Medical guide wire and preparation process thereof

Abstract

The invention discloses a medical guide wire and a preparation process thereof, which comprises the following steps: providing a body blank of a stainless steel guide wire and a head blank of a nickel-titanium guide wire, heating the head blank to a temperature higher than the austenite phase transformation ending temperature, then bending and forming in a heating state, and quickly cooling by adopting compressed air to obtain the medical guide wire. The guide wire body is converted into a martensite phase to lock the shape, the guide wire body and the guide wire head are assembled into a positioning clamp, and the guide wire head is connected with the guide wire body through resistance butt welding; the method comprises the following steps of: in a pre-pressing stage, enabling a guide wire head to be in close contact with the end surface of a guide wire body through upsetting pressure; resistance heat is generated in the electrifying heating stage, and the contact area is heated to a plastic state; in the upsetting welding stage, upsetting pressure is increased while power is cut off or heating is maintained, so that the contact position is plastically deformed and welded; through the combination of the preset nickel-titanium head, the guide wire body and the solder mask, the high-strength and integrated connection with the stainless steel body is realized on the premise of not damaging the shape memory performance of the nickel-titanium.

Description

Technical Field

[0001] This invention relates to the field of medical guidewire technology, and in particular to a medical guidewire and its preparation process. Background Technology

[0002] Medical guidewires are key consumables used in interventional diagnostic and therapeutic procedures to guide vascular / luminal guiding devices (such as catheters, balloons, and stents) to the lesion site. They are widely used in minimally invasive interventional surgeries in cardiovascular, neurovascular, peripheral vascular, urological, and digestive diseases. Guidewires must simultaneously meet multiple performance requirements, including good tracking ability, controllable bending / rebound, low-friction surface, and biocompatibility. To achieve these requirements, a material partitioning design is often adopted: the guidewire body is made of materials such as stainless steel with high rigidity and torsional transmission performance, while the guidewire tip is made of alloys such as nickel-titanium with shape memory and superelasticity to improve the tracking and recovery capabilities of the soft end.

[0003] Existing heterogeneous guidewire connection methods mainly include laser welding, brazing / filler bonding, and bonding / pressing. Laser welding offers advantages such as localized heating and precise shaping, but the high energy density can easily generate a large heat-affected zone at the nickel-titanium end, leading to a shift in phase transition temperature and shape memory properties. Brazing requires the addition of filler metal, which may alter the mechanical and biocompatibility at the joint. Bonding methods lack long-term reliability under tensile, torque, and cyclic fatigue conditions. Based on the above, from the perspective of protecting the shape memory function of the nickel-titanium head and minimizing the heat-affected zone during the connection process, existing technologies have significant shortcomings: most thermal bonding methods struggle to provide sufficient interfacial bonding strength while strictly limiting heat input, thus causing phase transitions or mechanical property degradation in nickel-titanium; non-thermal methods (such as bonding or mechanical bonding) struggle to balance long-term mechanical strength with the low profile / low friction characteristics required clinically.

[0004] Therefore, how to minimize the thermal impact while ensuring the mechanical reliability of the joint has become a key technical problem in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a medical guidewire and its preparation process, thereby solving the above-mentioned technical problems.

[0006] To achieve this objective, the present invention adopts the following technical solution: A process for preparing a medical guidewire includes the following steps: S1, providing a stainless steel guide wire body blank and a nickel-titanium guide wire head blank, and performing end face machining and surface pretreatment on the body blank and head blank to obtain the guide wire body and guide wire head. S2, the head blank is subjected to hot bending and shaping treatment to form a guide wire head with a predetermined shape and shape memory effect; wherein, the hot bending and shaping treatment includes: heating the head blank to a temperature higher than its austenitic phase transformation completion temperature, then bending it in a heated state, and rapidly cooling it with compressed air to transform it into a martensitic phase to lock the shape. S3, the guidewire body and guidewire head are assembled into the positioning fixture, and the guidewire head is connected to the guidewire body using resistance welding. Post-weld processing is then performed to obtain an integrated medical guidewire. The resistance welding process is resistance butt welding, and its steps include: Pre-compression stage: The guide wire head is brought into close contact with the end face of the guide wire body by the upsetting pressure; During the energized heating stage: the current passes through the contact surface and generates resistance heat, heating the contact area to a plastic state; Upsetting and welding stage: While the power is off or heating is maintained, the upsetting pressure is increased to cause plastic deformation and welding at the contact point.

[0007] S3, the guidewire body and guidewire head are assembled into the positioning fixture, the guidewire head is connected to the guidewire body by resistance welding, and then post-weld treatment is performed to obtain an integrated medical guidewire.

[0008] Optionally, in step S1, the end face machining and surface pretreatment of the body blank includes finishing the stainless steel guide wire body blank using an electrolytic grinding process; wherein, during electrolytic grinding, the electrolyte flows through the machining gap between the tool cathode and the workpiece anode at a flow rate of 5~60m / s.

[0009] Optionally, step S1 specifically includes: S11, stainless steel wire is selected as the guide wire body blank and nickel-titanium alloy wire is selected as the guide wire head blank, and the blanks are cut and cut according to the design diameter and length tolerance. S12, apply constant tension to the blank of the guide wire body after blanking, and use electrolytic grinding process to finish its outer cylindrical surface and target taper area during its axial feeding process to obtain target size, surface roughness and coaxiality. S13, perform synchronous end face milling on one end of the guide wire body blank and one end of the guide wire head blank after electrolytic grinding, so that the two end faces meet the preset flatness requirements.

[0010] Optionally, step S13 may be followed by: S14. The guide wire body blank and the guide wire head blank with the precision-machined end face are placed in a multi-tank ultrasonic cleaning basket and then subjected to ultrasonic cleaning with alkaline solution, rinsing with deionized water and dehydration with anhydrous ethanol, and then dried. S15. Use an automatic optical image measuring instrument to inspect the end face morphology and key dimensions of the dried guide wire body blank and guide wire head blank. Qualified products are transferred to the next process as guide wire body and guide wire head.

[0011] Optionally, step S2 specifically includes: S21, fix the guide wire head blank on a special shaping fixture, and heat the head blank to a temperature higher than its austenitic phase transformation completion temperature; S22, during the heat preservation stage, a multi-angle bending mechanism driven by a servo motor applies bending force to the guide wire head blank heated to the austenitic phase, so that it is formed into a predetermined shape along a preset curve mold. S23, immediately after forming, the surrounding compressed air cooling system is activated to perform directional rapid cooling of the bent part at a cooling rate of ≥30℃ / second, so that the nickel-titanium alloy is transformed from the austenitic phase to the martensitic phase; S24. Place the cooled guide wire head in a low-temperature heat treatment furnace for stress relief treatment. Keep it at 250-350℃ for 5-15 minutes, and then cool it to room temperature with the furnace. S25, a shape scanner is used to measure the contour accuracy and bending angle of the shaped guide wire head, and qualified products are transferred to the welding process.

[0012] Optionally, step S21 specifically includes: fixing and clamping the guide wire head blank using a special shaping fixture, locally heating the fixed guide wire head blank using a medium-frequency induction heating device, and monitoring the heating temperature in real time using an infrared thermometer to uniformly raise it to a set temperature 20-50°C higher than the austenitic phase transformation end point Af temperature of nickel-titanium alloy.

[0013] Optionally, the clamping surface of the special shaping fixture is provided with a high-temperature resistant ceramic coating to prevent surface adhesion.

[0014] Optionally, step S3 specifically includes: S31, the guide wire body and the treated guide wire head are respectively installed into the positioning fixture with a fine adjustment structure. The elastic clamping unit built into the positioning fixture protects and fixes the shaped area of ​​the guide wire head, while ensuring that the guide wire body and the end face to be welded are fitted without gaps. S32, start the resistance welding equipment and execute the pre-pressing stage, the power heating stage and the upsetting welding stage in sequence; S33, after welding is completed, the integrated wire guide blank is transferred to the online processing station, where the weld area is polished and ultrasonically cleaned in sequence; S34. The welded joint is inspected for quality. After being marked as qualified, it is transferred to the packaging process as an integrated medical guide wire finished product.

[0015] The present invention also provides a medical guidewire, which is manufactured using the medical guidewire manufacturing process described above. The medical guidewire includes a guidewire body made of stainless steel and a guidewire head made of nickel-titanium alloy. The guidewire head has a predetermined bending shape formed by hot bending and has a shape memory effect. The guide wire body and the guide wire head are integrated into a welded joint through a resistance welding process.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Stainless steel is used as the guidewire body blank and nickel-titanium is used as the guidewire head blank. Both are subjected to end-face finishing, degreasing, and surface pretreatment to obtain the guidewire body and guidewire head to be processed. Then, the guidewire head is hot-bent and shaped by heating to the corresponding phase transformation temperature, bending according to the designed arc, and rapid cooling, so that the guidewire head forms a predetermined geometry and possesses the target shape memory characteristics. The processed guidewire body and the shaped guidewire head are installed in a special positioning fixture to ensure axial concentricity and end-face fit. A controlled resistance welding process is used to complete the connection between the two under pre-pressing, electric heating, and upsetting conditions. Finally, the welded body is cleaned after welding, and necessary surface finishing and quality inspection are performed to obtain an integrated medical guidewire product. This process, through the pre-shaped nickel-titanium head, guidewire body, and resistance welding, achieves a high-strength, integrated connection with the stainless steel body without compromising the shape memory properties of nickel-titanium. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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.

[0018] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0019] Figure 1 This is a schematic flowchart of the preparation process of the medical guidewire in this embodiment 1; Figure 2 This is a schematic diagram of the clamping process for the heat bending and shaping of the medical guidewire in this embodiment 1; Figure 3 This is a schematic diagram of the welding joint of the medical guidewire in this embodiment 2. Detailed Implementation

[0020] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1: Combination Figure 1 As shown, this embodiment of the invention provides a process for preparing a medical guidewire, including the following steps: S1 provides a stainless steel guide wire body blank and a nickel-titanium guide wire head blank, and performs end face machining and surface pretreatment on the body blank and head blank to obtain the guide wire body and guide wire head. Electrolytic grinding, a non-contact, stress-free special processing method, is used to precision machine the stainless steel guide wire body to obtain high-precision diameter, taper, and surface finish. Simultaneously, the guide wire head and the end faces to be welded to the body undergo precision machining and cleaning to ensure that the end faces are flat, clean, and free of oxide layers, laying a solid foundation for subsequent high-quality welding of dissimilar materials.

[0024] S2, hot bending and shaping treatment of the head blank, which is formed into a predetermined shape and has a shape memory effect by heating, bending and rapid cooling; Utilizing the shape memory effect of nickel-titanium alloys, a series of thermal cycles involving precisely controlled heating (above the austenitic phase transformation temperature), bending, and rapid cooling with compressed air are used to process the guidewire tip into a predetermined curved shape. Rapid cooling transforms it into the martensitic phase, thus "locking" in the shape, ultimately resulting in a guidewire tip with a stable shape memory effect and the desired compliance.

[0025] S3. The guidewire body and guidewire head are assembled into the positioning fixture. The guidewire head is connected to the guidewire body using resistance welding. After welding, post-weld treatment is performed to obtain an integrated medical guidewire.

[0026] Resistance welding is employed to control parameters such as pre-pressure, welding current, time, and upsetting pressure. This generates localized resistance heat, bringing the contact surfaces to a plastic state before pressure welding, achieving a high-strength connection between the nickel-titanium guidewire head and the stainless steel guidewire body. Subsequent post-weld treatments (such as polishing and inspection) are used to remove weld spatter, clean the surface, and ensure joint quality, ultimately producing a reliable integrated medical guidewire.

[0027] The working principle of this invention is as follows: Stainless steel is used as the guidewire body blank and nickel-titanium is used as the guidewire head blank. Both are subjected to end face finishing, degreasing, and surface pretreatment to obtain the guidewire body and guidewire head to be processed. Then, the guidewire head is hot-bent and shaped by heating to the corresponding phase transformation temperature, bending according to the designed arc, and rapid cooling to form a predetermined geometry and possess the target shape memory characteristics. The processed guidewire body and the shaped guidewire head are installed in a special positioning fixture to ensure axial concentricity and end face fit. The connection between the two is completed by a controlled resistance welding process under pre-pressing, electric heating, and upsetting conditions. Finally, the welded body is cleaned after welding, and necessary surface finishing and quality inspection are carried out to obtain an integrated medical guidewire product. This process achieves a high-strength, integrated connection with the stainless steel body without damaging the shape memory properties of nickel-titanium through the combination of the pre-shaped nickel-titanium head, guidewire body, and resistance welding.

[0028] In this embodiment, in step S1, the end face machining and surface pretreatment of the body blank includes finishing the stainless steel guide wire body blank using an electrolytic grinding process; wherein, during electrolytic grinding, the electrolyte flows through the machining gap between the tool cathode and the workpiece anode at a flow rate of 5~60m / s.

[0029] During machining, the guide wire body is fed axially and a constant tension is applied to maintain coaxiality and straightness. The guide wire acts as the anode, and the machining tool acts as the cathode. The electrolyte flows through the machining gap between the tool cathode and the workpiece anode at a velocity of 5–60 m / s. Non-contact metal removal is achieved through an electrochemical reaction, thereby obtaining the desired outer diameter, taper area, and surface roughness. This process avoids residual stress and microcracks caused by traditional mechanical cutting, and effectively removes barbs and burrs, ensuring the geometric accuracy and coaxiality of the end face and outer circle, facilitating subsequent end face bonding and welding.

[0030] During processing, the temperature and cleanliness of the electrolyte should be controlled and a circulating filtration device should be installed to prevent particulate matter from being trapped. After processing, the end face should be ultrasonically cleaned, rinsed with deionized water and dehydrated with alcohol, and the end face morphology and key dimensions should be inspected with an automatic optical image measuring instrument.

[0031] In this embodiment, in step S2, the hot bending and shaping process includes: heating the head blank to a temperature higher than its austenitic phase transformation completion temperature, then bending it while it is heated, and rapidly cooling it with compressed air to transform it into a martensitic phase to lock the shape.

[0032] It should be noted that the guide wire head blank is made of nickel-titanium alloy wire, which needs to be hot-bent to obtain a stable predetermined bending shape and form a shape memory effect. The nickel-titanium head is fixed on a special shaping fixture (the clamping surface can be coated with a high-temperature resistant ceramic coating to prevent adhesion and surface damage). The heating zone is heated to a value higher than the austenitic phase transformation end temperature Af of the nickel-titanium alloy using induction or other local heating devices (usually it is preferable to have Af floated by a certain temperature difference to ensure complete austenite formation). In the heated state, the bending mechanism driven by a servo is used to gradually shape the wire into the target curve according to the preset mold.

[0033] Immediately after forming, the bent portion is subjected to directional rapid cooling (e.g., using a surrounding compressed air cooling device) to achieve a rapid phase transformation from austenite to martensite and "lock" in the shape, thereby obtaining the desired shape memory and superelastic properties. This hot-forming-rapid cooling process, by controlling the heating temperature, holding time, forming speed, and cooling rate, ensures geometric accuracy while maximizing the protection of nickel-titanium's shape memory properties and minimizing adverse effects on the material's microstructure and mechanical properties.

[0034] In this embodiment, step S1 specifically includes: S11, stainless steel wire is selected as the guide wire body blank and nickel-titanium alloy wire is selected as the guide wire head blank, and the blanks are cut and cut according to the design diameter and length tolerance. Stainless steel wire is selected as the guide wire body blank, and nickel-titanium alloy wire is selected as the guide wire head blank. The stainless steel material can be 304 or 316L stainless steel wire. According to the design drawings and tolerance requirements, CNC precision cutting equipment is used to cut the raw materials to the specified length and diameter range. At the same time, the cut ends are initially deburred and batch-marked for traceability. The cutting dimensions should meet the subsequent processing allowance requirements, and incoming inspection records should be made during the warehousing / transfer process. Materials with dimensional or surface defects should be reworked or rejected according to the non-conforming handling procedure.

[0035] S12, apply constant tension to the blank of the guide wire body after blanking, and use electrolytic grinding process to finish its outer cylindrical surface and target taper area during its axial feeding process to obtain target size, surface roughness and coaxiality. After blanking, the guide wire blank is tensioned in a machining fixture under constant tension to maintain axial straightness and coaxiality. During the axial feed process, electrochemical grinding (electrochemical machining) is used to finish the outer diameter and target taper area of ​​the guide wire. During electrochemical grinding, the guide wire acts as the workpiece anode and the machining tool as the cathode. The electrolyte flows through the gap between the tool cathode and the workpiece anode at a velocity of approximately 5–60 m / s. Machining parameters (current density, feed rate, gap, temperature) are controlled according to the process card to obtain the required outer diameter, taper, surface roughness, and coaxiality. This process effectively removes burrs, reduces residual stress, and ensures the smoothness of the outer diameter. After machining, the surface should be initially inspected, and the machining batch and parameters should be recorded.

[0036] S13, perform synchronous end face milling on one end of the guide wire body blank and one end of the guide wire head blank after electrolytic grinding, so that the two end faces meet the preset flatness requirements.

[0037] The guide wire body, which has undergone electrolytic grinding, and the guide wire head blank are subjected to simultaneous end face milling or end face finishing processes to ensure that both ends meet the preset flatness, perpendicularity, and geometric tolerance requirements. Simultaneous machining can use dual-station or coaxial fixtures to ensure the consistency of the end face position relationship. After milling, the end faces are deburred to eliminate minor flash and prevent fixture indentations.

[0038] S14. The guide wire body blank and the guide wire head blank with the precision-machined end face are placed in a multi-tank ultrasonic cleaning basket and then subjected to ultrasonic cleaning with alkaline solution, rinsing with deionized water and dehydration with anhydrous ethanol, and then dried. The guide wire body blank and the guide wire head blank with the precision-machined end face are placed in a multi-tank ultrasonic cleaning basket. They are then ultrasonically cleaned in an alkaline solution to remove oil and processing residue, rinsed with deionized water to remove residual alkali, and dehydrated using anhydrous ethanol or an equivalent dehydrating medium. Finally, they are dried in a clean environment (such as a clean oven or constant temperature drying oven) to avoid secondary surface contamination.

[0039] S15. Use an automatic optical image measuring instrument to inspect the end face morphology and key dimensions of the dried guide wire body blank and guide wire head blank. Qualified products are transferred to the next process as guide wire body and guide wire head.

[0040] After drying, an automated optical image measuring instrument is used to perform online inspection and recording of key dimensions such as end face morphology, flatness, diameter, taper start and end positions, and coaxiality of the guidewire body and head. Inspection uses pre-set acceptance thresholds. Qualified products are marked with batch and acceptance tags in the system and transferred to the next process (such as head shaping or assembly welding). Non-conforming parts are handled according to rework or scrap procedures, and the reasons and results are recorded.

[0041] In this embodiment, step S2 specifically includes: S21, fix the guide wire head blank on a special shaping fixture, use a medium frequency induction heating device to locally heat the fixed guide wire head blank, and monitor the heating temperature in real time with an infrared thermometer to make it rise evenly to a set temperature 20-50℃ higher than the end point Af temperature of the austenitic phase transformation of nickel-titanium alloy. Combination Figure 2 As shown, there is a special shaping fixture, where 1 is the guide wire body and 2 is the guide wire head. The black screws distributed around the guide wire body 1 and the guide wire head 2 are adjustable screws, which can be adjusted according to the needs of use, so that the guide wire head 2 can be heated and shaped to a preset curvature.

[0042] It should be noted that the pre-cleaned and inspected guide wire head blank is fixed in a dedicated shaping fixture. The clamping surface of the fixture can be coated with a high-temperature resistant ceramic coating to prevent adhesion or clamping marks on the heated surface. A medium-frequency induction heating device is used to locally and rapidly heat the head blank fixed in the fixture. The temperature field of the heated area is monitored in real time by an infrared thermometer or a contact miniature thermocouple. The heated area is controlled to uniformly rise to a value higher than the set value of the austenitic phase transformation completion temperature Af of the nickel-titanium alloy (preferably Af 20-50 °C higher), and maintained at the predetermined holding time to ensure that the heated area fully completes the austenitic phase transformation, thereby providing a uniform metallographic state for subsequent plastic forming. Over-temperature protection and temperature gradient limitation should be set in the heating process to avoid excessive heat influence from adjacent unheated areas.

[0043] S22, during the heat preservation stage, a multi-angle bending mechanism driven by a servo motor applies bending force to the guide wire head blank heated to the austenitic phase, so that it is formed into a predetermined shape along a preset curve mold. Once the heating zone reaches and stabilizes at the set temperature, the heat preservation and forming stage begins. A multi-angle bending mechanism driven by a servo motor gradually applies controllable bending force to the head blank while it is in heat preservation mode, shaping it into the target geometry along a preset curved mold or forming contour. The multi-angle bending mechanism enables segmented or progressively approximating forming strategies to reduce localized overplasticization and control elastic rebound. The forming rate, segment angles, and support positions of the conforming fixtures are all set and recorded according to the process documents to ensure contour accuracy.

[0044] S23, immediately after forming, the surrounding compressed air cooling system is activated to perform directional rapid cooling of the bent part at a cooling rate of ≥30℃ / second, so that the nickel-titanium alloy is transformed from the austenitic phase to the martensitic phase; Immediately after forming, a surrounding compressed air cooling system or an equivalent directional cooling device is activated to rapidly cool the bent areas, achieving a rapid austenite-to-martensite phase transformation and locking in the formed shape. The cooling device should be able to achieve a controlled cooling rate (e.g., a local cooling rate ≥ 30 ℃ / s), and the cooling curve should be recorded and verified using thermocouples or infrared thermometry. The direction, flow rate, and temperature distribution of the cooling airflow must be designed to avoid adverse effects on other functional areas of the head. Directional rapid cooling can significantly reduce the heat-affected zone, improve the stability of shape memory performance, and reduce the need for subsequent straightening or rework.

[0045] S24. Place the cooled guide wire head in a low-temperature heat treatment furnace for stress relief treatment. Keep it at 250-350℃ for 5-15 minutes, and then cool it to room temperature with the furnace. The rapidly cooled and initially inspected wire tips can be placed in a low-temperature heat treatment furnace for stress relief to further stabilize material properties and reduce residual forming stress. The heat treatment is carried out at 250–350 °C for 5–15 minutes (the specific temperature and time are optimized based on the alloy composition and previous heating history), followed by furnace cooling to room temperature. The aim is to improve fatigue performance and dimensional stability without significantly altering the memory properties and phase transformation temperature of the nickel-titanium alloy. Temperature profiles of the heat treatment process should be recorded and archived by batch.

[0046] S25, a shape scanner is used to measure the contour accuracy and bending angle of the shaped guide wire head, and qualified products are transferred to the welding process.

[0047] After stress relief treatment and cooling to room temperature, the shaped guide wire head is comprehensively measured for contour accuracy, bending angle, radius, and related geometric tolerances using a shape scanner, coordinate measuring machine, or image measuring equipment. The measurement data is then compared with preset tolerance thresholds. Guide wire heads that pass the measurement are labeled in batches and transferred to the assembly and welding process; heads that fail the measurement are handled according to the rework or scrapping process, and the non-conformities and handling results are recorded.

[0048] As a preferred embodiment, the clamping surface of the special shaping fixture is provided with a high-temperature resistant ceramic coating to prevent surface adhesion, thereby preventing the nickel-titanium guide wire head surface from adhering to the clamping surface or generating adhesive residue during heating, forming and rapid cooling.

[0049] In this embodiment, specifically, in step S3, the resistance welding process is resistance butt welding, and the process includes: Pre-compression stage: The forging pressure is used to make the guide wire head and the end face of the guide wire body in close contact; During the energized heating stage: the current passes through the contact surface and generates resistance heat, heating the contact area to a plastic state; Upsetting and welding stage: While the power is off or heating is maintained, the upsetting pressure is increased to cause plastic deformation and welding at the contact point.

[0050] It should be noted that, firstly, during the pre-pressing stage, a controllable pre-pressure is applied using an upsetting device to achieve a tight, gapless contact between the two end faces and eliminate interfacial air and small particles; subsequently, during the energizing heating stage, energization is performed according to a set current / voltage curve, causing the current to generate local resistance heat on the contact surface, raising the temperature until the contact area enters a plastic state (the temperature and heating time are determined by the material type, diameter, and contact resistance). The entire energizing process should be monitored and recorded online for current, voltage, contact resistance, and temperature to control heat input; finally, during the upsetting welding stage, the power is cut off at an appropriate time or the upsetting pressure is increased while maintaining a low current, causing controlled plastic flow in the contact area and forming a metallurgical or mechanical bond.

[0051] Welding fixtures should be made of electrode materials with good conductivity and wear resistance (such as copper-based alloys), and should be equipped with electrode cooling, fixture protection, and post-weld online cleaning (polishing / ultrasonic cleaning) and non-destructive testing procedures to ensure joint strength, surface quality and minimal thermal impact on the shape memory performance of the nickel-titanium head.

[0052] In this embodiment, step S3 specifically includes: S31, the guide wire body and the treated guide wire head are respectively installed into the positioning fixture with a fine adjustment structure. The elastic clamping unit built into the positioning fixture protects and fixes the shaped area of ​​the guide wire head, while ensuring that the guide wire body and the end face to be welded are fitted without gaps. The pre-processed and inspected guide wire body and guide wire head are respectively installed into a dedicated positioning fixture. This fixture has a fine-tuning structure (e.g., radial and axial fine-tuning screws, micro-displacement stages, or micron-level lead screws) for precise adjustment, achieving high-precision alignment of the two parts in three dimensions. The fixture's built-in elastic clamping unit (e.g., elastic pads, spring clips, or silicone buffers) provides protective fixation for the shaped area of ​​the guide wire head, preventing compression or scratches during clamping and absorbing minor vibrations. The fine-tuning mechanism gradually brings the guide wire body and guide wire head closer together until a gapless fit is achieved. After alignment, an optical imaging system or displacement sensor can be used to confirm and record the coaxiality, end-face gap, and end-face normal deviation online.

[0053] S32, start the resistance welding equipment and execute the pre-pressing stage, the power heating stage and the upsetting welding stage in sequence; The entire welding process should be monitored and recorded online for parameters such as current, voltage, contact resistance, upsetting force, displacement (or displacement increment), and necessary temperature. Automatic stop and alarm logic should be provided for exceeding limits to ensure safety.

[0054] S33. After welding is completed, the integrated wire guide blank is transferred to the online processing station for polishing and ultrasonic cleaning of the weld area. The polishing is carried out by electrolytic polishing, using a neutral salt solution as the electrolyte.

[0055] After polishing, the parts are subjected to ultrasonic cleaning (deionized water / suitable cleaning agent), deionized water rinsing and anhydrous ethanol dehydration in sequence, and finally dried in a clean environment to remove residual ions and organic matter.

[0056] S34. The welded joint is inspected for quality. After being marked as qualified, it is transferred to the packaging process as an integrated medical guide wire finished product.

[0057] The inspection includes visual and surface integrity checks (observation under a magnifying glass or microscope), measurement of end face and joint geometry, weld resistance measurement, tensile / pull-out strength testing of joints, and torque transmission performance testing. Additionally, fatigue cycle testing or metallographic / cross-sectional analysis can be performed according to a sampling plan to assess interface bonding quality (destructive testing is performed according to the sampling ratio and the results are recorded). All inspection data are archived by batch. Qualified products, after being identified and their batch / work order number recorded, are transferred as integrated medical guidewires to subsequent surface treatment, sterilization, and packaging processes. Non-conforming products are handled according to rework or scrap procedures, and the reasons for non-conformity and the disposal results are recorded.

[0058] Example 2: Combination Figure 3 As shown, the present invention also provides a medical guidewire, which is prepared by the medical guidewire manufacturing process as described in Example 1. The medical guidewire includes a guidewire body 1 made of stainless steel and a guidewire head 2 made of nickel-titanium alloy. The guidewire head 2 has a predetermined bending shape formed by hot bending and has a shape memory effect. The guidewire body 1 and the guidewire head 2 are integrated into a welded joint 3 by resistance welding.

[0059] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A manufacturing process for a medical guidewire, characterized in that, Includes the following steps: S1, providing a stainless steel guide wire body blank and a nickel-titanium guide wire head blank, and performing end face machining and surface pretreatment on the body blank and head blank to obtain the guide wire body and guide wire head. S2, the head blank is subjected to hot bending and shaping treatment to form a guide wire head with a predetermined shape and shape memory effect; wherein, the hot bending and shaping treatment includes: heating the head blank to a temperature higher than its austenitic phase transformation completion temperature, then bending it in a heated state, and rapidly cooling it with compressed air to transform it into a martensitic phase to lock the shape. S3, the guidewire body and guidewire head are assembled into the positioning fixture, the guidewire head is connected to the guidewire body by resistance welding, and then post-weld treatment is performed to obtain an integrated medical guidewire.

2. The preparation process of the medical guidewire according to claim 1, characterized in that, In step S1, the end face machining and surface pretreatment of the body blank includes finishing the stainless steel guide wire body blank using an electrolytic grinding process; wherein, during electrolytic grinding, the electrolyte flows through the machining gap between the tool cathode and the workpiece anode at a flow rate of 5~60m / s.

3. The preparation process of the medical guidewire according to claim 1, characterized in that, in, The resistance welding process is resistance butt welding, and its process includes: Pre-compression stage: The guide wire head is brought into close contact with the end face of the guide wire body by the upsetting pressure; During the energized heating stage: the current passes through the contact surface and generates resistance heat, heating the contact area to a plastic state; Upsetting and welding stage: While the power is off or heating is maintained, the upsetting pressure is increased to cause plastic deformation and welding at the contact point.

4. The preparation process of the medical guidewire according to claim 1, characterized in that, Step S1 specifically includes: S11, stainless steel wire is selected as the guide wire body blank and nickel-titanium alloy wire is selected as the guide wire head blank, and the blanks are cut and cut according to the design diameter and length tolerance. S12, apply constant tension to the blank of the guide wire body after blanking, and use electrolytic grinding process to finish its outer cylindrical surface and target taper area during its axial feeding process to obtain target size, surface roughness and coaxiality. S13, perform synchronous end face milling on one end of the guide wire body blank and one end of the guide wire head blank after electrolytic grinding, so that the two end faces meet the preset flatness requirements.

5. The preparation process of the medical guidewire according to claim 4, characterized in that, Following step S13, the following is also included: S14. The guide wire body blank and the guide wire head blank with the precision-machined end face are placed in a multi-tank ultrasonic cleaning basket and then subjected to ultrasonic cleaning with alkaline solution, rinsing with deionized water and dehydration with anhydrous ethanol, and then dried. S15. Use an automatic optical image measuring instrument to inspect the end face morphology and key dimensions of the dried guide wire body blank and guide wire head blank. Qualified products are transferred to the next process as guide wire body and guide wire head.

6. The preparation process of the medical guidewire according to claim 1, characterized in that, Step S2 specifically includes: S21, fix the guide wire head blank on a special shaping fixture, and heat the head blank to a temperature higher than its austenitic phase transformation completion temperature; S22, during the heat preservation stage, a multi-angle bending mechanism driven by a servo motor applies bending force to the guide wire head blank heated to the austenitic phase, so that it is formed into a predetermined shape along a preset curve mold. S23, immediately after forming, the surrounding compressed air cooling system is activated to perform directional rapid cooling of the bent part at a cooling rate of ≥30℃ / second, so that the nickel-titanium alloy is transformed from the austenitic phase to the martensitic phase; S24. Place the cooled guide wire head in a low-temperature heat treatment furnace for stress relief treatment. Keep it at 250-350℃ for 5-15 minutes, and then cool it to room temperature with the furnace. S25, a shape scanner is used to measure the contour accuracy and bending angle of the shaped guide wire head, and qualified products are transferred to the welding process.

7. The preparation process of the medical guidewire according to claim 6, characterized in that, Step S21 specifically includes: fixing and clamping the guide wire head blank using a special shaping fixture, locally heating the fixed guide wire head blank using a medium frequency induction heating device, and monitoring the heating temperature in real time using an infrared thermometer to uniformly raise it to a set temperature 20-50°C higher than the austenitic phase transformation end point Af temperature of nickel-titanium alloy.

8. The preparation process of the medical guidewire according to claim 7, characterized in that, The clamping surface of the special shaping fixture is coated with a high-temperature resistant ceramic coating to prevent surface adhesion.

9. The preparation process of the medical guidewire according to claim 8, characterized in that, Step S3 specifically includes: S31, the guide wire body and the treated guide wire head are respectively installed into the positioning fixture with a fine adjustment structure. The elastic clamping unit built into the positioning fixture protects and fixes the shaped area of ​​the guide wire head, while ensuring that the guide wire body and the end face to be welded are fitted without gaps. S32, start the resistance welding equipment and execute the pre-pressing stage, the power heating stage and the upsetting welding stage in sequence; S33, after welding is completed, the integrated wire guide blank is transferred to the online processing station, where the weld area is polished and ultrasonically cleaned in sequence; S34. The welded joint is inspected for quality. After being marked as qualified, it is transferred to the packaging process as an integrated medical guide wire finished product.

10. A medical guidewire, characterized in that, The medical guidewire is manufactured using the manufacturing process described in any one of claims 1 to 9. The medical guidewire includes a guidewire body (1) made of stainless steel and a guidewire head (2) made of nickel-titanium alloy. The guidewire head (2) has a predetermined bending shape formed by hot bending and has a shape memory effect. The guide wire body (1) and the guide wire head (2) are integrated into a welded joint through resistance welding.

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