A polishing method for a vascular stent

Abstract

The present application provides a polishing method for a vascular stent, comprising assembling a vascular stent to be polished on a polishing tool, wherein the polishing tool comprises a tool body arranged in a spiral shape, and a first connecting portion and a second connecting portion connected to both ends of the tool body, wherein the vascular stent can be sleeved outside the tool body, and electrochemical polishing is performed by alternately and repeatedly energizing both ends of the polishing tool until the vascular stent meets the polishing requirements. The present application adopts a double-sided clamping intermittent electrolysis method, combined with the coordination mode of the polishing tool and the vascular stent, so that the distribution of current in the vascular stent is significantly improved, and the polishing effect is particularly prominent, which is particularly suitable for slender vascular stents.

Description

Technical Field

[0001] The present application relates to the field of medical devices, and in particular to a polishing method for a vascular stent. Background Art

[0002] Medical metal stents mainly act on narrow tissue cavities or blood vessel cavities to help rebuild the blood flow channels in tissue cavities or blood vessel cavities and maintain normal physiological functions of the human body. Traditional medical metal stents are usually cut by laser. There are generally slag, burrs and oxide layers on the surface of the metal stent after cutting, which must be post-processed. The post-processing usually includes grinding, sandblasting and electrochemical polishing. Since electrochemical polishing can not only reduce the surface roughness of the stent and improve the biocompatibility of the stent, but also improve the overall application performance of the metal stent, it is widely used in the post-processing of metal stents. Prior art CN207933554U discloses an electrochemical polishing tool for cardiovascular stents, which has a tool hole for accommodating a vascular stent formed inside the polishing tool. However, using this method, the contact point between the vascular stent and the polishing tool is difficult to ensure, and the polishing effect is not ideal. Summary of the invention

[0003] In view of this, the present application provides a polishing method for a vascular stent, which adopts the method of externalizing the vascular stent to a polishing body and combining a double-sided intermittent power supply method, so that the current distribution during the electrolysis process is uniform and the polishing effect is significant.

[0004] The present application provides a method for electrochemical polishing of a vascular stent, comprising:

[0005] Assembling the vascular stent to be polished on a polishing tool, wherein the polishing tool comprises a tool body arranged in a spiral shape, and a first connecting portion and a second connecting portion connected to two ends of the tool body, and the vascular stent can be sleeved outside the tool body;

[0006] The blood vessel stent is completely immersed in the polishing liquid, and a cathode connected to the negative electrode of the power supply is also provided in the polishing liquid. At the same time, only one of the first connecting part and the second connecting part is connected to the positive electrode of the power supply;

[0007] Step A: the first connection portion is connected to the positive electrode of the power supply, the cathode and the first connection portion form a current loop, and the vascular stent is subjected to a first electrochemical polishing under set electrochemical polishing parameters;

[0008] Step B: the second connection portion is connected to the positive electrode of the power supply, the cathode and the second connection portion form a current loop, and the stent is subjected to a second electrochemical polishing under set electrochemical polishing parameters;

[0009] Repeat step A and step B alternately until the polishing times reach the preset value.

[0010] Furthermore, it also includes a first connecting plate and a second connecting plate connected to the positive pole of the power supply, the first connecting portion is connected to the first connecting plate, and the second connecting portion is connected to the second connecting plate.

[0011] Furthermore, the outer diameter D1 of the tool body is greater than the inner diameter D2 of the vascular stent.

[0012] Furthermore, the outer diameter D1 of the tool body and the inner diameter D2 of the vascular stent satisfy the following relationship: (D1-D2)≥ 0.5mm~1mm.

[0013] Furthermore, the inner diameter of the vascular stent can be expanded by 40% to 80% by the tooling body.

[0014] Furthermore, the polishing liquid is flowing, and the polishing liquid is a mixed solution of perchloric acid, methanol and n-butanol, and the flow rate of the polishing liquid at the vascular stent is 0.1m / s~0.26m / s.

[0015] Furthermore, the electrochemical polishing parameters include a polishing voltage U and a polishing current I. During the entire polishing process, the polishing voltage U satisfies 10V≤U≤15V;

[0016] The polishing current I satisfies 1A≤I≤5A.

[0017] Furthermore, the electrochemical polishing parameters also include a single polishing time T. During the entire polishing process, the single polishing time T remains unchanged and satisfies 10s≤T≤30s.

[0018] Furthermore, the outer diameter D1 of the tool body satisfies 1.5 mm≤D1≤2.5 mm, and the length L of the tool body satisfies 100 mm≤L≤250 mm.

[0019] Furthermore, the connecting portion is arranged parallel to the axial direction of the tooling body.

[0020] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0021] The present application only energizes one end of the polishing tool at the same time. By alternately replacing the energized end of the polishing tool and combining the coordination between the polishing tool and the vascular stent, the current distribution during the polishing process is significantly improved, and the polishing effect is particularly outstanding. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an embodiment of the polishing tool of the present application;

[0023] Figure 2It is a schematic diagram of the polishing process of the polishing tool of the present application;

[0024] Figure 3 This is the data diagram of the rib width comparison between double-side clamping and single clamping in the comparative experiment (1);

[0025] Figure 4 This is a comparison data chart of the rib thickness between double-sided clamping and single clamping in comparative experiment (1).

[0026] Reference numerals:

[0027] 100. Polishing tool; 11. Tool body; 12. Connection part; 200. Polishing equipment; 21. Upper connection plate; 211. Upper connection plate terminal; 22. Lower connection plate; 221. Lower connection plate terminal; 23. Cathode; 231. Cathode terminal. DETAILED DESCRIPTION

[0028] The specific implementation of the present application will be described in detail below with reference to the accompanying drawings.

[0029] Vascular stents are medical devices used in vascular lesions to prop open blood vessels for blood circulation. With the development of the medical field, there are more and more types of vascular stents, which also brings challenges to the manufacturing of vascular stents. Polishing is an important part of vascular stent manufacturing. Electrochemical polishing is widely used in the polishing of vascular stents due to its unique advantages. At present, the mainstream methods of electrochemical polishing of vascular stents include single-point clamping method and single-point hanging method. Among them, the single-point clamping method uses a clamping device (such as tweezers) to clamp the end of the vascular stent to be polished to polish the vascular stent. The single-point hanging method uses a polishing tool with a tooling hole inside to load the vascular stent for polishing, and the vascular stent is placed in the tooling hole. However, with the development of vascular stent types, vascular stents with relatively long lengths and relatively small inner diameters have appeared. Since the vascular stent is composed of metal wires, as the length increases and the inner diameter decreases, the resistance of the entire vascular stent will also increase, and the existing polishing methods are difficult to apply. For the single-point clamping method, the current can only be conducted downward from the clamping point, but due to the large resistance of the vascular stent, it is difficult for the current to be conducted to the end, resulting in uneven polishing. Although the single-point hanging method can increase the contact points for current to pass through, the contact area is limited and the contact is unstable. For vascular stents with longer lengths and smaller inner diameters, the polishing effect is still not ideal. At present, there are basically no manufacturers in China that can handle such products, and they can only be polished by foreign companies. The polishing method provided by this application makes up for this technical gap very well, greatly reducing production costs and production cycles.

[0030] like Figure 1As shown, the present application discloses a polishing tool 100, which includes a tool body 11 arranged in a spiral shape, and connecting parts 12 connected to both ends of the tool body 11, which are respectively a first connecting part and a second connecting part. The vascular stent to be polished is sleeved on the outside of the polishing tool 100. In this embodiment, the outer diameter D1 of the tool body 11 is greater than the inner diameter D2 of the vascular stent to be polished, so that the vascular stent to be polished can be sleeved on the outside of the tool body 11. The vascular stent usually has an extreme contraction state and an extreme expansion state, and the two states correspond to the minimum inner diameter and the maximum inner diameter, respectively. Therefore, it is necessary to explain that, unless otherwise specified, the inner diameter D2 of the vascular stent described in the present application is the inner diameter of the vascular stent in the natural state. At this time, the inner diameter D2 of the vascular stent is between the minimum inner diameter and the maximum inner diameter, and can be contracted or expanded within a certain range.

[0031] In this embodiment, the outer diameter of the spiral coil of the tool body 11 remains consistent. When the vascular stent is placed outside the tool body 11, it can ensure that there are enough and evenly distributed contact points between the tool body 11 and the vascular stent.

[0032] With the single-point hanging method of the prior art, the metal wires that make up the vascular stent will cause adjacent metal wires to contact each other due to contraction, and the polishing liquid will have difficulty infiltrating this area, resulting in a polishing dead angle. However, the present application sets the vascular stent on the outside of the polishing tool 100, and expands the vascular stent, which not only increases the distance between the metal wires, but also avoids the contact between adjacent metal wires. At the same time, in this state, the distance between adjacent metal wires becomes farther, and it also provides bubbles with enough escape space, so that the bubbles generated by electrolysis can be released in time. If the bubbles generated during the polishing process cannot be released into the polishing liquid in time, the bubbles will adhere to the surface of the vascular stent, preventing the surface of the vascular stent from contacting the polishing liquid. After polishing, pitting will occur in the bubble area, affecting the surface quality of the vascular stent.

[0033] In order to set the vascular stent on the outside of the polishing tool 100, the assembly problem of the two needs to be considered, that is, how to put the smaller vascular stent on the larger polishing tool 100. If there is no suitable assembly method, the solution of external vascular stent cannot be implemented. For this reason, the applicant uses the retractable performance of the vascular stent. During the assembly process, the vascular stent to be polished is first expanded, and a stainless steel cylinder with an inner diameter larger than the outer diameter of the tool body 11 is placed in the vascular stent to be polished, and then the tool body 11 is loaded into the inner cavity of the stainless steel cylinder, and finally the stainless steel cylinder is pulled out to complete the assembly. This assembly is suitable for vascular stents with shape memory effect and superelastic effect, such as nickel-titanium alloy vascular stents. However, each material has its expansion limit. Considering the expansion requirements during the assembly process, the expansion degree of the vascular stent after assembly is not the greater the better. Once the expansion amount of the vascular stent exceeds the maximum expansion amount, it cannot be contracted. Therefore, it is preferred that the inner diameter D2 of the vascular stent is expanded by 40% to 80% by the tooling body 11 compared to the natural state. At this time, the vascular stent can fully contact with the polishing liquid and can also meet the assembly requirements.

[0034] Preferably, the flow rate of the polishing liquid can be adjusted based on the structure of the polishing tool 100 to control the mass transfer of electrolytes at an appropriate rate to improve the polishing effect. The polishing process is a process of electrolyte consumption. Once the electrolytes on the surface of the stent are consumed and cannot be replenished in time, the local electrolyte concentration will change, which will lead to uneven polishing of the stent. Therefore, the polishing liquid needs to be in a flowing state. When the inner diameter D2 of the stent is expanded by 40% to 80% by the tool body 11 compared to the natural state, the flow rate of the polishing liquid at the stent is controlled at 0.1m / s to 0.26m / s, and the mass transfer rate of the electrolyte can better meet the electrolysis requirements under this contact area, and the stent resistance generated by the flow rate is also relatively controllable.

[0035] In order to ensure that the tool body 11 and the blood vessel stent to be polished are in firm contact during the electrochemical process and to meet the size requirements of both during assembly, it is preferred that the outer diameter D1 of the tool body 11 and the inner diameter D2 of the blood vessel stent to be polished satisfy the following relationship:

[0036] (D1-D2) ≥0.5mm~1mm

[0037] At this time, the vascular stent and the polishing tool 100 can meet the assembly requirements, and the vascular stent can also be firmly attached to the tool body 11, and there is no risk of the vascular stent falling due to the small difference in size between the two.

[0038] Compared with the prior art, the present application innovatively sets the tooling body 11 on the inner side of the vascular stent, greatly increasing the contact area between the vascular stent and the tooling body 11, and effectively saving polishing time and current. The mainstream single-point hanging method, although simple in structure and easy to operate, requires the outer diameter of the vascular stent to be smaller than the inner diameter of the tooling hole in order to allow the vascular stent to enter the tooling hole. Once the outer diameter of the vascular stent is smaller than the inner diameter of the tooling hole, there will be a gap between the two, and it will be difficult to ensure sufficient contact between the vascular stent and the polishing tooling, resulting in insufficient contact area between the two, and the polishing effect of the vascular stent is relatively poor. For electrochemical polishing, the contact area and uniformity between the vascular stent and the polishing tooling 100 will not only affect the quality of polishing, but also directly affect the time and current required for the polishing process. If the contact area between the two is large and uniform, the electrolysis process can be evenly distributed on the surface of the vascular stent, the higher the polishing efficiency, and the shorter the required polishing time. In addition, the uniform current distribution is also less likely to cause local excessive electrolysis and current waste.

[0039] The two ends of the tooling body 11 are also provided with connecting parts 12, and the tooling body 11 and the connecting parts 12 are made of the same size, and the cross-sectional diameter is preferably 0.2mm~0.5mm, including the end value. The connecting part 12 is preferably linear and arranged parallel to the axial direction of the tooling body 11, so that when installing or removing the vascular stent, the vascular stent can be inserted into and withdrawn from the tooling body 11 from the connecting part 12. Especially during disassembly, because the vascular stent is arranged on the outside of the tooling body 11, the outer diameter of the tooling body 11 can be reduced by stretching the connecting parts 12 at both ends, so that the vascular stent can be smoothly moved out of the tooling body 11. In the single-point hanging method, the size of the tooling hole is larger than the size of the vascular stent, so it is more convenient to disassemble, so its connecting part is usually only provided with one end for connecting the positive pole of the power supply.

[0040] In this embodiment, the connecting portion 12 is not only used to connect the positive pole of the power supply, but also provides a force point required for stretching. Therefore, it is required to have a certain length. Preferably, the length of the connecting portion 12 is greater than or equal to 10 mm and less than or equal to 30 mm, that is, it will not cause material waste due to being too long and will not have no effect due to being too short.

[0041] The tool body 11 and the connecting part 12 of the polishing tool 100 can be made of the same material or different materials. For ease of processing, the same material is preferably used, such as titanium wire, nickel-titanium alloy wire, and stainless steel wire. When made of the same material, the tool body 11 and the connecting part 12 can be processed from one piece of the above material.

[0042] Preferably, the pitch of the tool body 11 is greater than or equal to 2 mm and less than or equal to 5 mm. The denser the pitch, the more contact points there are between the tool body 11 and the vascular stent, the larger the contact area, and the better the polishing effect. However, once the pitch is too dense, it is easy to cause the bubbles generated during the polishing process to not diffuse in time, thereby causing the polishing effect to deteriorate. In view of this, according to the assembly structure of the polishing tool 100 and the vascular stent of the present application, it is preferred to set the pitch of the tool body 11 to 2 mm~5 mm to maximize the polishing effect of the polishing tool of the present application. And when disassembling the vascular stent, it is relatively simple to stretch the tool body 11.

[0043] Preferably, the outer diameter D1 of the tool body 11 satisfies 1.5mm≤D1≤2.5mm, and the length L of the tool body 11 satisfies 100mm≤L≤250mm. This size design is suitable for a vascular stent with a length of 100mm~250mm and an inner diameter of 1.2mm~1.5mm. Such a vascular stent has a large resistance and is difficult to polish using existing technology, or the polishing effect is poor and it is difficult to meet the polishing requirements.

[0044] The present application also discloses a polishing method for a vascular stent. The polishing method is combined with the polishing tool 100 as described above and is suitable for polishing a vascular stent. Figure 2 As shown, the polishing device 200 used in the present application is independently provided with a first connecting plate and a second connecting plate that can be connected to the positive electrode of the power supply on both the upper and lower surfaces, and can be respectively provided with an upper connecting plate 21 and a lower connecting plate 22 according to the position. The upper and lower connecting plates 21 and 22 exist as the connection medium between the polishing tool 100 and the positive electrode of the power supply. Multiple polishing tools 100 can be arranged on the connecting plate to achieve one-time processing of multiple vascular stents. In some embodiments, the connecting plate may not be included, and the positive electrode of the power supply is directly connected to the first connecting part and the second connecting part. A cathode 23 connected to the negative electrode of the power supply is provided on the side of the polishing device 200, and the cathode 23 can be designed to be cylindrical. When the cathode 23 is set to be cylindrical and the polishing tool 100 is set at the center of the cylinder, it can be ensured that the distance from the polishing tool 100 to the cathode 23 in all directions is consistent, avoiding the occurrence of potential difference. The polishing device 200 is filled with polishing liquid, which is in contact with the cathode. At the same time during the electrochemical polishing process, the cathode 23 forms a current loop with only one of the upper connecting plate 21 and the lower connecting plate 22.

[0045] Before polishing, the vascular stent to be polished needs to be assembled on the polishing tool 100. As mentioned above, the vascular stent to be polished can be expanded to the outside of a stainless steel cylinder, and then the polishing tool 100 is inserted into the stainless steel cylinder and finally the stainless steel cylinder is pulled out.

[0046] After assembly, the polishing tool 100 is placed in the polishing liquid. In order to improve the mass transfer effect, the polishing liquid is flowing. The connecting parts 12 at both ends of the polishing tool 100, the first connecting part and the second connecting part are respectively connected to the upper connecting plate 21 and the lower connecting plate 22. At this time, although the connecting parts 12 are connected to the upper and lower connecting plates 21 and 22, the terminals 211 and 221 of the upper and lower connecting plates 21 and 22 are not connected to the power supply, and the electrochemical process has not yet been carried out. During the electrolytic polishing process, it is necessary to control the connection and disconnection of the upper and lower connecting plate terminals 211 and 221 with the positive pole of the power supply by a control switch or other means. When polishing is required through the upper connecting plate 21, the upper connecting plate 21 is connected to the positive pole of the power supply; when polishing is required through the lower connecting plate 22, the lower connecting plate 22 is connected to the positive pole of the power supply. For the polishing method adopted in the present application, at the same time of polishing, only one connecting plate is connected to the positive pole of the power supply, that is, at the same time, either the upper connecting plate 21 is turned on and the lower connecting plate 22 is disconnected, or the lower connecting plate 22 is turned on and the upper connecting plate 21 is disconnected.

[0047] Then, step A is started: the upper connecting plate terminal 211 is connected to the positive electrode of the power supply, the cathode terminal 231 is connected to the negative electrode of the power supply, and the polishing tool 100 is electrochemically polished for the first time according to the set electrochemical polishing parameters. Among them, the electrochemical polishing parameters include polishing voltage U, polishing current I and single polishing time T. Single polishing time T is the time of single continuous power-on of the upper connecting plate or the lower connecting plate each time. Taking the first electrochemical polishing as an example, the single polishing time T is the power-on time of the upper connecting plate in the first electrochemical polishing.

[0048] Preferably, the polishing voltage U satisfies 10V≤U≤15V; the polishing current I satisfies 1A≤I≤5A. The electrochemical polishing current and polishing voltage are affected by the limiting diffusion current, wherein the diffusion current refers to the current generated by the diffusion of ions from the polishing liquid to the electrode for electrode reaction, and in the present application, it refers to the current generated by the diffusion of electrolytes to the polishing tool 100. The maximum value of the diffusion current is the limiting diffusion current. The magnitude of the diffusion current is affected by the diffusion rate of the electrolyte. Therefore, when the flow rate of the polishing liquid at the vascular stent is 0.1m / s~0.26m / s, the polishing current I and the polishing voltage U are set to 1A≤I≤5A and 10V≤U≤15V, respectively, which are relatively appropriate. Once the polishing current I or the polishing voltage U is too low, it is easy to cause pitting on the surface of the vascular stent, and if it is too high, it is easy to cause over-polishing.

[0049] Preferably, the single polishing time T satisfies 10s≤T≤30s. The single polishing time T is affected by the polishing liquid. In some embodiments, the polishing liquid selects a mixed solution of perchloric acid, methanol, and n-butanol. Since perchloric acid has strong oxidizing properties, a suitable electrochemical polishing time is required. Once the time is too long, excessive corrosion of the vascular stent is likely to occur. If the time is too short, the complexity of the polishing process will increase. At the same time, the single polishing time T is also affected by the polishing current I and the polishing voltage U. When the polishing current I satisfies 1A≤I≤5A and the polishing voltage U satisfies 10V≤U≤15V, selecting a single polishing time T of 10s≤T≤30s can be greatly suitable for the use of perchloric acid, methanol, and n-butanol polishing liquid systems. At the same time, in order to maintain the consistency of the removal amount at the upper and lower ends, it is preferred that the single polishing time remains unchanged.

[0050] Then, step B is performed, the connection between the upper connecting plate terminal 211 and the positive electrode of the power supply is disconnected, and the lower connecting plate terminal 221 is connected to the positive electrode of the power supply, the connection mode of the cathode 23 remains unchanged, and the polishing tool 100 is subjected to secondary electrochemical polishing according to the set electrochemical polishing parameters. It should be noted that the electrochemical parameter settings for the first electrochemical polishing, the second electrochemical polishing, and even the subsequent multiple electrochemical polishings can be the same or different. The electrochemical parameters include polishing voltage U, polishing current I, and single polishing time T. When uniform electrochemical parameters are used throughout the polishing process, the operation process can be simplified. When the single polishing time T of each polishing is consistent, the removal amount of the vascular stent can be guaranteed to be consistent during each polishing, thereby ensuring the stability of the removal amount of the vascular stent during the polishing process. Of course, the electrochemical parameter settings can also be adjusted according to the burr situation of the vascular stent.

[0051] Afterwards, the connection between the upper connecting plate terminal 211 and the lower connecting plate terminal 221 and the positive pole of the power supply is continuously and alternately changed. During the process, the connection mode of the cathode 23 remains unchanged, and electrochemical polishing is performed under the set electrochemical parameters until the number of polishings reaches the preset value. That is, steps A and B are continuously and alternately repeated until the number of polishings reaches the preset value. The preset value here is pre-set, and the set value can be determined by a preliminary experiment or can be estimated. Generally, before batch processing of vascular stents, the same batch of vascular stents will be pre-experimented under the same conditions, and the measurement will require several polishing processes for the vascular stents to meet the size and surface quality requirements. The size and surface quality of the vascular stent are measured by a microscope, and the surface quality measurement includes whether there are burrs, pits, pits and other poor appearance.

[0052] After polishing is completed, the polishing tool 100 and the stent are removed from the polishing device 200, and the polishing tool 100 in the stent is removed to obtain a finished stent. The stent can be removed by stretching the connecting parts 12 at both ends of the polishing tool 100. Stretching the connecting parts 12 at both ends causes the tool body 11 in the middle part to deform under force, thereby reducing the diameter. When its outer diameter is reduced to less than the inner diameter of the stent, the stent can be easily removed from the tool body 11.

[0053] The present application designs the polishing tool 100 as a structure with connecting parts 12 at both ends. On the one hand, it is particularly suitable for the electrochemical polishing method proposed in the present application. The two ends of the connecting part 12 can be used to connect two connecting plates at different positions. Compared with the polishing tool with a connecting part only on one side, it is more convenient to have connecting parts on both sides during use, and the connection with the connecting plate is more stable. In some embodiments, a protruding hook structure can be provided on the lower connecting plate 22. Before electrochemical polishing, the connecting part 12 at the bottom of the polishing tool 100 can be appropriately bent so that the connecting part 12 at the bottom is hung and connected with the lower connecting plate 22 to achieve the function of conductivity. After polishing is completed, the connection between the upper connecting plate 21 and the polishing tool 100 is first released, and then the position of the polishing tool 100 and the lower connecting plate 22 are adjusted to release the connection between the polishing tool 100 and the lower connecting plate 22.

[0054] The bottom of the polishing tool in the prior art is usually a chassis with a bottom support. If it is applied to the polishing method of the present application, the spiral chassis at the bottom is difficult to clamp due to the structure itself, so it is difficult to apply to the polishing method proposed in the present application. On the other hand, the polishing tool 100 disclosed in the present application is particularly convenient in the process of withdrawing the vascular stent because it has connecting parts 12 on both sides. The connecting part 12 provides a good force point, so that the tool body 11 can be deformed to a sufficient extent by simply stretching the connecting part 12, thereby removing the vascular stent.

[0055] The present application abandons the traditional thinking and sets the vascular stent tightly on the outer surface of the polishing tool 100, which greatly increases the contact area between the vascular stent and the polishing tool 100, and improves the current distribution. On this basis, the present application also creatively adopts intermittent power supply on both sides to replace the traditional single-sided clamping for electrochemical polishing, avoiding the complicated polishing process, and at the same time, the uniformity of the current during the polishing process is further improved compared with the single-sided continuous power supply. The material on the surface of the vascular stent can be evenly removed during the electrochemical polishing process, avoiding the problem of uneven local size of the vascular stent, and filling the technical gap.

[0056] In comparative experiment (1), two groups of vascular stents with an outer diameter of 1.3 mm and a length of 100 mm were subjected to comparative experiments under the same electrochemical parameters (polishing voltage of 12 V, polishing current of 1.5 A, single polishing time of 20 s) and the same polishing liquid. The dimensions of the vascular stent before polishing were rib width 0.12 ± 0.01 mm and rib thickness 0.13 ± 0.01 mm (rib width is the cross-sectional width of the metal wire constituting the vascular stent, and rib thickness is its cross-sectional thickness). The dimensions of the vascular stent after polishing were required to be rib width 0.08 ± 0.01 mm and rib thickness 0.09 ± 0.01 mm. In comparative experiment (1), the two groups of test points were evenly distributed in the axial direction of the vascular stent and in the same position. The dimensions of the double-sided clamped polishing tooling were tooling main body length 100 mm and outer diameter 1.6 mm. The vascular stent was sheathed on the outside of the tooling main body, and then polished by intermittent power supply at both ends, with a single polishing time of 20 s. The single clamping scheme uses tweezers to directly clamp the vascular stent. After one side is powered on, the direction of the vascular stent is turned and the next polishing is performed. The above process is repeated alternately until the polishing is completed. The single polishing time for each end is 20s. The size data of the vascular stent after polishing is shown in Table 1 and Table 2:

[0057] Table 1 Double-side clamping test data

[0058]

[0059] Table 2 Single-side clamping test data

[0060]

[0061] According to Table 1, Table 2 and Figure 3 and Figure 4 As shown, the standard deviation of rib width and rib thickness using the double-sided clamping method proposed in the present application is significantly lower than that of the traditional single-sided clamping method, and the surface polishing of the vascular stent is more uniform.

[0062] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A polishing method for a vascular stent, characterized in that: include, Assemble the vascular stent to be polished on a polishing tool, wherein the polishing tool comprises a tool body arranged in a spiral shape, and a first connecting portion and a second connecting portion connected to two ends of the tool body, the vascular stent can be sleeved outside the tool body, and the outer diameter D1 of the tool body is greater than the inner diameter D2 of the vascular stent; The blood vessel stent is completely immersed in the polishing liquid, a cathode connected to the negative electrode of the power supply is also provided in the polishing liquid, the first connecting part is connected to the positive electrode of the power supply through the first connecting plate, and the second connecting part is connected to the positive electrode of the power supply through the second connecting plate. At the same time, only one of the first connecting part and the second connecting part is connected to the positive electrode of the power supply; Step A: the first connection portion is connected to the positive electrode of the power supply, the cathode and the first connection portion form a current loop, and the vascular stent is subjected to a first electrochemical polishing under set electrochemical polishing parameters; Step B: the second connection portion is connected to the positive electrode of the power supply, the cathode and the second connection portion form a current loop, and the stent is subjected to a second electrochemical polishing under set electrochemical polishing parameters; Repeat step A and step B alternately until the polishing times reach the preset value.

2. The polishing method according to claim 1, characterized in that: The outer diameter D1 of the tool body and the inner diameter D2 of the vascular stent satisfy the following relationship: (D1-D2)≥ 0.5mm~1mm.

3. The polishing method according to claim 1, characterized in that: The inner diameter of the vascular stent can be expanded by 40% to 80% by the tooling body.

4. The polishing method according to claim 3, characterized in that: The polishing liquid is flowing, and is a mixed solution of perchloric acid, methanol and n-butanol. The flow rate of the polishing liquid at the vascular stent is 0.1m / s~0.26m / s.

5. The polishing method according to claim 1, characterized in that: The electrochemical polishing parameters include polishing voltage U and polishing current I. During the whole polishing process, the polishing voltage U satisfies 10V≤U≤15V; The polishing current I satisfies 1A≤I≤5A.

6. The polishing method according to claim 5, characterized in that: The electrochemical polishing parameters also include a single polishing time T. During the entire polishing process, the single polishing time T remains unchanged and satisfies 10s≤T≤30s.

7. The polishing method according to claim 1, characterized in that: The outer diameter D1 of the tool body satisfies 1.5 mm≤D1≤2.5 mm, and the length L of the tool body satisfies 100 mm≤L≤250 mm.

8. The polishing method according to claim 1, characterized in that: The connecting portion is arranged parallel to the axial direction of the tooling body.

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