A polishing device and method for the inner wall of a metal variable diameter sampling needle.

Abstract

This application relates to the technical field of electrochemical polishing, and in particular to a polishing device and method for the inner wall of a metal variable-diameter sampling needle. The polishing device includes an electrolyte tank, a power supply, a cathode metal rod, an insulating capillary, and an electrolyte circulation mechanism. By inserting the insulating capillary into the variable-diameter section of the sampling needle, and through electrolyte circulation and electrochemical reaction, polishing is achieved on the outlet area of ​​the insulating capillary, thereby effectively polishing the inner wall of the metal variable-diameter sampling needle. This method has the advantages of simple operation, good polishing effect, and wide applicability, effectively solving the problem that traditional methods are difficult to use for polishing the inner wall of variable-diameter sampling needles.

Description

Technical Field

[0001] This application relates to the technical field of electrochemical polishing, and in particular to a polishing device and polishing method for the inner wall of a metal variable diameter sampling needle. Background Technology

[0002] A sampling needle is a tool specifically designed for the precise collection of samples and is widely used in fields such as medicine, bioscience, chemical analysis, and industrial testing. It can be categorized into various types based on its intended use, such as sampling needles for medical instruments, used for sampling bodily fluids or tissues, etc.

[0003] In practical applications, for certain special scenarios, variable-diameter sampling needles are designed. One end of the variable-diameter sampling needle has a larger inner diameter, while the other end has a smaller inner diameter, typically less than 0.3 mm. The manufacturing method for this type of sampling needle generally involves using a standard constant-diameter sampling needle, narrowing one end. However, after machining, burrs are present at the diameter-reduction point due to the compression during processing. These burrs can negatively impact the normal use of the sampling needle; therefore, polishing is necessary to remove them.

[0004] Currently, the main methods for polishing the inner wall of sampling needles include electrochemical polishing, magnetic abrasive polishing, and abrasive flow polishing. However, due to the small diameter of the diameter-changing section of the sampling needle, abrasive polishing easily clogs the needle. Traditional electrochemical polishing electrodes also cannot penetrate deeply into the small diameter of the sampling needle and remain stable, making it difficult to polish the diameter-changing section.

[0005] Therefore, how to polish the inner wall of the variable diameter section of the variable diameter sampling needle is a technical problem that needs to be solved. Summary of the Invention

[0006] This application provides a polishing device and polishing method for the inner wall of a metal variable diameter sampling needle, in order to solve the problem that the inner wall of a variable diameter sampling needle is difficult to polish.

[0007] Firstly, the polishing device for the inner wall of a metal variable diameter sampling needle provided in this application adopts the following technical solution:

[0008] A polishing device for the inner wall of a metal variable diameter sampling needle includes an electrolyte tank, a power supply, a cathode metal rod, an insulating capillary tube, and an electrolyte circulation mechanism.

[0009] The cathode metal rod is connected to the negative terminal of the power supply and is placed inside the electrolyte tank. The cathode metal rod is located outside the variable diameter sampling needle. The anode of the power supply is used to connect to the surface of the variable diameter sampling needle.

[0010] One end of the insulating capillary extends into the electrolyte tank, and the other end is inserted into the variable diameter sampling needle. The electrolyte circulation mechanism includes a peristaltic pump. The inlet of the peristaltic pump is connected to the variable diameter sampling needle through a pipe, and the outlet is connected to the electrolyte tank through a pipe.

[0011] By adopting the above technical solution, the insulating capillary is inserted into the larger diameter end of the inner hole of the variable diameter sampling needle until its outlet position reaches the variable diameter position. Since the inner hole of the variable diameter sampling needle is too small, the resistance of the electrolyte inside it is greater than the resistance of the variable diameter sampling needle. The current preferentially passes through the variable diameter sampling needle. Therefore, the current only passes through the initial contact position between the electrolyte and the variable diameter sampling needle, which is the outlet position of the insulating capillary. Thus, the area of ​​the outlet of the insulating capillary is the polishing area, thereby achieving polishing of the inner wall of the variable diameter sampling needle at the variable diameter position.

[0012] Preferably, it further includes a fixing mechanism, the fixing mechanism including a conduit, the capillary extending into the interior of the conduit, a fixing joint being provided inside the conduit, and the insulating capillary being fixedly connected to the fixing joint.

[0013] By adopting the above technical solution, the variable diameter sampling needle can be inserted into the conduit, thereby achieving the fixation and protection of the variable diameter sampling needle. The fixing joint fixes the insulating capillary, which helps to connect the insulating capillary with the variable diameter sampling needle.

[0014] Preferably, the conduit is made of transparent material, and the fixing mechanism further includes a positioning guide sleeve fixedly disposed inside the conduit. The positioning guide sleeve is made of metal and connected to the positive terminal of the power supply. The insulating capillary is coaxially disposed with the positioning guide sleeve, and the end of the insulating capillary is located inside the positioning guide sleeve.

[0015] By adopting the above technical solution, the positioning guide sleeve can guide and position the variable diameter sampling needle, making it easier to connect the variable diameter sampling needle to the insulating capillary and improving the ease of operation.

[0016] Preferably, the positioning guide sleeve includes a conical positioning ring and a conductive spring coil. The positioning ring is connected to the inner wall of the conduit. A through groove is formed on the circumference of the positioning ring. The conductive spring coil is wrapped around the positioning ring and located in the through groove. The conductive spring coil is connected to the anode of the power supply.

[0017] By adopting the above technical solution, the positioning ring can guide the variable diameter sampling needle, and the conductive spring coil can abut against the side wall of the variable diameter sampling needle. The conductive spring coil is connected to the positive anode of the power supply through a wire, thereby connecting the variable diameter sampling needle to the power supply.

[0018] Preferably, both ends of the positioning guide sleeve are provided with fixing claws, the fixing claws include multiple elastic fixing pieces, the ends of the elastic fixing pieces are provided with locking blocks, and the inner wall of the guide tube is provided with positioning grooves that cooperate with the locking blocks.

[0019] By adopting the above technical solution, the fixing claw enables the connection between the positioning ring and the conduit. Multiple positioning grooves can be provided along the axial direction of the conduit, and the position of the positioning guide sleeve in the conduit can be adjusted by changing the cooperation between the locking block and different positioning grooves, thus making it more widely applicable.

[0020] Preferably, the fixing joint is made of rubber, and the insulating capillary passes through the center of the fixing joint; an installation groove is provided on the end face of the fixing joint, the installation groove surrounds the insulating capillary, and the installation groove is inserted and cooperated with the variable diameter sampling needle to seal the end of the variable diameter sampling needle.

[0021] By adopting the above technical solution, the fixed joint can connect the insulated capillary to the guide tube and improve the stability of the insulated capillary. Simultaneously, the mounting groove and the variable diameter sampling needle are fitted together to seal the end of the variable diameter sampling needle.

[0022] Preferably, it also includes a suction connector, which includes a connecting pipe connected to the inlet of the peristaltic pump via a pipeline. The suction connector also includes a fixing pipe, which is disposed inside the fixing pipe and is detachably connected to the conduit.

[0023] By adopting the above technical solution, the suction connector can greatly facilitate the connection between the peristaltic pump and the variable diameter sampling needle. The connecting tube can connect the variable diameter sampling needle to the peristaltic pump, while the fixed tube and the conduit are connected to form a whole, thereby protecting the variable diameter sampling needle.

[0024] Preferably, the end of the insulating capillary is further provided with a guide head, which includes a central rod, a guide rod and a contact rod. One end of the central rod extends into the inner wall of the insulating capillary, and the other end is located outside the insulating capillary.

[0025] The contact rod is located around the center rod and abuts against the inner wall of the insulating capillary, thereby fixing the center rod and the insulating capillary relative to each other. The guide rod is located at the end of the center rod outside the insulating capillary and is inclined relative to the center rod.

[0026] By adopting the above technical solution, the contact rod abuts against the inner wall of the insulating capillary, thereby fixing the central rod and the insulating capillary relative to each other. The guide rod is located outside the insulating capillary and can play a guiding role, so that the insulating capillary can be accurately inserted into the interior of the variable diameter sampling needle.

[0027] On the other hand, this application provides a polishing method for the inner wall of a metal variable diameter sampling needle based on the above-mentioned metal variable diameter sampling needle inner wall polishing device, comprising the following steps:

[0028] Insert the insulating capillary into the variable diameter sampling needle from the end with the larger inner diameter. The outlet position of the insulating capillary determines the polishing position of the inner wall. After determining the polishing position, seal the connection between the insulating capillary and the variable diameter sampling needle.

[0029] The negative terminal of the DC power supply is connected to the cathode metal rod and placed in the electrolyte tank, while the anode is connected to the outer wall of the variable diameter sampling needle. The inlet of the insulating capillary is immersed in the electrolyte, and the variable diameter sampling needle does not contact the electrolyte. The outlet of the peristaltic pump is placed in the electrolyte tank, and the inlet is connected to the end of the variable diameter sampling needle with the smaller inner diameter and sealed.

[0030] Turn on the peristaltic pump to circulate the electrolyte inside the variable diameter sampling needle, adjust the polishing voltage and current, turn on the DC power supply, and polishing is completed after a certain period of time.

[0031] By adopting the above technical solution, since the inner hole of the variable diameter sampling needle is too small, the resistance of the electrolyte inside it is greater than the resistance of the variable diameter sampling needle. The current preferentially passes through the variable diameter sampling needle. Therefore, the current only passes through the initial contact position between the electrolyte and the variable diameter sampling needle, that is, the outlet position of the insulating capillary, thereby polishing the inner wall of the variable diameter part of the variable diameter sampling needle.

[0032] In summary, the present invention has at least one of the following beneficial technical effects:

[0033] 1. Insert the insulating capillary tube into the end with the larger inner diameter of the variable diameter sampling needle until its outlet reaches the variable diameter position. Because the inner diameter of the variable diameter sampling needle is too small, the resistance of the electrolyte inside is greater than the resistance of the variable diameter sampling needle. The current preferentially passes through the variable diameter sampling needle. Therefore, the current only passes through the initial contact position between the electrolyte and the variable diameter sampling needle, which is the outlet position of the insulating capillary tube. Therefore, the area at the outlet of the insulating capillary tube is the polishing area, thereby polishing the inner wall of the variable diameter sampling needle at the variable diameter position.

[0034] 2. The fixing mechanism in this application can fix the variable diameter sampling needle and accurately connect the variable diameter sampling needle to the insulating capillary, thereby reducing the operational difficulty of polishing work, reducing working costs, and facilitating the rapid promotion of the technology.

[0035] 3. The positioning guide sleeve enables the variable diameter sampling needle to be accurately connected to the insulating capillary tube. In addition, it can also connect the variable diameter sampling needle to the power supply through the connection of the conductive spring ring, which greatly improves the operating efficiency and facilitates the smooth progress of polishing work. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall structure of the polishing device for the inner wall of the metal variable diameter sampling needle in the embodiments of this application;

[0037] Figure 2 This is a cross-sectional view of the fixing mechanism in the embodiments of this application;

[0038] Figure 3 yes Figure 2 A magnified view of part A in the middle;

[0039] Figure 4 It is a structural schematic diagram used to show the relative positional relationship of the insulating capillary, guide head, positioning guide sleeve and conduit.

[0040] The attached diagram is labeled as follows: 1. Electrolyte tank; 2. Power supply; 3. Cathode metal rod; 4. Insulating capillary tube; 5. Electrolyte circulation mechanism; 6. Fixing mechanism; 61. Conduit; 62. Positioning guide sleeve; 621. Positioning ring; 622. Fixing claw; 623. Conductive spring coil; 63. Suction connector; 631. Connecting tube; 632. Fixing tube; 64. Fixing connector; 7. Guide head; 71. Center rod; 72. Guide rod; 73. Contact rod; 8. Variable diameter sampling needle; 81. Variable diameter position. Detailed Implementation

[0041] The following is in conjunction with the appendix Figure 1-4 The present invention will be described in further detail below.

[0042] This embodiment discloses a polishing device for the inner wall of a metal variable diameter sampling needle, referring to... Figure 1 The system includes components such as an electrolyte tank 1, a power supply 2, a cathode metal rod 3, an insulating capillary tube 4, and an electrolyte circulation mechanism 5. Specifically, the electrolyte tank 1 contains electrolyte, and the power supply 2 is placed on one side of the electrolyte tank 1. The cathode metal rod 3 is connected to the negative terminal of the power supply 2 and is placed inside the electrolyte tank 1, while the positive terminal of the power supply 2 is the anode and is connected to the surface of the variable diameter sampling needle 8. The variable diameter sampling needle 8 is specifically located on the outside of the electrolyte tank 1, avoiding direct contact between the variable diameter sampling needle 8 and the electrolyte. One end of the insulating capillary tube 4 extends into the electrolyte tank 1, and the other end is inserted into the interior of the variable diameter sampling needle 8 through the larger end of the variable diameter sampling needle 8. The electrolyte circulation mechanism 5 mainly consists of a peristaltic pump. The inlet of the peristaltic pump is connected to the smaller end of the variable diameter sampling needle 8 through a pipe, while the outlet is connected to the electrolyte tank 1 through a pipe.

[0043] In the specific implementation process, firstly, the insulating capillary tube 4 is inserted into the end with the larger inner diameter of the variable diameter sampling needle 8 until its outlet position reaches the variable diameter position 81. Then, the interface position is sealed to ensure that the electrolyte does not leak. Next, the cathode metal rod 3 is connected to the negative terminal of the power supply 2 and placed in the electrolyte tank 1; at the same time, the anode of the power supply 2 is connected to the outer wall of the variable diameter sampling needle 8. The peristaltic pump is started, and the peristaltic pump draws the electrolyte from the electrolyte tank 1 and delivers it to the interior of the variable diameter sampling needle 8 through the pipeline.

[0044] In this application, the area at the outlet of the insulating capillary 4 is the polishing area. Therefore, as long as the outlet of the insulating capillary 4 is located at the diameter change position 81, the diameter change position 81 can be polished, and other positions of the diameter change sampling needle 8 will not be polished.

[0045] The technical principle for achieving the above technical effects is as follows: because the inner hole of the variable diameter sampling needle 8 is too small, the resistance of the electrolyte inside it is greater than the resistance of the variable diameter sampling needle 8. The current preferentially passes through the variable diameter sampling needle 8. Therefore, the current only passes through the initial contact position between the electrolyte and the variable diameter sampling needle 8, that is, the outlet position of the insulating capillary 4.

[0046] The electrolyte circulates inside the variable diameter sampling needle 8 and polishes the inner wall of the variable diameter position 81 under the action of electrochemical reaction.

[0047] Reference Figure 2 and Figure 3 Furthermore, in this application, in order to fix the variable diameter sampling needle 8, the polishing device for the inner wall of the variable diameter sampling needle 8 also includes a fixing mechanism 6. The fixing mechanism 6 includes a suction connector 63, a guide tube 61, and a positioning guide sleeve 62 disposed inside the guide tube 61.

[0048] Specifically, the suction connector 63 includes a connecting tube 631 and a fixing tube 632. The connecting tube 631 is disposed inside the fixing tube 632 and the two are fixedly connected. One end of the connecting tube 631 passes through the fixing tube 632 and is connected to the inlet of the peristaltic pump, while the other end is placed inside the fixing tube 632. The diameter of the connecting tube 631 is slightly larger than the diameter of the small end of the reducing sampling needle 8, so that the small end of the reducing sampling needle 8 can be inserted into the connecting tube 631, thereby allowing the small end of the reducing sampling needle 8 to be connected to the peristaltic pump.

[0049] The end of the connecting tube 631 is flared and corresponds to the shape of the diameter change position 81 of the diameter change sampling needle 8, so that the connecting tube 631 can cover the outside of the diameter change position 81.

[0050] The connecting tube 631 is made of a rigid material to protect the reducing sampling needle 8. An elastic anti-slip layer is provided on the inner wall of the connecting tube 631, which abuts against the side wall of the reducing sampling needle 8, ensuring the reducing sampling needle 8 is stably placed in the connecting tube 631 and preventing it from falling out. The elastic anti-slip layer also seals the connection between the connecting tube 631 and the reducing sampling needle 8.

[0051] During implementation, first insert the small end of the variable diameter sampling needle 8 into the connecting tube 631 and connect it to the connecting tube 631. Then, hold the fixed tube 632 and insert the large end of the variable diameter sampling needle 8 into the conduit 61.

[0052] In this embodiment, the conduit 61 is specifically configured as a transparent plastic tube. The positioning guide sleeve 62 includes a positioning ring 621 coaxially arranged with the conduit 61, one end of which is tapered. To connect the positioning ring 621 to the conduit 61, both ends of the positioning ring 621 are provided with fixing claws 622. The fixing claws 622 include multiple elastic fixing pieces, the ends of which are provided with locking blocks. The inner wall of the conduit 61 is provided with positioning grooves that cooperate with the locking blocks. The insulating capillary 4 is coaxially arranged with the positioning ring 621, and the end of the insulating capillary 4 is located inside the positioning ring 621. Therefore, when the variable diameter sampling needle 8 is inserted into the conduit 61, the positioning ring 621 can guide the variable diameter sampling needle 8.

[0053] Reference Figure 3 and Figure 4 In order to accurately insert the end of the insulating capillary tube 4 into the variable diameter sampling needle 8, a guide head 7 is also provided at the end of the insulating capillary tube 4. The guide head 7 includes a central rod 71, a guide rod 72 and a contact rod 73. One end of the central rod 71 extends into the inner wall of the insulating capillary tube 4, and the other end is located outside the insulating capillary tube 4.

[0054] The contact rod 73 is located inside the insulating capillary tube 4 and is positioned around the central rod 71. The contact rod 73 abuts against the inner wall of the insulating capillary tube 4, thereby fixing the central rod 71 and the insulating capillary tube 4 relatively. The guide rod 72 is arranged in a cross shape at the end of the central rod 71 located outside the insulating capillary tube 4, and the guide rod 72 is inclined relative to the central rod 71. The guide rod 72 serves to guide the insertion of the insulating capillary tube 4 accurately into the variable diameter sampling needle 8.

[0055] The positioning guide sleeve 62 also includes a conductive spring coil 623, which is wound around the periphery of the positioning ring 621. A through groove is formed on the periphery of the positioning ring 621. The conductive spring coil 623, wrapped around the positioning ring 621, protrudes through the through groove to the inner side of the positioning ring 621, allowing it to abut against the side wall of the variable diameter sampling needle 8. The conductive spring coil 623 is connected to the positive anode of the power supply 2 via a wire, thereby connecting the variable diameter sampling needle 8 to the power supply 2.

[0056] Reference Figure 2 Furthermore, to improve the stability of the insulating capillary 4 by connecting it to the conduit 61, a fixing joint is provided inside the conduit 61. The fixing joint is made of rubber, and the insulating capillary 4 passes through the center of the fixing joint. An installation groove is provided on the end face of the fixing joint, which surrounds the insulating capillary 4. The installation groove is inserted and engaged with the variable diameter sampling needle 8 to seal the end of the variable diameter sampling needle 8.

[0057] The implementation principle of the polishing device for the inner wall of the metal variable diameter sampling needle in this embodiment is as follows: First, connect the small end of the variable diameter sampling needle 8 to the connecting tube 631. Then, hold the fixing tube 632 and insert the large end of the variable diameter sampling needle 8 into the conduit 61, and insert the insulating capillary 4 into the inside of the variable diameter sampling needle 8, so that the end of the insulating capillary 4 is located at the variable diameter position 81 of the variable diameter sampling needle 8. After connecting the cathode metal rod 3 to the negative terminal of the power supply 2, place it in the electrolyte tank 1, and connect the conductive spring coil 623 to the positive terminal of the power supply 2.

[0058] Driven by the peristaltic pump, the electrolyte enters the variable diameter sampling needle 8 and first contacts the variable diameter position 81, thereby polishing the variable diameter position 81.

[0059] Based on the above-mentioned polishing device for the inner wall of the metal variable diameter sampling needle, this application embodiment also discloses a polishing method for the metal variable diameter sampling needle, which adopts the following steps:

[0060] The insulating capillary tube 4 is inserted into the variable diameter sampling needle 8 from the end with the larger inner diameter. The outlet position of the insulating capillary tube 4 determines the polishing position of the inner wall. After determining the polishing position, the connection between the insulating capillary tube 4 and the variable diameter sampling needle 8 is sealed.

[0061] The negative terminal of DC power supply 2 is connected to the cathode metal rod 3 and placed in the electrolyte tank, while the anode is connected to the outer wall of the variable diameter sampling needle. The inlet of the insulating capillary tube 4 is immersed in the electrolyte, and the variable diameter sampling needle 8 does not contact the electrolyte. The outlet of the peristaltic pump is placed in the electrolyte tank, and the inlet is connected to the end of the variable diameter sampling needle 8 with the smaller inner diameter, and sealed with sealant.

[0062] Turn on the peristaltic pump to circulate the electrolyte inside the variable diameter sampling needle 8, adjust the polishing voltage and current, turn on the DC power supply 2, and polishing is completed after a certain period of time.

[0063] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A polishing device for the inner wall of a metal variable-diameter sampling needle, characterized by: It comprises an electrolyte tank (1), a power supply (2), a cathode metal rod (3), an insulating capillary tube (4) and an electrolyte circulating mechanism (5). The cathode metal rod (3) is connected with the negative pole of the power supply (2) and is arranged in the electrolyte tank (1), and the cathode metal rod (3) is located outside the variable-diameter sampling needle (8); the positive pole of the power supply (2) is used for being connected with the surface of the variable-diameter sampling needle (8). One end of the insulating capillary tube (4) extends into the electrolyte tank (1), and the other end is inserted into the variable-diameter sampling needle (8); the electrolyte circulating mechanism (5) comprises a peristaltic pump, the water inlet of the peristaltic pump is connected with the variable-diameter sampling needle (8) through a pipeline, and the water outlet is communicated with the electrolyte tank (1) through a pipeline. When polishing, the variable-diameter sampling needle (8) is arranged outside the electrolyte tank (1) to avoid direct contact between the variable-diameter sampling needle (8) and the electrolyte.

2. The apparatus of claim 1, wherein: It also comprises a fixing mechanism (6), the fixing mechanism (6) comprises a catheter (61), the capillary tube extends into the catheter (61), a fixed joint (64) is arranged in the catheter (61), and the insulating capillary tube (4) is fixedly connected with the fixed joint (64).

3. The apparatus of claim 2, wherein: The catheter (61) is made of transparent material, the fixing mechanism (6) further comprises a positioning guide sleeve (62) fixedly arranged in the catheter (61), the positioning guide sleeve (62) is made of metal and is connected with the positive pole of the power supply (2), the insulating capillary tube (4) is coaxially arranged with the positioning guide sleeve (62), and the end of the insulating capillary tube (4) is located inside the positioning guide sleeve (62).

4. The apparatus of claim 3, wherein: The positioning guide sleeve (62) comprises a conical cylinder positioning ring (621) and a conductive spring ring (623), the positioning ring (621) is connected with the inner wall of the catheter (61), a through groove is formed in the side of the positioning ring (621), the conductive spring ring (623) is arranged on the positioning ring (621) and located in the through groove, and the conductive spring ring (623) is connected with the positive pole of the power supply (2).

5. The apparatus of claim 4, wherein: Both ends of the positioning guide sleeve (62) are provided with fixed claws (622), the fixed claws (622) comprise a plurality of elastic fixing pieces, the end of the elastic fixing piece is provided with a clamping block, and a positioning groove matched with the clamping block is arranged on the inner wall of the catheter (61).

6. The apparatus of claim 4, wherein: The fixed joint (64) is made of rubber material, the insulating capillary tube (4) passes through the center of the fixed joint (64); an installation groove is formed in the end face of the fixed joint (64), the installation groove surrounds the insulating capillary tube (4), and the installation groove is in plug-in cooperation with the variable-diameter sampling needle (8) to seal the end of the variable-diameter sampling needle (8).

7. The apparatus of claim 2, wherein: The fixing mechanism (6) further comprises a suction joint (63), the suction joint (63) comprises a connecting pipe (631), the connecting pipe (631) is connected with the water inlet of the peristaltic pump through a pipeline, the suction joint (63) further comprises a fixing pipe (632), the connecting pipe (631) is arranged in the fixing pipe (632), and the fixing pipe (632) is detachably connected with the catheter (61).

8. The apparatus of claim 1, wherein: The end of the insulation capillary (4) is also provided with a guide head (7), the guide head (7) comprises a center rod (71), a guide rod (72) and a contact rod (73), one end of the center rod (71) extends into the inner wall of the insulation capillary (4), and the other end is located outside the insulation capillary (4); The contact rod (73) is arranged on the side of the center rod (71), the contact rod (73) abuts against the inner wall of the insulation capillary (4), so that the center rod (71) is relatively fixed with the insulation capillary (4); the guide rod (72) is arranged at one end of the center rod (71) located outside the insulation capillary (4), and the guide rod (72) is relatively inclined with the center rod (71).

9. A polishing method of a metal variable-diameter sampling needle based on a polishing device of an inner wall of the metal variable-diameter sampling needle according to claim 1, characterized by, The method comprises the following steps: The insulation capillary (4) is inserted into the inside of the variable-diameter sampling needle (8) from the end with a larger inner hole diameter, the outlet position of the insulation capillary (4) determines the polishing position of the inner wall, after the polishing position is determined, the connection part between the insulation capillary (4) and the variable-diameter sampling needle (8) is sealed; The negative electrode of the direct current power supply (2) is connected with the cathode metal rod (3) and is put into the electrolyte tank (1), the anode is connected with the outer wall of the variable-diameter sampling needle (8); the inlet of the insulation capillary (4) is immersed in the electrolyte, and the variable-diameter sampling needle (8) is arranged outside the electrolyte tank (1); the water outlet of the peristaltic pump is put into the electrolyte tank (1), the water inlet is connected with the end with a smaller inner hole diameter of the variable-diameter sampling needle (8) and is sealed; The peristaltic pump is opened to make the electrolyte circulate in the variable-diameter sampling needle (8), the direct current power supply (2) is opened, and the polishing voltage and current are adjusted, and after a certain time, the polishing is completed.

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