is arranged around the cutting blade 100. During use, the wood (or board) to be cut is placed on a panel. The cutting blade 100 contacts the board and performs a cutting action, which generates dust or debris. Under the action of the turbine 400, a large negative pressure is generated in the dust hood 500 and the air duct, forming a suction force, thereby promptly sucking away and discharging the dust or debris generated by cutting.

[0040] The above is a description of the application scenario of the tool changing spindle of this application, to facilitate understanding of the purpose of this application. It can also be used in other scenarios, which will not be described here one by one.

[0041] Some embodiments of the present application are described in detail. In the absence of conflict, the following embodiments and features of the embodiments can be combined with each other.

[0042] The embodiment of the present application provides a tool changing spindle with built-in nitrogen, such as Figure 1-4As shown, it comprises: a shell 1, an inner shell 2, a pull rod 3 and an end cover 4, the inner shell 2 is rotatably connected with the shell 1, the inner shell 2 is provided with an outer cavity 21 inside, the inner cavity 21 is configured with high-pressure nitrogen gas inside; the pull rod 3 is arranged in the inner shell 2, the pull rod 3 is used for clamping the cutting knife 100 to realize the replacement of the cutting knife 100; the end cover 4 is sleeved on the inner shell 2, the end cover 4 can slide relative to the inner shell 2 under the action of external force, when the end cover 4 moves downward, the end cover 4 abuts against the pull rod 3 and pushes the pull rod 3 to move.

[0043] In some embodiments, referring to Figure 3-4 , the outer cavity 21 is composed of the space between the inner wall of the inner shell 2 and the outer wall of the pull rod 3, the pull rod 3 is provided with an inner cavity 31 inside, the inner cavity 31 and the outer cavity 21 are communicated. The pull rod 3 is further provided with a valve seat 32 inside, the valve seat 32 is installed with a gas valve 33, the gas nozzle of the gas valve 33 is placed in the inner cavity 31, the inner cavity 31 is injected with high-pressure nitrogen gas by the external gas source through the gas valve 33, and a channel is arranged between the inner cavity 31 and the outer cavity 21 to realize the high-pressure nitrogen gas from the inner cavity 31 into the outer cavity 21.

[0044] Specifically, the gas valve 33 is located between the knife changing chamber 25 and the inner cavity 31; it should be noted that before the tool changing spindle is used, the staff has injected high-pressure nitrogen gas into the inner cavity 31 and the outer cavity 21 through the external gas source, a channel is arranged between the outer cavity 21 and the inner cavity 31 to realize the high-pressure nitrogen gas from the inner cavity 31 into the outer cavity 21; when the tool changing spindle works, the pull rod 3 is in the state of retracting upward, the end cover 4 is abutted against the pull rod 3 under the external pressure, thereby pushing the pull rod 3 to move downward, when the pull rod 3 moves downward, the cutting knife 100 will be pushed out of the tool changing spindle (that is, the cutting knife 100 is separated from the pull rod 3); at this time, the high-pressure nitrogen gas in the outer cavity 21 is compressed, so that the volume of the high-pressure nitrogen gas becomes smaller; when the new cutting knife 100 enters the tool changing spindle, the external pressure is removed, the high-pressure nitrogen gas expands, the volume of the outer cavity 21 recovers, so a certain elastic pressure is obtained, thereby pushing the pull rod 3 upward to assemble the cutting knife 100, and the tool changing action is completed. The above utilization of high-pressure nitrogen gas, that is, constitutes a nitrogen gas spring. The above external pressure is derived from other driving parts matched with the device, which will be described in subsequent embodiments.

[0045] In some embodiments, referring to Figure 3-4 , the outer cavity 21 is provided with a first sealing ring 211 at both ends, the pull rod 3 is installed with a sealing cover 34 at both ends to seal both ends of the inner cavity 31, the functions of the first sealing ring 211 and the sealing cover 34 are to avoid the leakage of high-pressure nitrogen gas in the inner cavity 31 and the outer cavity 21.

[0046] In some embodiments, referring to Figure 4A first limit block 22 is provided between the inner shell 2 and the pull rod 3, and the first limit block 22 is clamped with the inner wall of the inner shell 2; the inner wall of the inner shell 2 is provided with a groove, and the surface of the first limit block 22 is provided with a protrusion, and the protrusion cooperates with the groove to achieve clamping; a second limit block 23 is provided inside the inner shell 2, and the second limit block 23 is fixedly connected to the inner shell 2 or integrally formed; the first limit block 22 and the second limit block 23 are used to effectively limit the movement range of the pull rod 3 in the inner shell 2, preventing the pull rod 3 from excessive movement under the action of external force, thereby avoiding damage to the pull rod 3 or the inner shell 2.

[0047] In some embodiments, see Figure 1-2 , and also includes a coupling 5, which is fixedly connected to the inner shell 2, and a spring 41 is provided between the coupling 5 and the end cover 4; the coupling 5 is connected to the drive motor 300, and the drive motor 300 drives the tool changing spindle to rotate, thereby driving the cutting knife 100 to rotate and cut, thereby realizing the cutting function.

[0048] Specifically, one end of the spring 41 abuts against the coupling 5, and the other end abuts against the end cover 4; the purpose of providing the spring 41 is to prevent the end cover 4 from shaking significantly when the inner shell 2 drives the end cover 4 to rotate, so that the end cover 4 is stabilized above the pull rod 3; at the same time, it is prevented from rebounding when the tool is changed, causing the end cover 4 to shake up and down; it has the effect of stabilizing the structure of the end cover 4. Furthermore, the end cover 4 is provided with a support portion 42, the cross-sectional area of ​​the support portion 42 is larger than the cross-sectional area of ​​the coupling 5, and the support portion 42 is used to withstand external pressure so that the end cover 4 can move downward smoothly.

[0049] In some embodiments, see Figure 3-5 , and also includes a number of steel balls 6. A number of ball holes 35 are correspondingly provided at one end of the pull rod 3, and each of the several ball holes 35 is used to cooperate with the steel ball 6 to realize the clamping and disengagement of the pull rod 3 on the cutting knife 100; specifically, the ball hole 35 includes a straight section and a narrowed section in the axial direction; the straight section is close to the outer wall of the pull rod 3, and the diameter of the straight section is larger than the diameter of the steel ball 6. The purpose of setting the straight section is to enable the steel ball 6 to slide smoothly in the ball hole 35; the narrowed section is close to the inner wall of the pull rod 3, and the diameter of the narrowed section is smaller than the diameter of the steel ball 6, so as to prevent the steel ball 6 from falling into the interior of the pull rod 3, causing the pull rod 3 to be unable to clamp the cutting knife 100, thereby failing to realize the cutting function.

[0050] In some embodiments, see Figure 3-5 and Figure 8The inner shell 2 is provided with a knife chamber 25 for accommodating the cutting knife 100. The knife chamber 25 is used to install the cutting knife 100. A ball cavity 251 is provided in the knife chamber 25. Specifically, the diameter of the cross section of the ball cavity 251 is larger than the diameter of the cross section of the cavity at the bottom of the pull rod 3. The ball cavity 251 is located below the outer cavity 21 and the inner cavity 31. The two ends of the ball cavity 251 are arc-shaped, and its shape facilitates the steel ball 6 to smoothly enter and exit the ball cavity 251.

[0051] More specifically, when the tool change spindle drives the cutting blade 100, the bottom of the pull rod 3 is located above the ball cavity 251. At this time, the steel ball 6 is mounted on the ball hole 35 and is stuck in the neck 101 of the cutting blade 100, thereby clamping the cutting blade 100. When the tool change spindle performs the tool change operation, the pull rod 3 drives the cutting blade 100 downward. As the pull rod 3 moves downward, the steel ball 6 originally matched with the ball hole 35 also moves downward with the pull rod 3. When the bottom of the pull rod 3 moves downward to the position of the ball cavity 251, the steel ball 6 also moves downward into the ball cavity 251. At this time, a part of the steel ball 6 is located in the rolling ball cavity 251, while the other part is still in the ball hole 35, so that the steel ball 6 no longer jams the neck 101 of the cutting knife 100, and the cutting knife 100 can be smoothly withdrawn from the knife placement chamber 25; when the new cutting knife 100 enters the knife placement chamber 25, the pull rod 3 will cooperate with the steel ball 6 to drive the new cutting knife 100 to move upward; in this process, a part of the steel ball 6 will re-jam the neck 101 of the cutting knife 100, so that the cutting knife 100 will not fall from the knife placement chamber 25, thereby clamping the cutting knife 100 again and realizing the replacement of the cutting knife 100.

[0052] In some embodiments, see Figure 4 A second sealing ring 24 is provided between the inner shell 2 and the pull rod 3, and the second sealing ring 24 is located above the knife chamber 25; the second sealing ring 24 is used to further seal the outer cavity 21 to prevent nitrogen leakage and prevent dust and the like from entering the outer cavity 21; a third sealing ring 321 is provided between the valve seat 32 and the pull rod 3, and the third sealing ring 321 is used to further seal the inner cavity 31 and prevent dust and the like from entering the inner cavity 31.

[0053] In some embodiments, see Figure 4 A bearing 11 is provided between the outer shell 1 and the inner shell 2. Specifically, a bearing 11 is provided at both ends between the outer shell 1 and the inner shell 2, and the outer shell 1 and the inner shell 2 are rotatably connected through the bearing 11.

[0054] The working principle of the tool changing spindle with built-in nitrogen in this embodiment is as follows:

[0055] Before using the tool-changing spindle of this technical solution, high-pressure nitrogen is injected into the air valve 33 from an external air source. The nitrogen enters the inner cavity 31 of the pull rod 3 through the air nozzle of the air valve 33, and then enters the outer cavity 21 through the passage between the inner cavity 31 and the outer cavity 21. At this time, the pull rod 3 is in an upward retracted state, and the steel ball 6 cooperates with the pull rod 3 in the ball hole 35 to clamp the neck 101 of the cutting blade 100, thereby clamping the cutting blade 100. When replacing the cutting blade 100, external pressure is applied to move the end cap 4 downward. The end cover 4 abuts against the pull rod 3, pushing the pull rod 3 to move downward; as the pull rod 3 moves downward, the steel ball 6 simultaneously moves downward into the rolling ball cavity 251; at this time, a portion of the steel ball 6 is located in the rolling ball cavity 251, while the other portion is still in the ball hole 35, so that the steel ball 6 no longer gets stuck in the neck 101 of the cutting knife 100, and the cutting knife 100 can be smoothly withdrawn from the knife chamber 25; in this process, the high-pressure nitrogen in the outer cavity 21 is compressed, the volume becomes smaller, and energy is stored. When the new cutting knife 100 enters the knife placement chamber 25, the external pressure of the end cover 4 is removed; the high-pressure nitrogen in the outer cavity 21 expands, restores the volume, and generates elastic force; it pushes the pull rod 3 to retract upward. During the retraction process of the pull rod 3, the pull rod 3 will cooperate with the steel ball 6 to drive the new cutting knife 100 to move upward; in this process, a part of the steel ball 6 will re-jam the neck 101 of the cutting knife 100, so that the cutting knife 100 will not fall from the knife placement chamber 25, thereby clamping the cutting knife 100 again and realizing the replacement of the cutting knife 100.

[0056] To sum up, the tool changing spindle of this embodiment provides a strong elastic force through the compression and expansion of high-pressure nitrogen, which quickly pushes the pull rod 3 to move, thereby realizing the rapid replacement of the cutting knife 100, greatly shortening the tool changing time, and improving the working efficiency of the equipment; at the same time, through the above structural design, the tool changing spindle of this embodiment is smaller in size, so that the tool changing spindle can be adapted to equipment with limited space.

[0057] See also Figure 6 Another embodiment of the present application further provides a tool changing device, comprising the tool changing spindle and hydraulic drive device 7 in the above-mentioned embodiment. The hydraulic drive device 7 comprises a cylinder 71 and a piston rod 72. The piston rod 72 is sleeved within the cylinder 71. The outer wall of the piston rod 72 and the inner wall of the cylinder 71 form an oil chamber 711. The cylinder 71 is provided with an oil inlet 712. Hydraulic oil is injected into the oil chamber 711 through an external oil pipe. In the working state, the hydraulic oil in the oil chamber 711 generates oil pressure to drive the piston rod 72 downward, causing the piston rod 72 to abut against the end cover 4, thereby driving the pull rod 3 downward. That is, the hydraulic drive device 7 provides the external pressure in the above-mentioned embodiment.

[0058] The above is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the claims of the present invention.

Claims

1. A tool changing spindle with built-in nitrogen, characterized in that: include: shell; an inner shell rotatably connected to the outer shell, wherein an outer cavity is provided in the inner shell, and high-pressure nitrogen is configured in the outer cavity; A pull rod is disposed in the inner shell and is used to clamp the cutting blade to enable replacement of the cutting blade; The end cover is sleeved on the inner shell and can slide relative to the inner shell under the action of external force. When the end cover moves downward, the end cover abuts against the pull rod and pushes the pull rod to move.

2. The tool changing spindle with built-in nitrogen according to claim 1, characterized in that: The outer cavity is formed by the space between the inner wall of the inner shell and the outer wall of the pull rod. The pull rod is provided with an inner cavity, and the inner cavity and the outer cavity are communicated.

3. The tool changing spindle with built-in nitrogen according to claim 2, characterized in that: A valve seat is also provided inside the pull rod, and an air valve is installed on the valve seat. The air nozzle of the air valve is placed in the inner cavity. The air valve injects high-pressure nitrogen into the inner cavity through an external air source. A channel is provided between the inner cavity and the outer cavity to enable high-pressure nitrogen to enter the outer cavity from the inner cavity.

4. The tool changing spindle with built-in nitrogen according to claim 1, characterized in that: It also includes a plurality of steel balls. A plurality of ball holes are correspondingly provided at one end of the pull rod. Each of the ball holes is used to cooperate with the steel ball to achieve the clamping and separation of the pull rod from the cutting knife.

5. The tool changing spindle with built-in nitrogen according to claim 3, characterized in that: First sealing rings are provided at both ends of the outer cavity, and sealing covers are installed at both ends of the pull rod.

6. The tool changing spindle with built-in nitrogen according to claim 1, characterized in that: It also includes a coupling, which is fixedly connected to the inner shell, and a spring is provided between the coupling and the end cover.

7. The tool changing spindle with built-in nitrogen according to claim 1, characterized in that: A first limiting block is provided between the inner shell and the pull rod, and the first limiting block is engaged with the inner wall of the inner shell; a second limiting block is provided inside the inner shell, and the second limiting block is fixedly connected to the inner shell or formed integrally therewith.

8. The tool changing spindle with built-in nitrogen according to claim 3, characterized in that: The inner shell is provided with a knife-holding chamber for accommodating a cutting knife; a ball-rolling cavity is provided in the knife-holding chamber.

9. The tool changing spindle with built-in nitrogen according to claim 8, characterized in that: A second sealing ring is provided between the inner shell and the pull rod, and the second sealing ring is located above the knife-setting chamber; a third sealing ring is provided between the valve seat and the pull rod.

10. A tool changing device, characterized in that: It comprises a tool changing spindle and a hydraulic drive device with built-in nitrogen as described in any one of claims 1 to 9, wherein the hydraulic drive device comprises a cylinder body and a piston rod, wherein the piston rod is sleeved in the cylinder body, the outer wall of the piston rod and the inner wall of the cylinder body form an oil chamber, and the cylinder body is provided with an oil inlet hole, and hydraulic oil is injected into the oil chamber through an external oil pipe. In the working state, the hydraulic oil in the oil chamber generates oil pressure to drive the piston rod to move downward, so that the piston rod and the end cover abut against each other, thereby driving the pull rod to move downward.

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