Forming methods and systems for nickel-titanium thin-walled tubes

Abstract

This application relates to a forming method and system for nickel-titanium thin-walled tubes. The method includes: during the forming process of the nickel-titanium thin-walled tube to be formed, performing auxiliary forming treatment on the nickel-titanium thin-walled tube according to an auxiliary forming method, and determining the forming parameters of the nickel-titanium thin-walled tube; the auxiliary forming method includes at least one of pulsed current assisted forming method and ultrasonic vibration assisted forming method; adjusting the auxiliary forming method according to the forming parameters, so that the forming parameters corresponding to the adjusted auxiliary forming method are within a preset forming parameter range; and performing auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method to obtain the formed nickel-titanium thin-walled tube. This method enables the forming result of medical nickel-titanium micro-thin-walled tubes to balance geometric accuracy, surface integrity, and functional consistency.

Description

Technical Field

[0001] This application relates to the field of precision machining technology for medical metal materials, and in particular to a forming method and forming system for a nickel-titanium thin-walled tube. Background Technology

[0002] Nickel-titanium alloys possess excellent shape memory effect, superelasticity, and biocompatibility, making them widely used in high-end interventional medical devices such as vascular stents and thrombectomy instruments. Nickel-titanium micro-thin-walled tubes, as the core substrate of these devices, directly affect the fatigue life and operational stability of the finished medical devices due to their dimensional accuracy, wall thickness uniformity, surface integrity, and phase transformation properties.

[0003] Currently, medical nickel-titanium micro-thin-walled tubes are generally formed using traditional processes involving multi-pass drawing, diameter reduction, annealing, straightening, and finishing. While this process can complete the basic forming of the tube, defects such as roundness deviation, local collapse, and uneven wall thickness are prone to occur during processing. Moreover, the frictional resistance at the forming contact surface is relatively high, easily causing surface scratches, thickening of the defect layer, and even microcracks. In addition, traditional processes cannot precisely control local stress and temperature changes during forming, which can easily lead to fluctuations in the material's phase transformation properties. Furthermore, since process parameters mainly rely on manual experience for setting, current processing methods cannot simultaneously control cross-sectional deformation, surface damage, and phase transformation property fluctuations, resulting in a forming result that cannot simultaneously achieve geometric accuracy, surface integrity, and functional consistency. Summary of the Invention

[0004] Therefore, it is necessary to provide a method, system, apparatus, computer equipment, computer-readable storage medium, and computer program product for forming nickel-titanium thin-walled tubes that can take into account geometric accuracy, surface integrity, and functional consistency, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a method for forming a nickel-titanium thin-walled tube, comprising:

[0006] During the forming process of the nickel-titanium thin-walled tube to be formed, the nickel-titanium thin-walled tube is subjected to auxiliary forming process according to the auxiliary forming method, and the forming parameters of the nickel-titanium thin-walled tube are determined; the auxiliary forming method includes at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method.

[0007] The auxiliary forming method is adjusted according to the forming parameters so that the forming parameters corresponding to the adjusted auxiliary forming method are within the preset forming parameter range.

[0008] According to the adjusted auxiliary forming method, the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment to obtain the formed nickel-titanium thin-walled tube.

[0009] Secondly, this application also provides a forming system for nickel-titanium thin-walled tubes, the system comprising a controller, a mold, and a mandrel; the mold is placed outside the nickel-titanium thin-walled tube to be formed, for defining the outer contour of the nickel-titanium thin-walled tube; the mandrel is placed inside the cavity of the nickel-titanium thin-walled tube, for supporting the nickel-titanium thin-walled tube; the controller is used to execute the steps of the method described in the first aspect above.

[0010] Thirdly, this application also provides a forming apparatus for nickel-titanium thin-walled tubes, comprising:

[0011] The loading module is used to perform auxiliary forming processing on the nickel-titanium thin-walled tube according to the auxiliary forming method during the forming process of the nickel-titanium thin-walled tube to be formed, and to determine the forming parameters of the nickel-titanium thin-walled tube; the auxiliary forming method includes at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method.

[0012] An adjustment module is used to adjust the auxiliary forming method according to the forming parameters, so that the forming parameters corresponding to the adjusted auxiliary forming method are within a preset forming parameter range;

[0013] The forming module is used to perform auxiliary forming processing on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method, so as to obtain the formed nickel-titanium thin-walled tube.

[0014] Fourthly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect above.

[0015] Fifthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect above.

[0016] Sixthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in the first aspect above.

[0017] The aforementioned method, system, apparatus, computer equipment, computer-readable storage medium, and computer program product for forming nickel-titanium thin-walled tubes, by performing auxiliary forming treatment on the nickel-titanium thin-walled tube to be formed according to an auxiliary forming method during the forming process, and determining the forming parameters of the nickel-titanium thin-walled tube, including at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method, adjusts the auxiliary forming method according to the forming parameters so that the forming parameters corresponding to the adjusted auxiliary forming method are within a preset forming parameter range, and performs auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method to obtain the formed nickel-titanium thin-walled tube; it can form a real-time closed-loop adjustment mechanism based on forming parameters such as temperature rise, resistance change rate, and roundness deviation, synchronously adjusting the pulse current and ultrasonic vibration used for forming medical nickel-titanium micro-thin-walled tubes, so that the forming parameters generated during the forming process are always maintained within the preset range, thereby constructing a synergistic precision forming system for the thermal, mechanical, and phase transformation coupling characteristics of medical nickel-titanium materials, so that the forming result of medical nickel-titanium micro-thin-walled tubes can take into account geometric accuracy, surface integrity, and functional consistency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for forming a nickel-titanium thin-walled tube in one embodiment;

[0020] Figure 2 This is a schematic diagram of the process of applying pulsed current and ultrasonic vibration in one embodiment;

[0021] Figure 3 This is a schematic diagram of the forming system for a nickel-titanium thin-walled tube in one embodiment;

[0022] Figure 4 This is a schematic flowchart of a low-damage precision forming method for medical nickel-titanium micro-thin-walled tubes in one embodiment;

[0023] Figure 5 This is a schematic diagram of a partitioned stiffness inner support mandrel inserted into the inner cavity of a medical nickel-titanium micro-thin-walled tube in one embodiment;

[0024] Figure 6 This is a schematic diagram of applying pulsed current and ultrasonic vibration in one embodiment;

[0025] Figure 7This is a schematic flowchart of a method for forming a nickel-titanium thin-walled tube in another embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0028] Traditional multi-pass plastic forming processes for manufacturing medical nickel-titanium tubing typically use nickel-titanium alloy billets as raw materials. These billets undergo multiple drawing, diameter reduction, annealing, straightening, and finishing processes to obtain the target specifications. The tubing is then used for subsequent laser cutting, heat setting, and surface treatment to fabricate vascular stents, filters, or other interventional implantable devices. While this process enables the basic dimensional forming and subsequent processing of medical nickel-titanium tubing, its primary focus is on achieving the correct tubing dimensions and the feasibility of subsequent device fabrication. However, it lacks targeted and coordinated control measures for issues that easily arise during the forming process of medical nickel-titanium micro-thin-walled tubing, such as localized out-of-roundness and collapse, uneven wall thickness, accumulated surface damage, and phase transformation-related performance fluctuations. Specifically, during forming, the tubing is prone to out-of-roundness, localized collapse, and uneven wall thickness, resulting in poor dimensional consistency. Secondly, due to significant friction at the forming interface, surface scratches, deepening of defect layers, and even microcrack initiation are easily generated, affecting subsequent fatigue performance and durability. Third, nickel-titanium materials are highly sensitive to thermal and stress history. In traditional processes, localized stress and temperature rise are difficult to control precisely, which can easily lead to fluctuations in phase transformation-related properties, fluctuations in recovery behavior, and a decrease in batch-to-batch stability. Fourth, existing processes rely heavily on empirical parameter settings and lack real-time feedback and closed-loop adjustment methods for the forming process, making it difficult to simultaneously and stably control forming load, surface quality, dimensional accuracy, and functional performance. Most importantly, traditional technologies cannot effectively control cross-sectional instability, surface damage, and phase transformation-related property fluctuations simultaneously during the forming process of medical nickel-titanium micro-thin-walled tubes, making it difficult to obtain forming results that combine high geometric accuracy, high surface integrity, and high functional consistency.

[0029] Based on the aforementioned traditional technologies, this application provides a method for forming nickel-titanium thin-walled tubes. During the forming process of the nickel-titanium thin-walled tube to be formed, an auxiliary forming method is used to perform auxiliary forming treatment on the tube, and the forming parameters of the nickel-titanium thin-walled tube are determined. The auxiliary forming method includes at least one of pulse current-assisted forming and ultrasonic vibration-assisted forming. The auxiliary forming method is adjusted according to the forming parameters so that the forming parameters corresponding to the adjusted auxiliary forming method are within a preset forming parameter range. The nickel-titanium thin-walled tube is then subjected to auxiliary forming treatment according to the adjusted auxiliary forming method to obtain the formed nickel-titanium thin-walled tube. A real-time closed-loop adjustment mechanism based on forming parameters such as temperature rise, resistance change rate, and roundness deviation can be formed. The pulse current and ultrasonic vibration used for forming the medical nickel-titanium micro-thin-walled tube are simultaneously adjusted, ensuring that the forming parameters generated during the forming process are always maintained within a preset range. This constructs a collaborative precision forming system targeting the thermal, mechanical, and phase transformation coupling characteristics of medical nickel-titanium materials, enabling the forming result of the medical nickel-titanium micro-thin-walled tube to balance geometric accuracy, surface integrity, and functional consistency.

[0030] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0031] In one exemplary embodiment, such as Figure 1 As shown, a method for forming a nickel-titanium thin-walled tube is provided. This embodiment illustrates the application of this method to a control device, wherein the control device includes, but is not limited to, various controllers, terminals, servers, etc., and is not limited thereto. In this embodiment, the method includes the following steps:

[0032] Step S102: During the forming process of the nickel-titanium thin-walled tube to be formed, the nickel-titanium thin-walled tube is subjected to auxiliary forming process according to the auxiliary forming method, and the forming parameters of the nickel-titanium thin-walled tube are determined; the auxiliary forming method includes at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method.

[0033] The nickel-titanium thin-walled tube can be, but is not limited to, various medical-grade nickel-titanium micro-thin-walled tubes. Assisted forming methods refer to the precise shaping of the nickel-titanium thin-walled tube using current, ultrasound, or other methods in synergy after it enters the effective loading range of the mold. Pulse current assisted forming can be a method of applying segmented triggered pulsed currents to the nickel-titanium thin-walled tube and the mold to limit local heat input and reduce instantaneous deformation resistance. Ultrasonic vibration can be an auxiliary forming method that applies ultrasonic vibration at the contact interface between the nickel-titanium thin-walled tube and the mold, and / or at the contact interface between the nickel-titanium thin-walled tube and the mandrel, to reduce interface friction and mitigate surface scratches. Forming parameters can be relevant parameters of the nickel-titanium thin-walled tube collected in real time during the forming process, including but not limited to temperature rise, resistance change rate, roundness deviation, wall thickness deviation, and surface defects.

[0034] Optionally, a mandrel can be inserted into the cavity of the nickel-titanium thin-walled tube, and a mold can be set outside the nickel-titanium thin-walled tube. During the forming process, the mandrel can be used to support the nickel-titanium thin-walled tube, and the mold can define the outer contour of the nickel-titanium thin-walled tube. The control device can perform auxiliary forming treatment on the nickel-titanium thin-walled tube to be formed based on pulse current and ultrasonic vibration, including applying pulse current to the nickel-titanium thin-walled tube and the mold, and applying ultrasonic vibration at the contact interface between the nickel-titanium thin-walled tube and the mold, and / or at the contact interface between the nickel-titanium thin-walled tube and the mandrel. The control device can collect the forming parameters of the nickel-titanium thin-walled tube in real time.

[0035] In practical applications, a partitioned stiffness internal support mandrel can be inserted into the inner cavity of a medical nickel-titanium micro-thin-walled tube. This partitioned stiffness internal support mandrel can be a built-in mandrel component that is divided into different stiffness sections along the axial direction, relying on a differentiated stiffness structure to support the inner wall of the nickel-titanium micro-thin-walled tube. On the partitioned stiffness internal support mandrel, the mandrel section corresponding to the formed area of ​​the nickel-titanium micro-thin-walled tube is a high-stiffness support section, meaning it has high stiffness and strength and can stably support the tube wall. The mandrel section corresponding to the non-formed transition area of ​​the nickel-titanium micro-thin-walled tube is a retractable transition section, meaning it has self-adaptive retraction capability, can adapt to tube deformation and displacement, and avoids damage to the tube from compression or impact. A mold is set on the outside of the medical nickel-titanium micro-thin-walled tube. The medical nickel-titanium micro-thin-walled tube is formed by diameter reduction and / or rounding in a segmented small deformation progressive manner. Specifically, the medical nickel-titanium micro-thin-walled tube can be divided into multiple forming zones. Only when the forming zone enters the effective loading zone of the mold, a segmented trigger pulse current is applied to the tube and the mold to limit local heat input and reduce instantaneous deformation resistance. At the same time, ultrasonic vibration can be applied at the contact interface between the tube and the mold and / or mandrel in the forming zone to reduce interface friction and reduce surface scratches. During the forming process, forming parameters such as temperature rise, resistance change rate, roundness deviation, wall thickness deviation, and surface defects in the forming zone can be collected in real time.

[0036] Step S104: Adjust the auxiliary forming method according to the forming parameters so that the forming parameters corresponding to the adjusted auxiliary forming method are within the preset forming parameter range.

[0037] The preset forming parameter range refers to the range of values ​​for the forming parameters that are set in advance.

[0038] Optionally, the control device can adjust at least one of the pulse current-assisted forming method and the ultrasonic vibration-assisted forming method based on the real-time collected forming parameters of the nickel-titanium thin-walled tube, so that the nickel-titanium thin-walled tube is assisted in forming according to the adjusted auxiliary forming method, and the corresponding forming parameters are within the preset forming parameter range. In practical applications, the peak value of the pulse current, the pulse duration, the ultrasonic amplitude, and the feed speed can be adjusted synchronously based on the forming parameters such as the temperature rise, resistance change rate, roundness deviation, wall thickness deviation, and surface defects of the forming area collected in real time during the forming process, so that each forming parameter is always maintained within the preset control window during the forming process. In some embodiments, when the temperature rise of the forming area of ​​the medical nickel-titanium micro-thin-walled tube is detected to be close to the local temperature rise limit, the peak value of the pulse current can be reduced and / or the pulse duration can be shortened. In other embodiments, when the roundness deviation of the forming area of ​​the medical nickel-titanium micro-thin-walled tube is detected to be increasing, the ultrasonic amplitude and feed speed can be appropriately adjusted (e.g., reduced) to reduce local friction and uneven deformation. In some other embodiments, when an abnormal rate of change in resistivity of the forming region of the medical nickel-titanium micro-thin-walled tube is detected (e.g., higher than the upper limit or lower than the lower limit), it can be determined that the material state of the forming region has deviated, and the heat input and feed rate can be corrected simultaneously. Through the closed-loop adjustment of the above three parameters, the entire forming process can be kept within the preset control window.

[0039] Step S106: According to the adjusted auxiliary forming method, the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment to obtain the formed nickel-titanium thin-walled tube.

[0040] Optionally, the control device can perform assisted forming processing on the nickel-titanium thin-walled tube according to at least one of the adjusted pulse current assisted forming method and the adjusted ultrasonic vibration assisted forming method to obtain the formed nickel-titanium thin-walled tube. In practical applications, for multiple forming areas of the medical nickel-titanium micro-thin-walled tube, after synchronously adjusting the pulse current peak value, pulse duration, ultrasonic amplitude, and feed speed according to the forming parameters such as real-time collected temperature rise, resistance change rate, roundness deviation, wall thickness deviation, and surface defects, the current forming area of ​​the medical nickel-titanium micro-thin-walled tube can be assisted in forming based on the adjusted pulse current and / or adjusted ultrasonic vibration, and the next forming area of ​​the medical nickel-titanium micro-thin-walled tube can also be assisted in forming, without limitation.

[0041] The aforementioned method for forming nickel-titanium thin-walled tubes involves assisting in the forming process of the nickel-titanium thin-walled tube according to an auxiliary forming method, determining the forming parameters of the nickel-titanium thin-walled tube, and determining at least one of pulsed current-assisted forming and ultrasonic vibration-assisted forming methods. The auxiliary forming method is adjusted according to the forming parameters to ensure that the forming parameters corresponding to the adjusted auxiliary forming method are within a preset forming parameter range. The nickel-titanium thin-walled tube is then subjected to auxiliary forming according to the adjusted auxiliary forming method to obtain the formed nickel-titanium thin-walled tube. A real-time closed-loop adjustment mechanism based on forming parameters such as temperature rise, resistance change rate, and roundness deviation can be established, synchronously adjusting the pulsed current and ultrasonic vibration used for forming the medical nickel-titanium micro-thin-walled tube. This ensures that the forming parameters generated during the forming process are always maintained within a preset range, thereby constructing a collaborative precision forming system targeting the thermal, mechanical, and phase transformation coupling characteristics of medical nickel-titanium materials. This allows the forming result of the medical nickel-titanium micro-thin-walled tube to balance geometric accuracy, surface integrity, and functional consistency.

[0042] In an exemplary embodiment, the nickel-titanium thin-walled tube is provided with multiple forming zones along the axial direction; the above step S102 may specifically include: controlling the nickel-titanium thin-walled tube to advance along the axial direction; performing auxiliary forming processing on each forming zone of the nickel-titanium thin-walled tube according to the auxiliary forming method; the deformation amount of each forming zone does not exceed a preset threshold, and the auxiliary forming processing includes at least one of diameter reduction forming processing and rounding forming processing.

[0043] The forming zone refers to the area of ​​the nickel-titanium thin-walled tube wall where radial deformation and changes in size and contour occur due to the action of the mold and mandrel. Deformation amount refers to the maximum degree of deformation in the forming zone. The preset threshold refers to the pre-set upper limit of the deformation amount. Diameter reduction forming is a processing step that uses the extrusion action of a mold to reduce the diameter of the nickel-titanium thin-walled tube, causing the tube to radially shrink to the target outer diameter. Rounding forming is a shaping process that corrects tube deformation defects, straightens irregular cross-sections, restores a standard circular contour, and improves roundness accuracy.

[0044] Optionally, the nickel-titanium thin-walled tube can be provided with multiple forming zones along the axial direction. During the forming process, the control equipment can control the nickel-titanium thin-walled tube to move forward along the axial direction, and perform auxiliary forming for each forming zone of the nickel-titanium thin-walled tube based on pulse current assisted forming and / or ultrasonic vibration assisted forming, including diameter reduction forming and / or rounding forming, and the deformation of each forming zone after forming does not exceed a preset threshold. In practical applications, a segmented small deformation progressive method can be adopted, using a progressive forming module to perform diameter reduction forming and / or rounding forming of medical nickel-titanium micro-thin-walled tubes. The segmented small deformation progressive method refers to the processing mode of breaking down the overall deformation of the tube into multiple segments for sequential processing, applying only a small amount of deformation at a time, and gradually completing the overall forming. Specifically, multiple forming segments can be continuously arranged along the tube axis, and each forming segment has a preset small deformation amount to avoid local instability, sudden changes in wall thickness, or springback fluctuations caused by excessive deformation at a time. The tube can move forward along the axis under the drive of the feeding mechanism, passing through multiple effective loading areas of the molds in sequence. Each time it passes through a forming segment, a small diameter reduction or rounding is completed. The deformation amount of a single segment can account for 5% to 40% of the target total deformation amount, preferably 10% to 25%.

[0045] In this embodiment, by controlling the nickel-titanium thin-walled tube to advance along the axial direction and performing auxiliary forming treatment on each forming area of ​​the nickel-titanium thin-walled tube according to the auxiliary forming method, it is possible to avoid local instability, sudden changes in wall thickness or rebound fluctuations caused by excessive deformation in a single operation, thereby improving the geometric accuracy of forming medical nickel-titanium micro-thin-walled tubes.

[0046] In one exemplary embodiment, such as Figure 2 As shown, the above-mentioned auxiliary forming process for each forming area of ​​the nickel-titanium thin-walled tube, according to the auxiliary forming method, can specifically include:

[0047] Step S201: Apply pulsed current to the forming area and the mold according to the pulsed current assisted forming method;

[0048] In step S202, ultrasonic vibration is applied at the contact interface between the forming area and the mold, and / or at the contact interface between the forming area and the mandrel, according to the ultrasonic vibration-assisted forming method; the mold is placed on the outside of the nickel-titanium thin-walled tube, and the mandrel is placed inside the cavity of the nickel-titanium thin-walled tube.

[0049] Among them, pulsed current refers to segmented intermittent current. Ultrasonic vibration refers to high-frequency vibration caused by ultrasound.

[0050] Optionally, during the forming process, the control equipment can apply pulsed current to the forming area of ​​the nickel-titanium thin-walled tube and the mold in a pulsed current assisted forming mode to limit local heat input and reduce instantaneous deformation resistance. Alternatively, it can apply ultrasonic vibration at the contact interface between the forming area of ​​the nickel-titanium thin-walled tube and the mold, and / or at the contact interface between the forming area of ​​the nickel-titanium thin-walled tube and the mandrel in an ultrasonic vibration assisted forming mode to reduce friction at the contact interface and reduce surface scratches.

[0051] In this embodiment, by applying pulsed current to the forming area and the mold according to the pulsed current assisted forming method, and by applying ultrasonic vibration assisted forming method to the contact interface between the forming area and the mold, and / or the contact interface between the forming area and the mandrel, segmented trigger pulsed current can be applied when the forming area enters the effective loading area of ​​the mold, so as to reduce the instantaneous deformation resistance while limiting the local heat input, and avoid causing excessive disturbance to the nickel-titanium phase transformation performance. At the same time, the ultrasonic vibration friction reduction mechanism introduced at the forming contact interface also reduces interface friction and surface scratches.

[0052] In an exemplary embodiment, the forming area corresponds to the effective loading area of ​​the mold; the above step S201 may specifically include: triggering a loading pulse current when the forming area enters the effective loading area; and stopping the loading pulse current when the forming area leaves the effective loading area.

[0053] The effective loading zone refers to the effective area where the mold contacts the pipe and can apply forming force to cause the pipe to deform.

[0054] Optionally, the forming zone of the nickel-titanium thin-walled tube can correspond to the effective loading zone on the mold, so that a forming force is applied to the forming zone through the effective loading zone. During the axial advancement of the nickel-titanium thin-walled tube, the control device can trigger a loading pulse current when the forming zone of the nickel-titanium thin-walled tube enters the effective loading zone of the mold, and stop the loading pulse current when the forming zone of the nickel-titanium thin-walled tube leaves the effective loading zone of the mold. In practical applications, for each forming segment of the segmented small deformation progressive method, a segmented trigger pulse current can be applied to the forming zone and the mold only when the forming zone of the tube enters the effective loading zone of the mold. The peak current of the segmented trigger pulse current can be 0.5A to 500A, preferably 100A to 400A; the duration of a single pulse can be 0.1ms to 500ms, preferably 1ms to 100ms; the pulse duty cycle can be 1% to 60%, preferably 5% to 30%; and the pulse frequency can be 0.1Hz to 10000Hz, preferably 1Hz to 2000Hz. The pulsed current can be triggered only when the forming zone enters the effective loading zone of the mold, and the loading can be stopped after the forming zone leaves the effective loading zone of the mold.

[0055] In this embodiment, by triggering a loading pulse current when the forming area enters the effective loading area and stopping the loading pulse current when the forming area leaves the effective loading area, the heat input can be concentrated only in the local area where the actual deformation occurs, and the heat input time is strictly controlled.

[0056] In an exemplary embodiment, step S202 may specifically include: loading ultrasonic vibration according to a preset timing sequence so that the ultrasonic vibration is coupled with the pulsed current.

[0057] Among them, the preset timing sequence refers to the pre-set timing sequence of ultrasonic vibration loading. Coupling refers to the timing matching and operational linkage between ultrasonic vibration and pulse current, which jointly assists in pipe forming.

[0058] Optionally, the control device can apply ultrasonic vibration intermittently according to a preset timing sequence, coupling the ultrasonic vibration with pulsed current. This primarily acts on the stage where the nickel-titanium thin-walled tube forming area contacts the mold and / or mandrel during the forming process—the forming contact stage. In practical applications, for each forming segment in the segmented small deformation progressive method, ultrasonic vibration can be applied only at the interface between the tube and the mold and / or mandrel in the forming area to reduce interface friction, mitigate surface scratches and wear, and improve the uniformity of material flow within the forming area. The frequency of the ultrasonic vibration can be 15kHz to 80kHz, preferably 20kHz to 60kHz; the amplitude can be 1μm to 100μm, preferably 5μm to 50μm; the ultrasonic vibration loading time can be 1ms to 1000ms, preferably 10ms to 300ms; and the ultrasonic vibration can be continuous or intermittent, preferably intermittent. In some embodiments, ultrasonic vibration can be applied to the mandrel end and transmitted to the contact interface of the forming area. The ultrasonic vibration can be applied intermittently and coupled with the pulse current in a preset time sequence, so that the ultrasonic vibration mainly acts on the forming contact stage.

[0059] In this embodiment, by loading ultrasonic vibration according to a preset timing sequence, the ultrasonic vibration is coupled with the pulse current, which can reduce the friction at the contact interface between the nickel-titanium thin-walled tube and the mold or mandrel, and reduce surface scratches and wear of the nickel-titanium thin-walled tube.

[0060] In an exemplary embodiment, the forming parameters include at least the temperature rise value, resistance change rate, and deformation deviation of the nickel-titanium thin-walled tube, wherein the deformation deviation includes at least one of roundness deviation and wall thickness deviation; step S104 above may include at least one of the following: adjusting the peak value of the pulse current and / or the pulse duration according to the temperature rise value; adjusting the ultrasonic amplitude and / or the feed speed according to the deformation deviation; and adjusting at least one of the peak value of the pulse current, the pulse duration, the ultrasonic amplitude, and the feed speed according to the resistance change rate.

[0061] Among these, temperature rise refers to the increase in temperature in the forming zone of the nickel-titanium thin-walled tube relative to the ambient temperature before forming. Resistance change rate refers to the rate of change of real-time resistance value relative to the initial resistance value during the forming process. Deformation deviation includes roundness deviation and wall thickness deviation. Roundness deviation refers to the difference between the maximum and minimum outer diameters of the same cross-section, while wall thickness deviation refers to the difference between the maximum and minimum wall thicknesses at different circumferential positions of the same cross-section, or the deviation relative to the target wall thickness. Pulse current peak value refers to the maximum instantaneous current value achievable by a single pulse current. Pulse duration refers to the effective duration of a single pulse current from conduction to disconnection. Ultrasonic amplitude refers to the maximum displacement amplitude of the ultrasonic reciprocating motion, reflecting the intensity of the vibration. Feed rate refers to the travel speed of the nickel-titanium thin-walled tube.

[0062] Optionally, the control device can adjust the pulse current-assisted forming method and / or ultrasonic vibration-assisted forming method based on the forming parameters of the nickel-titanium thin-walled tube forming area obtained by real-time measurement. This includes adjusting the pulse current peak value and / or pulse duration based on the temperature rise value, adjusting the ultrasonic amplitude and / or feed speed based on the roundness deviation and / or wall thickness deviation, and adjusting the pulse current peak value, pulse duration, ultrasonic amplitude, and / or feed speed based on the resistance change rate. For example, when the temperature rise in the forming area of ​​the medical nickel-titanium micro-thin-walled tube is detected to be close to the upper limit of the local temperature rise, the pulse current peak value can be reduced and / or the pulse duration shortened; when the roundness deviation in the forming area of ​​the medical nickel-titanium micro-thin-walled tube is detected to be increasing, the ultrasonic amplitude and feed speed can be appropriately adjusted (e.g., reduced) to reduce local friction and uneven deformation; when the resistance change rate in the forming area of ​​the medical nickel-titanium micro-thin-walled tube is detected to be abnormal (e.g., higher than the upper limit or lower than the lower limit), it can be determined that the material state of the forming area has deviated, and the heat input and feed speed can be corrected simultaneously. By adjusting the above three parameters in a closed loop, the entire forming process can be kept within the preset control window.

[0063] In this embodiment, by adjusting the peak value of the pulse current and / or the pulse duration according to the temperature rise value, adjusting the ultrasonic amplitude and / or the feed speed according to the deformation deviation, and adjusting at least one of the peak value of the pulse current, the pulse duration, the ultrasonic amplitude, and the feed speed according to the resistance change rate, a real-time closed-loop adjustment mechanism based on temperature, resistance change rate, and roundness parameters can be established. The pulse current, ultrasonic vibration, and feed parameters are adjusted synchronously to ensure that the forming process is always maintained within the preset control window.

[0064] In an exemplary embodiment, step S106 may specifically include: performing auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method to obtain a pre-formed nickel-titanium thin-walled tube; and performing stress-relieving heat treatment and electrochemical polishing treatment on the pre-formed nickel-titanium thin-walled tube to obtain a formed nickel-titanium thin-walled tube.

[0065] Optionally, the control equipment can perform auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method to obtain a pre-formed nickel-titanium thin-walled tube. The pre-formed nickel-titanium thin-walled tube can then undergo stress-relief heat treatment to release some of the residual stress introduced during the forming process, followed by electrochemical polishing to reduce the depth of surface defects and improve surface integrity, thus obtaining the formed nickel-titanium thin-walled tube. In practical applications, after forming, the medical nickel-titanium micro-thin-walled tube can undergo short-term stress-relief heat treatment to release some of the residual stress introduced during the forming process, followed by electrochemical polishing to reduce the depth of surface defects and improve surface integrity. The stress-relief heat treatment temperature can be 250℃~550℃, preferably 300℃~450℃, and the stress-relief heat treatment time can be 10s~60min, preferably 30s~20min. The stress-relief heat treatment can be carried out in a protective atmosphere, vacuum environment or inert atmosphere. The electrochemical polishing time can be 5s~30min, preferably 30s~10min, and the electrochemical polishing voltage can be 1V~50V, preferably 3V~20V. After electrochemical polishing, the surface roughness and defect depth of the pipe are further reduced.

[0066] In this embodiment, the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment according to the adjusted auxiliary forming method to obtain a preliminary nickel-titanium thin-walled tube. The preliminary nickel-titanium thin-walled tube is then subjected to stress-relieving heat treatment and electrochemical polishing treatment to obtain a finished nickel-titanium thin-walled tube, which can reduce the surface roughness and defect depth of the tube.

[0067] In one exemplary embodiment, such as Figure 3 As shown, a forming system for a nickel-titanium thin-walled tube is provided, including a controller 302, a mold 304, and a mandrel 306; the mold 304 is placed on the outside of the nickel-titanium thin-walled tube to be formed, and is used to define the outer contour of the nickel-titanium thin-walled tube; the mandrel 306 is placed inside the cavity of the nickel-titanium thin-walled tube, and is used to support the nickel-titanium thin-walled tube; the controller 302 is used to execute the steps of the forming method of the nickel-titanium thin-walled tube in the foregoing embodiments.

[0068] The controller can be, but is not limited to, various central processing units, signal processors, programmable logic devices, artificial intelligence processors, chips, terminals, servers, etc. The mold can be, but is not limited to, various external forming components. The mandrel can be, but is not limited to, various internal support components.

[0069] Optionally, during the forming process, the controller can perform auxiliary forming treatment on the nickel-titanium thin-walled tube to be formed based on pulsed current and ultrasonic vibration, including applying pulsed current to the nickel-titanium thin-walled tube and the mold, and applying ultrasonic vibration at the contact interface between the nickel-titanium thin-walled tube and the mold and / or the mandrel. The controller can collect the forming parameters of the nickel-titanium thin-walled tube in real time, and adjust the pulsed current assisted forming method and / or ultrasonic vibration assisted forming method according to the forming parameters, so that the nickel-titanium thin-walled tube is assisted in forming according to the adjusted auxiliary forming method. The corresponding forming parameters are within the preset forming parameter range. The controller can perform auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted pulsed current assisted forming method and / or the adjusted ultrasonic vibration assisted forming method, including applying the adjusted pulsed current to the nickel-titanium thin-walled tube, and applying the adjusted ultrasonic vibration at the contact interface between the nickel-titanium thin-walled tube and the mold and / or the mandrel, thereby obtaining the formed nickel-titanium thin-walled tube.

[0070] Since the specific processing procedures for the controller, mold, and mandrel have been described in detail in the foregoing embodiments, they will not be repeated here.

[0071] The aforementioned nickel-titanium thin-walled tube forming system, during the forming process of the nickel-titanium thin-walled tube to be formed, performs auxiliary forming treatment according to an auxiliary forming method, and determines the forming parameters of the nickel-titanium thin-walled tube. The auxiliary forming method includes at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method. The auxiliary forming method is adjusted according to the forming parameters so that the forming parameters corresponding to the adjusted auxiliary forming method are within the preset forming parameter range. The nickel-titanium thin-walled tube is then subjected to auxiliary forming treatment according to the adjusted auxiliary forming method to obtain the formed nickel-titanium thin-walled tube. A real-time closed-loop adjustment mechanism based on forming parameters such as temperature rise, resistance change rate, and roundness deviation can be formed. The pulse current and ultrasonic vibration used for forming medical nickel-titanium micro-thin-walled tubes are adjusted synchronously to keep the forming parameters generated during the forming process within the preset range. This constructs a collaborative precision forming system for the thermal, mechanical, and phase transformation coupling characteristics of medical nickel-titanium materials, so that the forming result of medical nickel-titanium micro-thin-walled tubes can take into account geometric accuracy, surface integrity, and functional consistency.

[0072] In an exemplary embodiment, the mandrel includes a supportable stiffness section and a retractable transition section. The supportable stiffness section corresponds to the forming area of ​​the nickel-titanium thin-walled tube and the effective loading area of ​​the mold, and the retractable transition section is located on both sides of the supportable stiffness section.

[0073] The supportable stiffness section refers to the section of the mandrel that is highly rigid and can stably support the tube wall, ensuring the accuracy of the forming dimensions and wall thickness. The yieldable transition section refers to the section of the mandrel that can adaptively shift and buffer, avoiding compression damage to the tube.

[0074] Optionally, a partitioned stiffness inner support mandrel can be inserted into the inner cavity of the medical nickel-titanium micro-thin-walled tube. The partitioned stiffness inner support mandrel can be provided with a support stiffness section and a retractable transition section along the axial direction. The support stiffness section corresponds to the forming area of ​​the medical nickel-titanium micro-thin-walled tube and is used to support the inner wall of the tube during the forming process, suppressing ellipticization and local collapse. The retractable transition section is located on both sides of the support stiffness section and corresponds to the non-forming area or the transition part of the medical nickel-titanium micro-thin-walled tube to be formed. It is used to reduce the mandrel pushing resistance and reduce the additional stress during the axial movement of the tube.

[0075] In this embodiment, the mandrel includes a supportable stiffness section and a retractable transition section. The supportable stiffness section corresponds to the forming area of ​​the nickel-titanium thin-walled tube and the effective loading area of ​​the mold. The retractable transition section is located on both sides of the supportable stiffness section. The supportable stiffness section can support the inner wall of the tube during the forming process, suppressing ellipticization and local collapse. The retractable transition section reduces the mandrel pushing resistance and alleviates the additional stress during the axial movement of the tube.

[0076] To facilitate a deeper understanding of the embodiments of this application by those skilled in the art, a specific example will be used for illustration below.

[0077] To address the problem that traditional technologies struggle to achieve forming results that combine high geometric accuracy, high surface integrity, and high functional consistency, this application designs geometric control, surface damage control, and phase transformation performance stability control in the forming of medical nickel-titanium micro-thin-walled tubes as a holistic technical objective. Specifically, firstly, this application does not simply employ conventional mandrel support, but instead uses a partitioned stiffness internal support mandrel to provide high-rigidity support in the forming zone and retractable support in the transition zone, thereby simultaneously suppressing out-of-roundness collapse and reducing propulsion resistance. Secondly, this application does not use continuous heating or ordinary thermoforming, but applies segmented triggered pulse current only when the forming zone enters the effective loading zone of the mold, thereby limiting local heat input while reducing instantaneous deformation resistance and avoiding excessive disturbance to the nickel-titanium phase transformation properties. Thirdly, this application introduces an ultrasonic vibration friction reduction mechanism at the forming contact interface to reduce interface friction and surface scratches, and improve material flow uniformity. Finally, this application does not simply superimpose the above methods, but further establishes a real-time closed-loop adjustment mechanism based on temperature, resistivity change rate, and roundness parameters, synchronously adjusting the pulse current, ultrasonic vibration, and feed parameters to keep the forming process within a preset control window. In summary, this application constructs a synergistic precision forming system for the thermal, mechanical, and phase transformation coupling characteristics of medical nickel-titanium materials, thereby solving the problem that traditional technologies struggle to simultaneously achieve geometric accuracy, surface integrity, and functional consistency.

[0078] In one exemplary embodiment, a low-damage precision forming method for medical nickel-titanium micro-thin-walled tubes is provided, the method comprising the following steps:

[0079] Step 1: Provide medical nickel-titanium micro-thin-walled tubes with an outer diameter of 0.30mm to 10.00mm and a wall thickness of 0.03mm to 0.50mm;

[0080] Step 2: Insert the partitioned stiffness inner support mandrel into the inner cavity of the medical nickel-titanium micro thin-walled tube. The mandrel section corresponding to the forming area is the high support stiffness section, and the mandrel section corresponding to the non-forming transition area is the retractable transition section.

[0081] Step 3: The medical nickel-titanium micro-thin-walled tube is subjected to diameter reduction forming and / or rounding forming using a segmented small deformation progressive method.

[0082] Step 4: Within each forming section, only when the forming area of ​​the tube enters the effective loading area of ​​the mold, a segmented trigger pulse current is applied to the forming area to limit local heat input and reduce instantaneous deformation resistance.

[0083] Step 5: Apply ultrasonic vibration at the interface between the tube and the mold and / or mandrel in the forming area to reduce interface friction and mitigate surface scratches.

[0084] Step 6: During the forming process, the temperature, resistance change rate and roundness parameters of the forming area are collected in real time, and the peak value of the pulse current, pulse duration, ultrasonic amplitude and feed speed are adjusted synchronously according to the collection results to keep the forming process within the preset control window.

[0085] Step 7: After the forming is completed, the medical nickel-titanium micro-thin-walled tube is subjected to stress-relieving heat treatment and electrochemical polishing treatment.

[0086] The preset control window includes at least the local temperature rise limit, roundness deviation limit, wall thickness deviation limit, and allowable offset range of phase change related parameters;

[0087] Furthermore, the synergistic effects of the partitioned stiffness inner support mandrel, segmented trigger pulse current, ultrasonic vibration, and synchronous adjustment ensure that the roundness deviation, wall thickness deviation, and phase transformation related parameter offset of the formed medical nickel-titanium micro-thin-walled tube are all within the preset control window.

[0088] In an exemplary embodiment, each forming segment in step S3 above has a preset small deformation amount, and adjacent forming segments are arranged continuously along the axial direction of the pipe.

[0089] In an exemplary embodiment, the high-stiffness section of the partitioned stiffness inner support mandrel is used to suppress ellipticization and local collapse of the forming zone, and the collapsible transition section is used to reduce the axial propulsion resistance of the tube.

[0090] In an exemplary embodiment, the segmented trigger pulse current in step S4 above is a low duty cycle pulse current.

[0091] In an exemplary embodiment, the pulse current in step S4 above stops loading after the forming zone leaves the effective loading zone of the mold.

[0092] In an exemplary embodiment, the ultrasonic vibration in step S5 above is applied to the mold end, the mandrel end, or both the mold end and the mandrel end.

[0093] In an exemplary embodiment, the ultrasonic vibration in step S5 is intermittently applied and coupled with the segmented trigger pulse current in step S4 according to a preset timing sequence.

[0094] In an exemplary embodiment, step S6 above also collects the forming load and / or springback amount, and uses them as auxiliary feedback parameters for synchronous adjustment.

[0095] In an exemplary embodiment, the synchronization adjustment in step S6 above includes simultaneously adjusting the peak pulse current, pulse duration, ultrasonic amplitude, and feed rate.

[0096] In an exemplary embodiment, the stress-relieving heat treatment in step S7 above is a short-time stress-relieving heat treatment.

[0097] In an exemplary embodiment, the electrochemical polishing process in step S7 above is used to reduce the depth of defects on the formed surface and improve surface integrity.

[0098] In an exemplary embodiment, the allowable offset range of the phase change related parameters is such that the change in phase change related characteristic parameters after forming is within a preset window relative to before forming.

[0099] In an exemplary embodiment, the formed medical nickel-titanium micro-thin-walled tube is used to fabricate vascular stents, thrombectomy stents, filters, valve support structures, or delivery system reinforcement tubes, for example, for subsequent laser cutting to form vascular stents, thrombectomy stents, filters, valve support structures, or delivery system reinforcement tubes.

[0100] In one exemplary embodiment, such as Figure 4 As shown, a low-damage precision forming method for medical nickel-titanium micro-thin-walled tubes is provided, which specifically includes the following steps:

[0101] Step S401, raw material preparation.

[0102] refer to Figure 5Medical-grade nickel-titanium micro-thin-walled tube 501 was selected as the material to be formed. The outer diameter of the medical-grade nickel-titanium micro-thin-walled tube can be 0.30mm to 10.00mm, preferably 0.50mm to 5.00mm, and in this embodiment, it is 3.00mm. The wall thickness of the medical-grade nickel-titanium micro-thin-walled tube can be 0.03mm to 0.30mm, preferably 0.05mm to 0.30mm, and in this embodiment, it is 0.20mm. The tube length can be 100mm to 2000mm, preferably 200mm to 1500mm, and in this embodiment, it is 1000mm. The tube to be formed is then degreased, cleaned, ultrasonically rinsed, and dried before use.

[0103] Step S402: Set the partition stiffness inner support mandrel.

[0104] A partitioned stiffness inner support mandrel is inserted into the inner cavity of a medical nickel-titanium micro-thin-walled tube. The partitioned stiffness inner support mandrel is axially configured with a high-stiffness section 502 and a retractable transition section 503. The high-stiffness section 502 corresponds to the forming zone and is used to support the inner wall of the tube during forming, suppressing ellipticization and local collapse. The retractable transition section 503 corresponds to the non-forming zone or the transition area to the forming zone, and is used to reduce the mandrel's pushing resistance and alleviate additional stress during the axial movement of the tube. The axial length of the high-stiffness section can be 2mm to 50mm, preferably 5mm to 20mm, and is 10mm in this embodiment. The axial length of the retractable transition section can be 1mm to 30mm, preferably 3mm to 15mm, and is 6mm in this embodiment.

[0105] In this embodiment, the high-stiffness support section is positioned at the corresponding location of the effective loading area of ​​the current mold, and the collapsible transition sections are located on its front and rear sides. The radial support capacity of the high-stiffness support section is higher than that of the collapsible transition section. Preferably, the radial compressive deformation of the high-stiffness support section is less than that of the collapsible transition section.

[0106] Step S403: Establish the forming control window.

[0107] Based on the target specifications, a forming control window is pre-defined. The forming control window should include at least the following:

[0108] Based on the target specifications, a forming control window is established before forming. The forming control window includes: local temperature rise in the forming area controlled within 30℃; roundness deviation controlled within 0.010mm; wall thickness deviation controlled within ±8% of the nominal wall thickness; post-forming Af offset controlled within ±5℃; and maximum surface defect depth controlled below 5μm. During forming, temperature, resistivity change rate, and roundness parameters are monitored in real time and compared with the preset control window. When any parameter approaches or exceeds the preset boundary, the pulse current peak value, pulse duration, ultrasonic amplitude, and feed speed are immediately corrected synchronously to bring the forming process back within the control window. All real-time adjustments during forming aim to maintain the detected parameters within the aforementioned control window.

[0109] Step S404: Segmented small deformation progressive forming.

[0110] A progressive forming module is used to perform diameter reduction forming and rounding forming of medical nickel-titanium micro-thin-walled tubes. The forming method involves arranging multiple forming segments continuously along the tube axis, with each forming segment having a preset small deformation amount to avoid local instability, sudden changes in wall thickness, or springback fluctuations caused by excessive deformation in a single step.

[0111] Specifically, the pipe moves forward along the axial direction under the drive of the feeding mechanism and passes through multiple effective loading areas of the mold in sequence. Each time it passes through a forming section, it completes a small reduction in diameter or rounding. The deformation of a single section can account for 5% to 40% of the total target deformation, preferably 10% to 25%, and in this embodiment it is about 15%.

[0112] Step S405: Segmented trigger pulse current loading.

[0113] refer to Figure 6Within each forming section, a segmented trigger pulse current is applied to the forming zone only when the forming zone enters the effective loading zone 504 of the mold. The peak current of the segmented trigger pulse current can be 0.5A to 500A, preferably 100A to 400A, and in this embodiment, it is 300A. The duration of a single pulse can be 0.1ms to 500ms, preferably 1ms to 100ms, and in this embodiment, it is 20ms. The pulse duty cycle can be 1% to 60%, preferably 5% to 30%, and in this embodiment, it is 15%. The pulse frequency can be 0.1Hz to 10000Hz, preferably 1Hz to 2000Hz, and in this embodiment, it is 100Hz. The pulse current triggers loading only when the forming zone enters the effective loading zone of the mold and stops loading after the forming zone leaves the effective loading zone of the mold. The pulse current is used to reduce instantaneous deformation resistance and limit local heat input within a preset control range, avoiding heat accumulation and phase change-related parameter drift caused by continuous overall heating. Once the forming zone leaves the effective loading zone of the mold, the pulsed current stops loading. In this way, heat input is concentrated only in the localized area where deformation actually occurs, and the heat input time is strictly controlled.

[0114] Step S406: Ultrasonic vibration loading of the contact area.

[0115] Ultrasonic vibration 505 is applied at the interface between the tube and the mold and / or mandrel in the forming zone to reduce interface friction, mitigate surface scratches and wear, and improve the uniformity of material flow within the forming zone. The frequency of the ultrasonic vibration can be 15kHz to 80kHz, preferably 20kHz to 60kHz, and in this embodiment, it is 28kHz. The amplitude of the ultrasonic vibration can be 1μm to 100μm, preferably 5μm to 50μm, and in this embodiment, it is 20μm. The ultrasonic vibration loading time can be 1ms to 1000ms, preferably 10ms to 300ms, and in this embodiment, it is 50ms. The ultrasonic vibration can be continuous or intermittent, preferably intermittent; in this embodiment, an intermittent loading method coupled with a pulsed current is used. In this embodiment, the ultrasonic vibration is applied to the mandrel end and transmitted to the contact interface of the forming zone. The ultrasonic vibration is intermittently loaded and coupled with the pulsed current according to a preset timing sequence, so that the ultrasonic vibration mainly acts on the forming contact stage.

[0116] Step S407: Real-time acquisition and synchronous closed-loop adjustment of three parameters.

[0117] During the forming process, the temperature, resistivity change rate, and roundness parameters of the forming zone are collected in real time, and the peak value of the pulse current, pulse duration, ultrasonic amplitude, and feed speed are adjusted synchronously based on the collected results. The upper limit of local temperature rise can be set according to the allowable performance fluctuation range of the nickel-titanium material.

[0118] Preferably, the increase in temperature in the forming zone relative to the ambient temperature before forming is controlled within the range of 350℃ to 650℃, more preferably 400℃ to 5500℃, and in this embodiment, it is controlled within 500℃. The resistance change rate is the rate of change of the real-time resistance value relative to the initial resistance value during the forming process.

[0119] The resistance change rate control window can be pre-calibrated according to the pipe specifications and target process conditions.

[0120] Preferably, when the rate of change of resistance deviates from the preset range, it is determined that the material state of the forming zone has changed, and synchronous correction of the pulse current parameters and feed speed is triggered. The upper limit of roundness deviation can be 0.001mm to 0.100mm, preferably 0.002mm to 0.050mm, and in this embodiment it is controlled within 0.010mm. The upper limit of wall thickness deviation can be 1% to 30% of the nominal wall thickness, preferably 2% to 15%, and in this embodiment it is controlled within ±8%.

[0121] Wall thickness deviation is the difference between the maximum and minimum wall thickness at different circumferential positions of the same cross section, or the deviation value relative to the target wall thickness.

[0122] The roundness deviation is the difference between the maximum and minimum outer diameters of the same cross-section, or a value measured using conventional roundness evaluation methods in the art. Preferably, the phase transformation related parameters are at least one of Af, As, Ms, and Mf, wherein As is the austenitic phase transformation start temperature, Af is the austenitic phase transformation end temperature, Ms is the martensitic phase transformation start temperature, and Mf is the martensitic phase transformation end temperature.

[0123] More preferably, the Af offset after forming is controlled within ±15℃, more preferably within ±10℃, and in this embodiment, within ±5℃. The maximum depth of surface defects on the formed pipe can be controlled within the range of 0.5μm to 50μm, more preferably within the range of 1μm to 20μm, and in this embodiment, less than 5μm.

[0124] Surface defects include scratches, scratches, indentations, surface cracks, or deepening of the defect layer.

[0125] When the temperature rise in the forming zone is detected to be close to the upper limit of the local temperature rise, the peak value of the pulse current is reduced and / or the pulse duration is shortened; when the roundness deviation is detected to be increasing, the ultrasonic amplitude and feed speed are adjusted appropriately to reduce local friction and uneven deformation; when the resistance change rate is detected to be abnormal, it is determined that the material state in the forming zone has deviated, and the heat input and feed parameters are corrected simultaneously.

[0126] By adjusting the above three parameters in a closed loop, the entire forming process is kept within the preset control window.

[0127] Step S408, post-processing.

[0128] After forming, the medical nickel-titanium micro-thin-walled tube undergoes a short-term stress-relieving heat treatment to release some of the residual stress introduced during forming. This is followed by electrochemical polishing to reduce surface defect depth and improve surface integrity. The stress-relieving heat treatment temperature can be 250℃~550℃, preferably 300℃~450℃, and in this embodiment, it is 380℃. The stress-relieving heat treatment time can be 10s~60min, preferably 30s~20min, and in this embodiment, it is 5min. The stress-relieving heat treatment can be performed under a protective atmosphere, vacuum environment, or inert atmosphere. The electrochemical polishing time can be 5s~30min, preferably 30s~10min, and in this embodiment, it is 3min. The electrochemical polishing voltage can be 1V~50V, preferably 3V~20V, and in this embodiment, it is 8V. After electrochemical polishing, the surface roughness and defect depth of the tube are further reduced.

[0129] In the above embodiments, to address the issues of instability, damage, and functional sensitivity during the forming process of medical nickel-titanium micro-thin-walled tubes, a synergistic forming mechanism combining zoned support, locally controlled heat input, contact friction reduction, and multi-parameter closed-loop adjustment was constructed. Through the synergistic effect of these technical solutions, the forming zone achieves reduced instantaneous deformation resistance while its heat input is limited to a localized and controlled range, thus avoiding the heat accumulation effect caused by continuous heating. Under the combined action of internal support and ultrasonic friction reduction, material flow is more uniform, significantly reducing local stress concentration and surface damage. Real-time judgment and dynamic correction of the forming state are achieved through the linkage feedback of temperature, resistivity change rate, and roundness parameters. This not only improves individual performance indicators (such as roundness or surface quality) but also achieves synergistic optimization among geometric accuracy, surface integrity, and phase change functional stability, obtaining comprehensive technical effects that are difficult to achieve simultaneously with existing technologies.

[0130] In one exemplary embodiment, such as Figure 7 As shown, a method for forming a nickel-titanium thin-walled tube is provided, comprising:

[0131] Step S601: During the forming process of the nickel-titanium thin-walled tube to be formed, the nickel-titanium thin-walled tube is controlled to move forward along the axial direction; the nickel-titanium thin-walled tube is provided with multiple forming zones along the axial direction.

[0132] Step S602: Apply pulsed current to the forming area and the mold according to the pulsed current assisted forming method;

[0133] Step S603: Apply ultrasonic vibration at the contact interface between the forming area and the mold and / or mandrel according to the ultrasonic vibration assisted forming method;

[0134] Step S604: Determine the forming parameters of the nickel-titanium thin-walled tube; the forming parameters include at least the temperature rise, resistance change rate, and deformation deviation of the nickel-titanium thin-walled tube.

[0135] Step S605: Adjust the peak value of the pulse current and / or the pulse duration according to the temperature rise value, adjust the ultrasonic amplitude and / or the feed speed according to the deformation deviation, and adjust at least one of the peak value of the pulse current, the pulse duration, the ultrasonic amplitude and the feed speed according to the resistance change rate, so that the forming parameters corresponding to the adjusted auxiliary forming method are within the preset forming parameter range.

[0136] Step S606: According to the adjusted auxiliary forming method, the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment to obtain a pre-formed nickel-titanium thin-walled tube.

[0137] Step S607: The pre-formed nickel-titanium thin-walled tube is subjected to stress-relieving heat treatment and electrochemical polishing to obtain the formed nickel-titanium thin-walled tube.

[0138] Optionally, during the forming process, the control equipment can control the nickel-titanium thin-walled tube to advance axially. The nickel-titanium thin-walled tube can have multiple forming zones along its axial direction. For each forming zone, the control equipment can apply a pulsed current to the forming zone and the mold using a pulsed current-assisted forming method, and apply ultrasonic vibration at the contact interface between the forming zone and the mold and / or mandrel using an ultrasonic vibration-assisted forming method. The control equipment can also collect forming parameters such as the temperature rise, resistivity change rate, and deformation deviation of the nickel-titanium thin-walled tube in real time. Based on the real-time collected temperature rise, the control equipment can adjust the peak value and / or pulse duration of the pulsed current. The deformation deviation of the collection is adjusted by regulating the ultrasonic amplitude and / or the feed speed. At least one of the pulse current peak value, pulse duration, ultrasonic amplitude and feed speed is adjusted according to the real-time collected resistance change rate, so that the forming parameters corresponding to the adjusted auxiliary forming method are within the preset forming parameter range. The control equipment can perform auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted pulse current assisted forming method and / or the adjusted ultrasonic vibration assisted forming method to obtain a preliminary formed nickel-titanium thin-walled tube. The preliminary formed nickel-titanium thin-walled tube is then subjected to stress relief heat treatment and electrochemical polishing treatment to obtain the final formed nickel-titanium thin-walled tube.

[0139] The aforementioned method for forming nickel-titanium thin-walled tubes can establish a real-time closed-loop adjustment mechanism based on forming parameters such as temperature rise, resistance change rate, and roundness deviation. This mechanism synchronously adjusts the pulse current and ultrasonic vibration used to form medical nickel-titanium micro-thin-walled tubes, ensuring that the forming parameters generated during the forming process remain within a preset range. This constructs a collaborative precision forming system targeting the thermal, mechanical, and phase transformation coupling characteristics of medical nickel-titanium materials, enabling the forming results of medical nickel-titanium micro-thin-walled tubes to balance geometric accuracy, surface integrity, and functional consistency.

[0140] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0141] Based on the same inventive concept, this application also provides a nickel-titanium thin-walled tube forming apparatus for implementing the above-described nickel-titanium thin-walled tube forming method. The solution provided by this apparatus is similar to the solution described in the above method; therefore, the specific limitations of one or more nickel-titanium thin-walled tube forming apparatus embodiments provided below can be found in the limitations of the nickel-titanium thin-walled tube forming method described above, and will not be repeated here.

[0142] In one exemplary embodiment, a forming apparatus for a nickel-titanium thin-walled tube is provided, comprising: a loading module, an adjusting module, and a forming module, wherein:

[0143] The loading module is used to perform auxiliary forming processing on the nickel-titanium thin-walled tube according to the auxiliary forming method during the forming process of the nickel-titanium thin-walled tube to be formed, and to determine the forming parameters of the nickel-titanium thin-walled tube; the auxiliary forming method includes at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method.

[0144] An adjustment module is used to adjust the auxiliary forming method according to the forming parameters, so that the forming parameters corresponding to the adjusted auxiliary forming method are within a preset forming parameter range;

[0145] The forming module is used to perform auxiliary forming processing on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method, so as to obtain the formed nickel-titanium thin-walled tube.

[0146] In an exemplary embodiment, the loading module is further configured to control the nickel-titanium thin-walled tube to advance axially; to perform auxiliary forming processing on each forming region of the nickel-titanium thin-walled tube according to the auxiliary forming method; the deformation amount of each forming region does not exceed a preset threshold, and the auxiliary forming processing includes at least one of diameter reduction forming processing and rounding forming processing.

[0147] In an exemplary embodiment, the loading module is further configured to apply a pulsed current to the forming area and the mold according to the pulsed current assisted forming method; and to apply ultrasonic vibration at the contact interface between the forming area and the mold, and / or at the contact interface between the forming area and the mandrel according to the ultrasonic vibration assisted forming method; the mold is placed outside the nickel-titanium thin-walled tube, and the mandrel is placed inside the cavity of the nickel-titanium thin-walled tube.

[0148] In an exemplary embodiment, the loading module is further configured to trigger the loading of the pulse current when the forming region enters the effective loading region, and to stop loading the pulse current when the forming region leaves the effective loading region.

[0149] In an exemplary embodiment, the loading module is further configured to load the ultrasonic vibration according to a preset timing sequence, so that the ultrasonic vibration is coupled with the pulsed current.

[0150] In an exemplary embodiment, the above-described adjustment module is further configured to adjust the peak pulse current and / or pulse duration according to the temperature rise value; adjust the ultrasonic amplitude and / or feed speed according to the deformation deviation; and adjust at least one of the peak pulse current, pulse duration, ultrasonic amplitude, and feed speed according to the resistance change rate.

[0151] In an exemplary embodiment, the forming module is further configured to perform auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method to obtain a pre-formed nickel-titanium thin-walled tube; and to perform stress-relieving heat treatment and electrochemical polishing treatment on the pre-formed nickel-titanium thin-walled tube to obtain the formed nickel-titanium thin-walled tube.

[0152] Each module in the aforementioned nickel-titanium thin-walled tube forming apparatus can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0153] In an exemplary embodiment, a computer device is provided, which may be a terminal. The computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are connected to the system bus via the input / output interface. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface of the computer device is used for exchanging information between the processor and external devices. The communication interface of the computer device is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a method for forming a nickel-titanium thin-walled tube. The display unit of the computer device is used to form a visually visible image and may be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0154] Those skilled in the art will understand that the above structure is only a part of the structure related to the present application and does not constitute a limitation on the computer device on which the present application is applied. The specific computer device may include more or fewer components than shown in the above structure, or combine certain components, or have different component arrangements.

[0155] In one exemplary embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0156] In one exemplary embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above-described method embodiments.

[0157] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0158] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0159] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0160] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0161] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for forming a nickel-titanium thin-walled tube, characterized in that, The method includes: During the forming process of the nickel-titanium thin-walled tube to be formed, the nickel-titanium thin-walled tube is subjected to auxiliary forming process according to the auxiliary forming method, and the forming parameters of the nickel-titanium thin-walled tube are determined; the auxiliary forming method includes at least one of pulse current assisted forming method and ultrasonic vibration assisted forming method. The auxiliary forming method is adjusted according to the forming parameters so that the forming parameters corresponding to the adjusted auxiliary forming method are within the preset forming parameter range. According to the adjusted auxiliary forming method, the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment to obtain the formed nickel-titanium thin-walled tube.

2. The method according to claim 1, characterized in that, The nickel-titanium thin-walled tube has multiple forming zones arranged along the axial direction; The auxiliary forming process for the nickel-titanium thin-walled tube, according to the auxiliary forming method, includes: Control the nickel-titanium thin-walled tube to advance axially; According to the auxiliary forming method, each forming region of the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment; the deformation of each forming region does not exceed a preset threshold, and the auxiliary forming treatment includes at least one of diameter reduction forming treatment and rounding forming treatment.

3. The method according to claim 2, characterized in that, The auxiliary forming process for each forming region of the nickel-titanium thin-walled tube according to the aforementioned auxiliary forming method includes: According to the pulsed current assisted forming method, a pulsed current is applied to the forming area and the mold; According to the ultrasonic vibration-assisted forming method, ultrasonic vibration is applied at the contact interface between the forming area and the mold, and / or at the contact interface between the forming area and the mandrel; the mold is placed outside the nickel-titanium thin-walled tube, and the mandrel is placed inside the cavity of the nickel-titanium thin-walled tube.

4. The method according to claim 3, characterized in that, The forming area corresponds to the effective loading area of ​​the mold; Applying pulsed current to the forming area and the mold includes: When the forming area enters the effective loading area, the pulse current is triggered. When the forming area leaves the effective loading area, the pulse current is stopped.

5. The method according to claim 3, characterized in that, Applying ultrasonic vibration at the contact interface between the forming area and the mold, and / or at the contact interface between the forming area and the mandrel, includes: The ultrasonic vibration is applied according to a preset timing sequence so that the ultrasonic vibration is coupled with the pulsed current.

6. The method according to claim 1, characterized in that, The forming parameters include at least the temperature rise, resistivity change rate, and deformation deviation of the nickel-titanium thin-walled tube, and the deformation deviation includes at least one of roundness deviation and wall thickness deviation. The step of adjusting the auxiliary forming method according to the forming parameters includes at least one of the following: Adjust the peak pulse current and / or pulse duration based on the temperature rise value; Adjust the ultrasonic amplitude and / or feed rate according to the deformation deviation; Based on the resistance change rate, at least one of the pulse current peak value, pulse duration, ultrasonic amplitude, and feed rate is adjusted.

7. The method according to claim 1, characterized in that, The step of performing auxiliary forming treatment on the nickel-titanium thin-walled tube according to the adjusted auxiliary forming method to obtain the formed nickel-titanium thin-walled tube includes: According to the adjusted auxiliary forming method, the nickel-titanium thin-walled tube is subjected to auxiliary forming treatment to obtain a pre-formed nickel-titanium thin-walled tube. The pre-formed nickel-titanium thin-walled tube is subjected to stress-relief heat treatment and electrochemical polishing to obtain the formed nickel-titanium thin-walled tube.

8. A forming system for nickel-titanium thin-walled tubes, characterized in that, The system includes a controller, a mold, and a mandrel; the mold is placed outside the nickel-titanium thin-walled tube to be formed, and is used to define the outer contour of the nickel-titanium thin-walled tube; the mandrel is placed inside the cavity of the nickel-titanium thin-walled tube, and is used to support the nickel-titanium thin-walled tube; the controller is used to perform the steps of the method according to any one of claims 1 to 7.

9. The system according to claim 8, characterized in that, The mandrel includes a supportable stiffness section and a retractable transition section. The supportable stiffness section corresponds to the forming area of ​​the nickel-titanium thin-walled tube and the effective loading area of ​​the mold. The retractable transition section is located on both sides of the supportable stiffness section.

10. The system according to claim 8, characterized in that, The formed nickel-titanium thin-walled tubes are used to manufacture vascular stents, thrombectomy stents, filters, valve support structures, or delivery system reinforcement tubes.

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