Dissimilar alloy winding spring welding method for interventional therapy guide wire

Abstract

The invention belongs to the technical field of interventional medical instruments, and relates to a dissimilar alloy winding spring welding method for an interventional therapy guide wire. According to the method, a nickel-titanium alloy memory wire is used as a main body of the interventional therapy guide wire, a winding spring mounting part of the nickel-titanium alloy memory wire is ground to form a conical shape, then a stainless steel winding spring and a platinum alloy winding spring are sleeved on the winding spring mounting part, and finally a spiral welding flux, namely a spring-shaped welding flux, is embedded into a gap between the stainless steel winding spring and the platinum alloy winding spring, so that the interventional therapy guide wire is formed. Welding is conducted after the brazing filler metal and the winding spring are tightly matched, isolation gas is used for protection in the welding process, and welding is completed through a brazing method. The method can effectively solve the technical problems of small welding surface, low welding strength and easy cracking and brittle failure of the fine stainless steel winding spring and the platinum alloy winding spring, not only protects the superelasticity and memory of the nickel-titanium alloy core wire, but also can ensure the welding strength of the winding spring.

Description

Technical Field

[0001] This invention belongs to the field of interventional medical device technology and relates to a dissimilar alloy spring welding method for interventional treatment guidewires. Background Technology

[0002] Guidewires are used to percutaneously introduce catheters into blood vessels or other lumens within the body. They are also essential tools for assisting catheters in selectively entering small vascular branches or other lesion cavities, and for changing catheters during procedures. Common examples include guidewires used in coronary interventional procedures. Their main functions are to enter the coronary arteries or traverse tortuous, calcified, stenotic, or collateral circulation areas to reach the target location, establish a track for delivering balloons, stents, and microcatheters; use guidewire upgrade or downgrade techniques to open coronary artery occlusions; and pre-enter coronary artery branches for protection and landmark functions.

[0003] Ideally, a guidewire should possess excellent maneuverability in both pushing and twisting. Due to its small diameter, it should also be resistant to deformation after bending when passing through and pushing through tortuous blood vessels. Because of its thinness and length, the guidewire tip should be easily inserted into the blood vessel and pass through tortuous sections or narrow points. Since many small blood vessels have weak walls, the tiny guidewire must exhibit maximum flexibility and hyperelasticity to minimize friction with the vessel wall and the potential for damage. Nickel-titanium shape memory alloy (NiTi) wires effectively meet these requirements. To provide better tactile feedback, a stainless steel spring sheath is often designed around the NiTi wire. In addition to the stainless steel spring sheath, researchers have added a platinum alloy spring coil to the guidewire tip, connecting it to the stainless steel spring sheath, to ensure enhanced visibility and tracking.

[0004] Current research on guidewire welding mainly focuses on welding different alloy materials within the guidewire body. For example, patent document CN109664022A discloses an intravascular nickel-titanium alloy guidewire and its welding method. The intravascular nickel-titanium alloy guidewire includes a coaxially arranged nickel-titanium alloy wire and a stainless steel tube. The nickel-titanium alloy wire has a step that inserts into the stainless steel tube. The step and the stainless steel tube are welded together by multiple weld points, and these weld points are not on the same cross-section. This technical solution achieves the welding of nickel-titanium alloy and stainless steel without filler. The spiral arrangement of the weld points avoids continuous concentrated heating on the cross-section, preventing brittle fracture. Controlling the heat-affected zone during welding minimizes the heat impact on the nickel-titanium alloy, preventing damage to its hyperelasticity. Patent document CN105562867B discloses an intravascular nickel-titanium alloy guidewire, guidewire welding fixture, and guidewire welding method. The welding method for the intravascular nickel-titanium alloy guidewire employs argon gas isolation. A third type of solder, capable of being fused to both ends, is placed between the nickel-titanium alloy and stainless steel welding ends. A multi-point welding method combining extremely small fusion welding points with rotating welding points is used to achieve end welding between the nickel-titanium alloy and stainless steel. Simultaneously, under argon gas protection, the solder located between the nickel-titanium alloy wire end and the stainless steel wire end is primarily heated, rather than directly heating either the nickel-titanium alloy wire end or the stainless steel wire end. A fixture continuously rotates the wire for multi-point circumferential heating with a small laser spot, continuously welding to complete the end connection between the nickel-titanium alloy and stainless steel. The aforementioned patent document mainly focuses on welding stainless steel pipes to nickel-titanium alloy wires. Since the structure of stainless steel pipes differs from that of stainless steel spring sheaths, whether this technical solution can be used for welding stainless steel spring sheaths requires experimental verification.

[0005] Currently, domestic production of stainless steel and platinum alloy springs for guidewires is limited, and welding these springs remains a bottleneck in medical device manufacturing. Spring wire diameters are often quite small, and some manufacturers use flux to weld stainless steel and platinum alloy springs together. However, this often results in low weld strength, cracking, and brittle fracture due to the small weld area. Therefore, developing a method for welding dissimilar alloy springs is a pressing technical challenge. Summary of the Invention

[0006] Based on this, the purpose of this invention is to provide a method for welding dissimilar alloy springs for interventional guidewires. Using this method, stainless steel springs and platinum alloy springs are welded together, resulting in high weld strength and resistance to breakage. At the same time, the overall flexibility and visibility of the springs are preserved, which can meet the requirements of clinical use.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for welding dissimilar alloy springs for interventional therapy guidewires, comprising the following steps: S1, Core wire grinding: Take a nickel-titanium alloy memory wire as the main body of the interventional treatment guide wire; grind the spring mounting part of the nickel-titanium alloy memory wire into a conical shape; S2, Spring Installation: (1) Take a stainless steel spring as the first alloy spring, the stainless steel spring including a first sparse section and a first regular section; put the stainless steel spring on the spring installation part; (2) Take the first brazing spring and the second brazing spring respectively and rotate them on both sides of the pitch gap of the first sparse section on the spring installation part, so that the first brazing spring and the second brazing spring are respectively located on both sides of the pitch gap of the stainless steel spring; (3) Take a platinum alloy spring as the second alloy spring, the platinum alloy spring including a second sparse section and a second regular section; put the platinum alloy spring on the spring installation part, the second sparse section is installed in the gap between the first brazing spring and the second brazing spring, filling the pitch gap of the first sparse section; S3, Spring Welding: The first sparse section, the first brazing spring, the second brazing spring, and the second sparse section of the sample assembled in S2 are used as the welding area. The sample is first treated with brazing process, and then cooled, annealed, and post-treated to complete the welding of dissimilar alloy springs.

[0008] Furthermore, the wire diameter of the stainless steel coiled spring is R1, the wire diameter of the platinum alloy coiled spring is R2, the pitch of the first sparse section is H1, and the pitch of the second sparse section is H2, wherein R1=R2=0.03±0.001mm, and H1=H2=R1×4=R2×4.

[0009] Furthermore, the wire diameter of the first solder spring is R3, the wire diameter of the second solder spring is R4, the pitch of the first solder spring is H3, the pitch of the second solder spring is H4, and R1=R2=R3=R4, and H1=H2=H3=H4.

[0010] Furthermore, the length of the first sparse segment is L1, the length of the second sparse segment is L2, the length of the first solder spring is L3, and the length of the second solder spring is L4; wherein L1=L2=L3=L4.

[0011] Further, the inner diameter of the coil of the stainless steel spring is A1, the inner diameter of the coil of the platinum alloy spring is A2, the inner diameter of the coil of the first brazing spring is A3, and the inner diameter of the coil of the second brazing spring is A4, wherein A1=A2=A3=A4; the outer diameter of the coil of the stainless steel spring is B1, the outer diameter of the coil of the platinum alloy spring is B2, the outer diameter of the coil of the first brazing spring is B3, the outer diameter of the coil of the second brazing spring is B4, and the diameter of the nickel-titanium alloy memory wire is C, wherein B1=B2=B3=B4=C=0.3±0.01mm.

[0012] Furthermore, the maximum diameter of the conical spring mounting portion is D, where D < A1 or A2; the length of the conical spring mounting portion is L5, the length of the stainless steel spring is L6, and the length of the platinum alloy spring is L7, where L5 ≥ L6 + L7.

[0013] Furthermore, the pitch of both the first and second conventional sections is 0 mm, and the components of the first and second brazed springs include tin, silver, or copper.

[0014] Furthermore, the brazing process parameters are as follows: the sample is placed on a vacuum adsorption platform in an argon atmosphere, a negative pressure of -20kPa to -50kPa is used, and a laser preheating beam with a power of 1 to 2W is used to preheat the welding area to 100℃ to 150℃ for 10s to 20s; a picosecond pulsed laser is used for welding, with a power of 20w to 25w, a spot diameter ≤20μm, and a scanning speed ≤2mm / s.

[0015] Furthermore, the cooling annealing process parameters are as follows: the brazed sample is placed in a constant temperature chamber at 140℃~160℃ for annealing for ≥30 minutes.

[0016] Furthermore, the post-processing procedure involves grinding the welded area of ​​the welded sample using a grinding wheel or a grinding machine to make the weld smooth and flat.

[0017] The beneficial effects of this invention are: 1. The welding method for dissimilar alloy springs used in interventional treatment guidewires provided by this invention involves arranging a sparse section of a platinum alloy spring, a second brazing spring, a sparse section of a stainless steel spring, and a first brazing spring in sequence, and tightly fitting them onto the spring mounting portion of the nickel-titanium alloy memory wire in the guidewire body to form a welding area. This method uses spring-type brazing filler metal instead of the traditional brazing filler metal method, making the welding seam of dissimilar alloys tighter and overcoming the problems of uneven welding points and incomplete welding. Moreover, this method is simple, has low requirements for equipment and operators, low cost, and high production efficiency.

[0018] 2. The welding method for dissimilar alloy springs used in interventional treatment guidewires provided by this invention results in high welding strength between the springs, a smooth and flat welding surface, and the preservation of the superelasticity, flexibility, and visibility of the nickel-titanium alloy core wire, thus meeting the requirements for clinical use. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Appendix Figure 1 This is a flowchart of the welding method used in this invention; Appendix Figure 2 This is a schematic diagram of a stainless steel coiled spring structure. The left side represents the first sparse segment, and the right side represents the first conventional segment. Appendix Figure 3 This is a schematic diagram of a platinum alloy coiled spring structure. The left side represents the second sparse segment, and the right side represents the second conventional segment. Appendix Figure 4 This is a schematic diagram of the first brazing spring structure; Appendix Figure 5 This is a schematic diagram of the second brazing spring structure; Appendix Figure 6 This is a schematic diagram of the main structure of the nickel-titanium alloy memory wire guide wire; Appendix Figure 7 This is a schematic diagram of the structure of a stainless steel spring sleeve mounted on a nickel-titanium alloy memory wire spring. Appendix Figure 8 This is a schematic diagram of the structure after the first brazing spring is fitted onto the sparse section of the stainless steel coiled spring. Appendix Figure 9 This is a schematic diagram of the structure after the second brazing spring is fitted onto the sparse section of the stainless steel coiled spring. Appendix Figure 10 A schematic diagram of the structure of a platinum alloy spring sleeve mounted on a nickel-titanium alloy memory wire spring. Appendix Figure 11 This is an enlarged view of the welded area after the sample has been welded; Appendix Figure 12 This is a test diagram of the welded area connection strength after the sample welding was completed; In the diagram, 1 is a stainless steel coiled spring, 2 is a platinum alloy coiled spring, 3 is the first brazing spring, 4 is the coiled spring mounting position, and 5 is the second brazing spring. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All mentioned embodiments are implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the scope of protection of the present invention is not limited to the following embodiments.

[0022] This invention provides a welding method for dissimilar alloy springs used in interventional therapy guidewires. The method primarily involves embedding a spiral-shaped solder, i.e., a spring-shaped solder, into the gap between a stainless steel spring and a platinum alloy spring. The solder and spring are tightly fitted together before welding. An isolation gas is used for protection during the welding process, and the welding is completed using a brazing method. This welding method effectively solves the welding problem between the thin stainless steel spring and the platinum alloy spring, protecting not only the superelasticity and memory properties of the nickel-titanium alloy core wire but also ensuring the strength of the welded spring.

[0023] like Figure 1 As shown, the welding method of the present invention can be further divided into material preparation, brazing filler metal preparation, core wire grinding, assembly, welding, cooling annealing and post-treatment steps.

[0024] like Figures 2-6 As shown, a dissimilar alloy spring and a nickel-titanium alloy memory wire are prepared. The dissimilar alloy spring includes a stainless steel spring 1 (the first alloy spring) and a platinum alloy spring 2 (the second alloy spring). The nickel-titanium alloy memory wire serves as the main body of the interventional treatment guidewire. A brazing spring is also prepared, consisting of a first brazing spring 3 and a second brazing spring 5.

[0025] Regarding dissimilar alloy coiled springs, the stainless steel coiled spring 1 and the platinum alloy coiled spring 2 have the same wire diameter, the same inner diameter of the coil, and the same outer diameter of the spring coil. Both springs are divided into sparse and regular sections; that is, the stainless steel coiled spring 1 includes a first sparse section and a first regular section, while the platinum alloy coiled spring includes a second sparse section and a second regular section. The pitch of the regular section is 0mm, meaning the pitch of both the first and second regular sections is 0mm. The pitch of the sparse section is four times the wire diameter of the coiled spring. The length of the coiled spring is cut according to actual usage requirements.

[0026] Regarding the brazing springs, the first brazing spring 3 and the second brazing spring 5 have the same dimensions. Their wire diameters are the same as those of the stainless steel spring 1 and the platinum alloy spring 2, their pitch is four times the wire diameter, and their lengths are consistent with the length of the sparse sections of the stainless steel spring 1 and the platinum alloy spring 2. The inner and outer diameters of the coils of both are the same as those of the stainless steel spring 1 and the platinum alloy spring 2. The first and second brazing springs have the same composition, including tin, silver, or copper.

[0027] Regarding the main body of the interventional treatment guidewire, the spring mounting portion 4 of the nickel-titanium alloy memory wire is ground into a conical shape using a grinding machine. The maximum outer diameter of the conical portion is smaller than the inner diameter of the stainless steel spring 1 and the platinum alloy spring 2. The grinding length should be greater than or equal to the sum of the lengths of the stainless steel spring 1 and the platinum alloy spring 2. The diameter of the nickel-titanium alloy memory wire is the same as the outer diameter of the spring coil, and the length is cut according to the needs of use.

[0028] Preferably, the wire diameter of the stainless steel coiled spring 1 is R1, the wire diameter of the platinum alloy coiled spring 2 is R2, the pitch of the first sparse section is H1, and the pitch of the second sparse section is H2. Therefore, R1 = R2 = 0.03 ± 0.001 mm, and H1 = H2 = R1 × 4 = R2 × 4. The wire diameter of the first brazing spring 3 is R3, the wire diameter of the second brazing spring 5 is R4, the pitch of the first brazing spring 3 is H3, and the pitch of the second brazing spring 5 is H4. Therefore, R1 = R2 = R3 = R4, and H1 = H2 = H3 = H4. The length of the first sparse section is L1, the length of the second sparse section is L2, the length of the first brazing spring 3 is L3, and the length of the second brazing spring 5 is L4. Therefore, L1 = L2 = L3 = L4. The inner diameter of the stainless steel coil is A1, the inner diameter of the platinum alloy coil is A2, the inner diameter of the first brazed spring coil is A3, and the inner diameter of the second brazed spring coil is A4, so A1 = A2 = A3 = A4; the outer diameter of the stainless steel coil is B1, the outer diameter of the platinum alloy coil is B2, the outer diameter of the first brazed spring coil is B3, the outer diameter of the second brazed spring coil is B4, and the diameter of the nickel-titanium alloy memory wire is C, so B1 = B2 = B3 = B4 = C = 0.3 ± 0.01 mm. The maximum diameter of the conical spring mounting part 4 is D, so D < A1 or D < A2; the length of the conical spring mounting part 4 is L5, the length of the stainless steel spring 1 is L6, and the length of the platinum alloy spring 2 is L7, so L5 ≥ L6 + L7.

[0029] like Figures 7-10 As shown, first, the prepared stainless steel coiled spring 1 is fitted onto the conical coiled spring mounting part 4. Figure 7 ), wherein the first sparse section faces the tip of the cone; then the first brazing spring 3 is rotated and fitted onto the conical spring mounting part 4 along one side of the pitch gap of the first sparse section of the stainless steel coil spring 1. Figure 8 The second brazing spring 5 is rotated and fitted onto the conical spring mounting part 4 along the other side of the pitch gap of the first sparse section of the stainless steel spring 1. At this time, the first brazing spring 3 and the second brazing spring 5 are respectively located on both sides of the pitch gap of the stainless steel spring 1. Figure 9 Finally, the platinum alloy coiled spring 2 is fitted onto the conical coiled spring mounting part 4, so that the second sparse section is installed in the gap between the first brazing spring 3 and the second brazing spring 5, filling the pitch gap of the first sparse section of the stainless steel coiled spring 1. Figure 10 After assembly, the sparse section of the platinum alloy spring 2, the sparse section of the second brazing spring 5, the stainless steel spring 1, and the first brazing spring 3 are arranged in sequence, and the four of them are closely in contact with each other after being sleeved on the spring mounting part 4 of the nickel-titanium alloy memory wire of the guide wire body to form a welding area.

[0030] The assembled sample was placed on a vacuum adsorption platform and fixed under a negative pressure of -20 kPa to -50 kPa. A laser preheating beam with a power of 1 to 2 W was used to preheat the welding area to 100°C to 150°C for 10 to 20 seconds. Picosecond pulsed laser welding was performed with a power of 20 W to 25 W, a spot diameter of no more than 20 μm, and a scanning speed of no more than 2 mm / s. During the welding process, the wetting of the brazing filler spring was observed in real time, and the power was dynamically adjusted (±3 W) based on the feedback from the molten pool to prevent overheating of the platinum alloy spring 2.

[0031] After welding, the sample is placed in a constant temperature oven at 140℃~160℃ for annealing for no less than 30 minutes. Finally, the weldment is ground with a grinding wheel or grinder to make the weld joint flat, smooth, and without any rough feel.

[0032] Example 1 Material preparation: (1) Prepare a stainless steel spring 1 with a wire diameter R1 of 0.03mm, a length L6 of 300mm, an outer diameter B1 of 0.30mm, an inner diameter of 0.24mm, a first regular section pitch of 0mm, and a first sparse section pitch H1 of 0.12mm, wherein the length of the first sparse section L1 is 10mm; (2) Prepare a platinum alloy spring 2 with a wire diameter R2 of 0.03mm, a length L7 of 30mm, an outer diameter B2 of 0.30mm, a second regular section pitch of 0mm, and a second sparse section pitch H2 of 0.12mm, wherein the length of the second sparse section L2 is 10mm; (3) Prepare a nickel-titanium alloy memory wire with a diameter C of 0.30mm and a length of 500mm.

[0033] Solder preparation: Prepare two solder springs, the first solder spring 3 and the second solder spring 5, with identical specifications and dimensions. The wire diameters R3 and R4 are both 0.03mm, the outer diameters B3 and B4 of the coil are both 0.30mm, the inner diameter of the coil is 0.24mm, the pitches H3 and H4 are both 0.12mm, and the lengths L3 and L4 are both 10mm. The main component of the solder is lead-free solder paste.

[0034] Core wire grinding: The spring mounting part 4 of the nickel-titanium alloy memory wire is ground into a conical structure using a grinding machine. The grinding length L5 is 350mm and the diameter of the thinnest end of the cone is 0.12mm.

[0035] Assembly: Sleeve the stainless steel coiled spring 1 onto the coiled spring mounting part 4. Rotate the first brazing spring 3 along one side of the pitch gap of the first sparse section of the stainless steel coiled spring 1 onto the coiled spring mounting part 4. Rotate the second brazing spring 5 along the other side of the pitch gap of the first sparse section of the stainless steel coiled spring 1 onto the coiled spring mounting part 4. At this time, the first brazing spring 3 and the second brazing spring 5 are located on both sides of the pitch gap of the stainless steel coiled spring 1, respectively. Sleeve the platinum alloy coiled spring 2 onto the conical coiled spring mounting part 4, so that the second sparse section is installed in the gap between the first brazing spring 3 and the second brazing spring 5, filling the pitch gap of the first sparse section of the stainless steel coiled spring 1. Weld the assembled sample's first sparse section, first brazing spring, second brazing spring, and second sparse section as the welding area.

[0036] Welding: The assembled sample was fixed on a vacuum adsorption platform. A 2W laser preheating beam was used to preheat the welding area to 130°C for 15 seconds. Picosecond pulsed laser welding was performed with a power of 20W, a spot diameter of 20μm, and a scanning speed of 2mm / s. The wetting of the brazing filler metal was observed in real time during welding, and the power was dynamically adjusted between 20W and 3W based on the feedback from the molten pool to prevent overheating of the platinum alloy spring 2.

[0037] Cooling and annealing: After welding, place the weldment in a constant temperature oven at 150℃ for annealing for 30 minutes.

[0038] Post-processing: Use a grinding wheel or grinder to grind the welded parts to make the welded area flat, smooth, and without any rough feel.

[0039] After welding was completed, the morphology of the welded area in this embodiment is as follows: Figure 11 As shown. Thirty samples were randomly selected for testing, and their connection strength test results were as follows: Figure 12 As shown in Table 1.

[0040] Figure 11 The results show that after welding, the weld joint is smooth and flat, without cracks or brittle fractures. Figure 12 As shown in Table 1, the samples exhibit good consistency and high welding strength. The tested weld joint strength ranges from 5.055N to 6.839N, with an average joint strength of 5.946N. The samples retain the superelasticity, flexibility, and visibility of the nickel-titanium alloy core wire, meeting the requirements for clinical use.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for welding dissimilar alloy springs for interventional therapy guidewires, characterized in that, Includes the following steps: S1, Core wire grinding: Take a nickel-titanium alloy memory wire as the main body of the interventional treatment guide wire; grind the spring mounting part of the nickel-titanium alloy memory wire into a conical shape; S2, Spring Installation: (1) Take a stainless steel spring as the first alloy spring, the stainless steel spring including a first sparse section and a first regular section; put the stainless steel spring on the spring installation part; (2) Take the first brazing spring and the second brazing spring respectively and rotate them on both sides of the pitch gap of the first sparse section on the spring installation part, so that the first brazing spring and the second brazing spring are respectively located on both sides of the pitch gap of the stainless steel spring; (3) Take a platinum alloy spring as the second alloy spring, the platinum alloy spring including a second sparse section and a second regular section; put the platinum alloy spring on the spring installation part, the second sparse section is installed in the gap between the first brazing spring and the second brazing spring, filling the pitch gap of the first sparse section; S3, Spring Welding: The first sparse section, the first brazing spring, the second brazing spring, and the second sparse section of the sample assembled in S2 are used as the welding area. The sample is first treated with brazing process, and then cooled, annealed, and post-treated to complete the welding of dissimilar alloy springs.

2. The dissimilar alloy spring welding method for interventional guidewires as described in claim 1, characterized in that, The wire diameter of the stainless steel coiled spring is R1, the wire diameter of the platinum alloy coiled spring is R2, the pitch of the first sparse section is H1, and the pitch of the second sparse section is H2. R1=R2=0.03±0.001mm, and H1=H2=R1×4=R2×4.

3. The dissimilar alloy spring welding method for interventional guidewires as described in claim 2, characterized in that, The wire diameter of the first solder spring is R3, the wire diameter of the second solder spring is R4, the pitch of the first solder spring is H3, and the pitch of the second solder spring is H4, wherein R1=R2=R3=R4, and H1=H2=H3=H4.

4. The dissimilar alloy spring welding method for interventional guidewires as described in claim 3, characterized in that, The length of the first sparse segment is L1, the length of the second sparse segment is L2, the length of the first solder spring is L3, and the length of the second solder spring is L4; wherein L1 = L2 = L3 = L4.

5. The dissimilar alloy spring welding method for interventional guidewires as described in claim 1, characterized in that, The inner diameter of the coil of the stainless steel spring is A1, the inner diameter of the coil of the platinum alloy spring is A2, the inner diameter of the coil of the first brazing spring is A3, and the inner diameter of the coil of the second brazing spring is A4, where A1 = A2 = A3 = A4; the outer diameter of the coil of the stainless steel spring is B1, the outer diameter of the coil of the platinum alloy spring is B2, the outer diameter of the coil of the first brazing spring is B3, the outer diameter of the coil of the second brazing spring is B4, and the diameter of the nickel-titanium alloy memory wire is C, where B1 = B2 = B3 = B4 = C = 0.3 ± 0.01 mm.

6. The dissimilar alloy spring welding method for interventional guidewires as described in claim 5, characterized in that, The maximum diameter of the conical spring mounting part is D, where D < A1 or A2; the length of the conical spring mounting part is L5, the length of the stainless steel spring is L6, and the length of the platinum alloy spring is L7, where L5 ≥ L6 + L7.

7. The dissimilar alloy spring welding method for interventional guidewires as described in claim 1, characterized in that, The pitch of both the first and second conventional sections is 0 mm, and the components of the first and second brazed springs include tin, silver, or copper.

8. The method for welding dissimilar alloy springs for interventional guidewires as described in claim 1, characterized in that, The brazing process parameters are as follows: the sample is fixed on a vacuum adsorption platform in an argon atmosphere, and the welding area is preheated to 100℃~150℃ using a laser preheating beam with a power of 1~2W and a negative pressure of -20kPa~-50kPa for 10s~20s; the welding is performed using a picosecond pulsed laser with a power of 20w~25w, a spot diameter ≤20μm, and a scanning speed ≤2mm / s.

9. The dissimilar alloy spring welding method for interventional guidewires as described in claim 8, characterized in that, The cooling annealing process parameters are as follows: the brazed sample is placed in a constant temperature chamber at 140℃~160℃ for annealing for ≥30 minutes.

10. The dissimilar alloy spring welding method for interventional guidewires as described in claim 9, characterized in that, The post-processing process is as follows: the welding area of ​​the welded sample is ground using a grinding wheel or a grinding machine to make the weld smooth and flat.

Images