A solid phase extraction nitrogen blowing integrated device

Abstract

A solid phase extraction nitrogen blowing integrated device belongs to the technical field of sample preparation for testing, including: a platform, a disk is provided in the middle, four extraction tubes are arranged along the circumference of the disk, and solid phase extraction columns are arranged in the extraction tubes. A cleaning tube, a sample tube, a rinsing tube and a flushing tube are arranged in sequence along the circumference above the platform, and the disk is arranged to rotate around the axis; two nitrogen blowpipes are provided, and the two nitrogen blowpipes are respectively vertically arranged at the two ends of a rotating plate, and the rotating plate is arranged to rotate around the position between the two nitrogen blowpipes. The lower end of the nitrogen blowpipe is provided with a claw for grabbing the test tube; a turntable is arranged parallel to the bottom of the platform, and a plurality of mounting holes are arranged along the circumference of the turntable for inserting the test tube; the axis of the turntable is located at the midpoint of the line connecting the through hole and the axis of the flushing tube, and the turntable is arranged to rotate around the axis, and the distance between the mounting hole and the axis of the turntable is equal to the distance between the turntable and the axis of the through hole. This scheme can prepare samples automatically and continuously, and has a high sample preparation efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of test sample preparation, and in particular relates to a solid phase extraction nitrogen blowing integrated device. Background Art

[0002] Solid-Phase Extraction, referred to as SPE, is a sample pretreatment technology developed in recent years. It is developed by combining solid-phase extraction columns and liquid chromatography technology. It is mainly used for sample separation, purification and concentration. Compared with traditional liquid phase extraction, it can improve the recovery rate of analytes, more effectively separate analytes from interfering components, and reduce the sample pretreatment process. It is widely used in medicine, food, environment, chemical industry and other fields.

[0003] The general steps of solid phase extraction usually include: activation, using activation liquid to clean the extraction tube and the solid phase extraction column placed inside it, and the activation liquid is automatically discharged from the bottom of the extraction tube after use; adding samples, adding a predetermined amount of sample solution to the extraction tube, allowing the sample solution to flow through the solid phase extraction column, and the sample solution is discharged from the bottom of the extraction tube after flowing through the solid phase extraction column. After this process, the target will be adsorbed on the solid phase extraction column; elution, adding organic phase to the extraction tube to remove organic impurities on the solid phase extraction column, while the target remains in the solid phase extraction column, and the organic phase will be discharged from the bottom of the extraction tube; collection, flushing the solid phase extraction column with mobile phase, so that the target flows into the test tube from the bottom of the extraction tube; nitrogen blowing, using nitrogen to blow dry the liquid collected in the test tube, and the target will remain in the test tube, thereby obtaining the target sample. In traditional sample preparation, the above process is mainly completed manually, and in order to ensure the accuracy of the test results, multiple samples need to be prepared for verification. If the above sample preparation method is still used, it is not only time-consuming and labor-intensive, but also has low sample preparation efficiency. Summary of the invention

[0004] In order to solve the deficiencies of the prior art, the present invention provides a solid phase extraction nitrogen blowing integrated device, which can automatically and continuously prepare samples and has a high sample preparation efficiency.

[0005] In order to achieve the purpose of the present invention, the following scheme is proposed:

[0006] A solid phase extraction nitrogen blowing integrated device, comprising:

[0007] The platform has a disk in the middle, four extraction tubes are arranged in an array along the circumference of the disk, and solid phase extraction columns are arranged in the extraction tubes. The disk is coaxially provided with a through hole, and a cleaning tube, a sample loading tube, a leaching tube and a flushing tube are arranged in sequence along the circumference above the platform. The disk is rotatably arranged around the axis, and a waste liquid tube is arranged below the platform and is aligned with the cleaning tube, the sample loading tube and the leaching tube one by one.

[0008] Two nitrogen blowpipes are provided, and the two nitrogen blowpipes are respectively vertically arranged at both ends of a rotating plate, and the rotating plate is arranged to rotate around the middle position of the line connecting the two nitrogen blowpipes. The axis of rotation of the rotating plate and the two nitrogen blowpipes are perpendicular to the disc, and the nitrogen blowpipes are arranged to move along the axis direction. A plurality of claws are arranged on the outside of the lower end of the nitrogen blowpipe along the circumferential array for grabbing the test tube;

[0009] The turntable is arranged parallel to the bottom of the platform. A plurality of mounting holes are arranged along a circumferential array on the turntable for inserting test tubes. A plurality of avoidance grooves are opened along the circumference of the side walls of the mounting holes for passing the claws. The axis of the turntable is located at the midpoint of the line connecting the through hole and the axis of the flushing tube. The turntable is arranged to rotate around its own axis, and the distance between the mounting hole and the axis of the turntable is equal to the distance between the turntable and the axis of the through hole.

[0010] The beneficial effects of the present invention are: the present solution can continuously prepare samples, can effectively shorten the intermediate waiting time, improve the sample preparation efficiency, and can effectively save manpower. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention.

[0012] Figure 1 A schematic diagram of the top structure of the present application is shown.

[0013] Figure 2 Shows Figure 1 A partial enlarged view of point A in the middle.

[0014] Figure 3 A schematic diagram of the bottom structure of the present application is shown.

[0015] Figure 4 A top view of a preferred structure of the present application is shown.

[0016] Figure 5 A top view of the present application is shown.

[0017] Figure 6 A bottom view of the present application is shown.

[0018] Figure 7 A schematic diagram of the bottom structure of the lifting plate is shown.

[0019] Figure 8 Shown along Figure 5 Cross-sectional view along the BB direction.

[0020] Fig. 9 Shows Figure 8 A partial enlarged view of point C in the middle.

[0021] Fig.10 Shows Figure 8A partial enlarged view of point D in the middle.

[0022] Markings in the figure: platform-11, disc-12, through hole-121, cleaning tube-13, sample tube-14, elution tube-15, flushing tube-16, waste liquid tube-17, rotating motor-18, nut-19, nitrogen blowpipe-2, turntable-21, support rod-22, bracket-221, adjustment motor-23, rotating cylinder-24, claw-25, ring-251, cylindrical spring-252, drive motor-26, friction wheel-261, turntable-3, mounting hole-31, avoidance groove-311, lifting plate-4, lifting cylinder-41, turntable motor-42, extraction tube-91, retaining ring-911, test tube-92, pressure spring-93. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the implementation modes of the present invention are described in detail below with reference to the accompanying drawings. However, the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments.

[0024] like Figures 1 to 9 As shown, a solid phase extraction nitrogen blowing integrated device includes: a platform 11, a nitrogen blowing tube 2 and a turntable 3, etc.

[0025] Specifically, a disc 12 is provided in the middle of the platform 11, and four extraction tubes 91 are arranged in a circular array along the circumference of the disc 12. A solid phase extraction column is arranged in each of the extraction tubes 91. As a preferred arrangement structure, the top opening of the extraction tube 91 is flush with the top surface of the disc 12 or protrudes from the top surface of the disc 12. The disc 12 is coaxially provided with a through hole 121. A cleaning tube 13, a sample loading tube 14, a rinsing tube 15 and a flushing tube 16 are sequentially provided along the circumference above the platform 11. The disc 12 is rotatably arranged around an axis to align the top opening of the extraction tube 91 with the lower ports of the cleaning tube 13, the sample loading tube 14, the rinsing tube 15 and the flushing tube 16 in sequence. The alignment described here is axis alignment, which mainly aligns the top opening of the extraction tube 91 with the lower ports of the cleaning tube 13, the sample loading tube 14, the rinsing tube 15 and the flushing tube 16; a waste liquid tube 17 aligned one by one with the cleaning tube 13, the sample loading tube 14 and the rinsing tube 15 is provided below the platform 11.

[0026] Specifically, two nitrogen blowpipes 2 are provided, and the two nitrogen blowpipes 2 are respectively vertically inserted at the two ends of a rotating plate 21. The rotating plate 21 is arranged to rotate around the middle position of the line connecting the two nitrogen blowpipes 2, so as to make the nitrogen blowpipe 2 coaxial with the disc 12, that is, the nitrogen blowpipe 2 and the disc 12 can be made coaxial by rotating the rotating plate 21, and the axis of rotation is arranged at the middle position of the two nitrogen blowpipes 2. The axis of rotation of the rotating plate 21 and the two nitrogen blowpipes 2 are perpendicular to the disc 12, and the nitrogen blowpipe 2 is arranged to move along the axis direction, specifically, a cylinder is arranged on the rotating plate 21, so as to control the movement of the nitrogen blowpipe 2 along the axis, and a plurality of claws 25 are arranged on the outer side of the lower end of the nitrogen blowpipe 2 along the circumferential array, so as to coaxially grasp the outer edge of the upper end of the test tube 92.

[0027] As a specific installation structure, such as Figure 1 As shown, the rotating plate 21 is arranged on the top of a support rod 22, the support rod 22 is located above the disc 12, and the bottom of the support rod 22 is higher than the top surface of the extraction tube 91. A bracket 221 is provided on the top surface of the platform 11 for suspending the support rod 22 above the disc 12. An adjusting motor 23 is provided on the side of the support rod 22, and its main shaft is provided with a driving gear. The bottom surface of the rotating plate 21 is provided with a driven bevel gear meshing with the driving bevel gear, and the driven bevel gear is coaxially arranged with the rotating axis of the rotating plate 21. In this way, the adjusting motor 23 can be used to control the rotation of the rotating plate 21, thereby switching the positions of the two nitrogen blowpipes 2.

[0028] As another preferred structure, Figure 4 As shown, the rotating plate 21 is arranged on the rotating shaft of a rotating cylinder 24, and the rotating cylinder 24 is used to directly control the rotating angle and position of the rotating plate 21. The rotating cylinder 24 is arranged above the rotating plate 21, and the rotating cylinder 24 can be suspended by a bracket 221. The bracket 221 is a supporting part, and a suitable structural design can be selected according to the installation method of the support rod 22. Figure 1 and Figure 4 The two structures shown in the figure are not intended to limit their forms.

[0029] Specifically, the turntable 3 is arranged parallel to the lower part of the platform 11, and the turntable 3 is provided with a plurality of mounting holes 31 along a circumferential array for inserting the test tube 92, and the side wall of the mounting hole 31 is provided with a plurality of avoidance grooves 311 along a circumference for inserting the claw 25; the axis of the turntable 3 is located at the midpoint of the line connecting the through hole 121 and the axis of the flushing tube 16, the turntable 3 is arranged to rotate around its own axis, and the distance between the mounting hole 31 and the axis of the turntable 3 is equal to the distance between the axis of the turntable 3 and the through hole 121. Through the above structure, the mounting hole 31 can be aligned with the through hole 121 and the flushing tube 16 by rotating the turntable 3. Specifically, the rotating shaft of the turntable 3 can be installed at the bottom of the platform 11, and a motor is arranged on the platform 11 to drive the rotating shaft of the turntable 3 to rotate, or a mounting structure is arranged separately below the platform 11 to rotate and install the turntable 3.

[0030] The method of preparing the sample using the above scheme is as follows: by rotating the disc 12, the extraction tube 91 on the disc 12 is aligned with the cleaning tube 13, the sample tube 14, the rinsing tube 15 and the flushing tube 16 respectively; the activation liquid is injected into the extraction tube 91 below the cleaning tube 13, and the extraction tube 91 and the solid phase extraction column placed therein are cleaned with the activation liquid. After use, the activation liquid automatically flows from the bottom of the extraction tube 91 to the waste liquid tube 17 below and then is discharged; the disc 12 is rotated to move the cleaned extraction tube 91 to the bottom of the sample tube 14, and a predetermined amount of sample solution is added into the extraction tube 91 through the sample tube 14, so that the sample solution flows through the solid phase extraction column, and the target object is adsorbed on the solid phase extraction column. , after the sample solution flows through the solid phase extraction column, it is discharged from the bottom of the extraction tube 91 and flows into the waste liquid pipe 17 below and then discharged. The extraction tube 91 originally located below the flushing tube 16 will also be moved to the bottom of the cleaning tube 13 and cleaned; the disc 12 is rotated again to move the extraction tube 91 that has completed the sample loading process to the bottom of the elution tube 15, and the organic phase is added into the extraction tube 91 through the elution tube 15 to remove the organic impurities on the solid phase extraction column, while the target object remains in the solid phase extraction column. The organic phase will be discharged from the bottom of the extraction tube 91 and flows into the waste liquid pipe 17 below and then discharged; the disc 12 is continued to be rotated to move the extraction tube 91 that has completed the elution and impurity removal to the bottom of the flushing tube 16. At this time, the target object is still retained in the solid phase extraction column. The organic phase will be discharged from the bottom of the extraction tube 91 and flows into the waste liquid pipe 17 below and then discharged. By rotating the turntable 3, one of the test tubes 92 is aligned coaxially with the flushing tube 16, and then the mobile phase can be added to the extraction tube 91 below through the flushing tube 16, and the solid phase extraction column is flushed with the mobile phase, so that the target object flows from the bottom of the extraction tube into the test tube 92 below; the turntable 3 is rotated to move the test tube with the target object collected to the bottom of the through hole 121, and the rotating plate 21 is rotated to align one of the nitrogen blowpipes 2 with the through hole 121, and the nitrogen blowpipe 2 aligned with the through hole 121 is moved downward, and the outer edge of the upper end of the test tube 92 is clamped by the claw 25 under the nitrogen blowpipe 2 through the avoidance groove 311, and then nitrogen can be blown into the test tube 92 through the nitrogen blowpipe 2, and the liquid collected in the test tube 92 is blown away by the nitrogen blowpipe 2. Blow dry; the extraction tube 91 at the rear will also be cleaned, loaded, rinsed and nitrogen blown in sequence; as a preferred method, after the claw 25 clamps the test tube 92, the test tube 92 is pulled out from the turntable 3 by the nitrogen blow tube 2, and then a new test tube 92 is placed in the vacant mounting hole 31 of the turntable 3, and then the rotating plate 21 is rotated to remove the test tube 92 in the nitrogen blowing process from above the through hole 121, so as to facilitate another nitrogen blow tube 2 to nitrogen blow and transfer the subsequent test tube 92. The removed test tube 92 continues to perform nitrogen blowing during the rising and rotating process, which can effectively utilize the time during the transfer process to speed up the nitrogen blowing process. After the nitrogen blowing is completed, the test tube 92 can be directly pulled downward from the claw 25. Through the above scheme, samples can be made continuously, the waiting time in the middle can be effectively shortened, the sample preparation efficiency can be improved, and manpower can be effectively saved.During specific use, the solid phase extraction column can be replaced, while the extraction tube 91, as a common container for the solid phase extraction column, does not need to be replaced, because after each extraction tube 91 completes a cycle of sample collection, it will participate in cleaning to prevent the sample from being interfered by the previous sample.

[0031] Preferably, Figure 1 , Figure 3 and Figures 6 to 8 As shown, a lifting plate 4 is provided in parallel below the platform 11, and is movable in a direction perpendicular to the platform 11. The waste liquid pipes 17 are all penetrated on the lifting plate 4. By moving the lifting plate 4 upward or downward, the cleaning pipe 13, the sample loading pipe 14 and the rinsing pipe 15 can be connected or separated from the corresponding waste liquid pipe 17, which can not only prevent the leakage of waste liquid, but also will not affect the rotation of the disc 12. The turntable 3 is rotatably arranged on the lifting plate 4 to control the connection and separation between the test tube 92 and the flushing pipe 16, so as to prevent liquid leakage and reduce the sample volume. At the same time, by moving the lifting plate 4 upward, the distance between the turntable 3 and the nitrogen blowpipe 2 can be shortened, thereby helping to reduce the moving stroke of the nitrogen blowpipe 2 and reduce the size of the device. structural dimensions; as a preferred solution, the lifting plate 4 is connected to the platform 11 through two lifting cylinders 41 arranged on both sides, so that the movement of the lifting plate 4 is controlled by the lifting cylinders 41. In addition to the lifting cylinders 41, a hydraulic cylinder or a linear motor can also be used to control the movement of the lifting plate 4; as a preferred solution, a turntable motor 42 is provided on the lifting plate 4, and its main shaft is provided with a gear, and the outside of the turntable 3 is provided with a tooth structure meshing with the gear, so that the turntable 3 can be driven to rotate by the turntable motor 42; this structure can also be used for driving the disc 12. Specifically, a rotating motor 18 is provided on the platform 11, a gear is provided on its main shaft, and teeth meshing with the gear are provided on the circumferential outer wall of the disc 12.

[0032] Further preferably, the lower end surfaces of the cleaning tube 13, the sample loading tube 14, the rinsing tube 15 and the flushing tube 16 are all provided with caps with an elastic structure. When the lifting plate 4 rises to a predetermined position, the cap is pressed against the top surface of the extraction tube 91 to close the top opening of the extraction tube 91 to prevent liquid from splashing out. The cap with an elastic structure can prevent the extraction tube 91 from being crushed, and can improve the stability of the extraction tube 91 and prevent the extraction tube 91 from shaking.

[0033] Preferably, Figure 1 As shown, the lower ends of all waste liquid pipes 17 are connected to the same main pipeline to facilitate unified collection of waste liquid.

[0034] Preferably, Figure 2 and Fig. 9As shown, the claws 25 on the same extraction tube 91 are all integrally formed at the lower end of a circular ring 251, and the circular ring 251 is sleeved on the outside of the extraction tube 91. Specifically, the circular ring 251 is connected to the extraction tube 91 by screw locking or welding. The lower end of the extraction tube 91 is lower than the bottom surface of the claw 25, and the outer diameter of the extraction tube 91 is smaller than the inner diameter of the test tube 92, so that the extraction tube 91 can be inserted into the test tube 92 to improve the nitrogen blowing effect. A cylindrical spring 252 is provided on the bottom surface of the circular ring 251. When the claw 25 clamps the test tube 92, the lower end of the cylindrical spring 252 is pressed against the top surface of the test tube 92, thereby improving the stability of the test tube 92 to prevent the test tube 92 from shaking during the process of clamping the test tube 92 and nitrogen blowing.

[0035] Preferably, Figure 1 and Figures 3 to 5 As shown, the two nitrogen blowpipes 2 corresponding to the top surface of the rotating plate 21 are both provided with a driving motor 26, and the main shafts thereof are both provided with a friction wheel 261. The friction wheels 261 of the two driving motors 26 are respectively in contact with the outer walls of the corresponding nitrogen blowpipes 2, and the axes of the friction wheels 261 are perpendicular to the corresponding nitrogen blowpipes 2, so that the friction wheels 261 can be driven to rotate by the driving motor 26, thereby driving the nitrogen blowpipes 2 in contact therewith to move along the axis through the friction wheels 261.

[0036] Further preferably, Figure 5 As shown, the circumferential outer wall of the friction wheel 261 is provided with an annular groove, and the outer wall of the extraction tube 91 cooperates with the annular groove to increase the contact area between the extraction tube 91 and the friction wheel 261 and increase the friction force.

[0037] Preferably, Fig.10 As shown, a retaining ring 911 is provided in the middle section of the outer wall of the extraction tube 91, and the upper end of the hole on the disc 12 for penetrating the extraction tube 91 is a countersunk structure, and a nut 19 of a circular ring structure is provided on the top of the countersunk hole. The outer wall of the nut 19 and the inner wall of the countersunk hole are threadedly connected, and the extraction tube 91 passes through the countersunk hole and the nut 19, and the retaining ring 911 is inserted into the countersunk hole. A pressure spring 93 is sleeved on the upper end of the extraction tube 91, which is pressed between the top surface of the retaining ring 911 and the bottom surface of the nut 19. Through the above-mentioned structural arrangement, the extraction tube 91 can be stably connected to the disc 12, to prevent the extraction tube 91 from shaking during the rotation of the disc 12, and to press the extraction tube 91 downward to ensure that the top and bottom positions of the extraction tube 91 remain constant without being affected by external forces, so as to facilitate the connection of the cleaning tube 13, the sample loading tube 14, the rinsing tube 15, the flushing tube 16 and the waste liquid tube 17. In addition, during the implementation process, the lifting plate 4 can also meet the requirement of pushing the extraction tube 91 upward, so that the top of the extraction tube 91 actively fits with the bottom of the cleaning tube 13, the sample loading tube 14, the rinsing tube 15 and the flushing tube 16.

[0038] The above description is only a preferred embodiment of the present invention, and is not intended to be the only one or to limit the present invention. Those skilled in the art should understand that various changes or equivalent substitutions made to the present invention without departing from the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A solid phase extraction nitrogen blowing integrated device, characterized in that: include: A platform (11) is provided with a disk (12) in the middle thereof, four extraction tubes (91) are arranged in a circular array along the circumference of the disk (12), each of the extraction tubes (91) is provided with a solid phase extraction column, a through hole (121) is coaxially opened on the disk (12), a cleaning tube (13), a sample loading tube (14), a rinsing tube (15) and a flushing tube (16) are arranged in sequence along the circumference above the platform (11), the disk (12) is rotatably arranged around the axis, and a waste liquid tube (17) is provided below the platform (11) and is aligned one by one with the cleaning tube (13), the sample loading tube (14) and the rinsing tube (15); Two nitrogen blowpipes (2) are provided and are respectively vertically inserted through two ends of a rotating plate (21). The rotating plate (21) is rotatably arranged around the middle position of the line connecting the two nitrogen blowpipes (2). The rotating axis of the rotating plate (21) and the two nitrogen blowpipes (2) are perpendicular to the disc (12). The nitrogen blowpipes (2) are movable along the axis direction. A plurality of claws (25) are arranged along the circumference of the outer portion of the lower end of the nitrogen blowpipe (2) for grabbing the test tube (92). A turntable (3) is arranged parallel to the bottom of the platform (11), and the turntable (3) is provided with a plurality of mounting holes (31) in a circumferential array for inserting the test tube (92), and a plurality of avoidance grooves (311) are opened along the circumference of the side wall of the mounting hole (31) for inserting the claw (25); the axis of the turntable (3) is located at the midpoint of the line connecting the through hole (121) and the axis of the flushing tube (16), the turntable (3) is arranged to rotate around its own axis, and the distance between the mounting hole (31) and the axis of the turntable (3) is equal to the distance between the axis of the turntable (3) and the through hole (121); A lifting plate (4) is provided parallel to the lower side of the platform (11) and is arranged to move in a direction perpendicular to the platform (11). The waste liquid pipes (17) are all arranged on the lifting plate (4). The turntable (3) is rotatably arranged on the lifting plate (4). The claws (25) on the same extraction tube (91) are all integrally formed at the lower end of a circular ring (251). The circular ring (251) is sleeved on the outside of the extraction tube (91). The lower end of the extraction tube (91) is lower than the bottom surface of the claws (25), and the outer diameter of the extraction tube (91) is smaller than the inner diameter of the test tube (92). A cylindrical spring (252) is provided on the bottom surface of the circular ring (251). When the claws (25) clamp the test tube (92), the lower end of the cylindrical spring (252) is pressed against the top surface of the test tube (92).

2. A solid phase extraction nitrogen blowing integrated device according to claim 1, characterized in that: The lower end surfaces of the cleaning tube (13), the sample loading tube (14), the elution tube (15) and the flushing tube (16) are all provided with caps of an elastic structure, and when the lifting plate (4) rises to a predetermined position, the caps are pressed tightly against the top surface of the extraction tube (91).

3. A solid phase extraction nitrogen blowing integrated device according to claim 1, characterized in that: The lower ends of all waste liquid pipes (17) are connected to the same main pipeline.

4. A solid phase extraction nitrogen blowing integrated device according to claim 1, characterized in that: The top surface of the rotating plate (21) is provided with driving motors (26) corresponding to the two nitrogen blowing pipes (2), and the main shafts of the driving motors (26) are provided with friction wheels (261). The friction wheels (261) of the two driving motors (26) are respectively in contact with the outer walls of the corresponding nitrogen blowing pipes (2), and the axes of the friction wheels (261) are perpendicular to the corresponding nitrogen blowing pipes (2).

5. A solid phase extraction nitrogen blowing integrated device according to claim 4, characterized in that: An annular groove is provided on the circumferential outer wall of the friction wheel (261), and the outer wall of the extraction tube (91) cooperates with the annular groove.

6. The solid phase extraction nitrogen blowing integrated device according to claim 1, characterized in that: A retaining ring (911) is provided in the middle section of the outer wall of the extraction tube (91); the upper end of the hole on the disc (12) for inserting the extraction tube (91) is a countersunk structure; a nut (19) of a circular ring structure is provided at the top of the countersunk hole; the outer wall of the nut (19) and the inner wall of the countersunk hole are threadedly connected; the extraction tube (91) passes through the countersunk hole and the nut (19); the retaining ring (911) is inserted into the countersunk hole; a pressure spring (93) is sleeved on the upper end of the extraction tube (91) and is pressed between the top surface of the retaining ring (911) and the bottom surface of the nut (19).

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