WO2017177477A1 - 一种镍钛合金梯度柔性根管锉及其制造方法 - Google Patents

一种镍钛合金梯度柔性根管锉及其制造方法 Download PDF

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Publication number
WO2017177477A1
WO2017177477A1 PCT/CN2016/079980 CN2016079980W WO2017177477A1 WO 2017177477 A1 WO2017177477 A1 WO 2017177477A1 CN 2016079980 W CN2016079980 W CN 2016079980W WO 2017177477 A1 WO2017177477 A1 WO 2017177477A1
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Prior art keywords
root canal
gradient
flexible
martensite
temperature
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PCT/CN2016/079980
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English (en)
French (fr)
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王中
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深圳市速航科技发展有限公司
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Priority to US15/603,695 priority Critical patent/US10149737B2/en
Publication of WO2017177477A1 publication Critical patent/WO2017177477A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C22C30/02—Alloys containing less than 50% by weight of each constituent containing copper
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor

Definitions

  • the invention relates to a root canal, in particular to a nickel-titanium alloy gradient flexible root canal and a manufacturing method thereof.
  • Root canal treatment is currently an ideal and mature treatment for various diseases such as pulpitis, pulp necrosis, gangrene, and tooth fracture.
  • the root canal is the main device used to thoroughly clean the inside of the root canal and the root canal wall, to remove the diseased tissue, and to create a complete and smooth root canal lumen.
  • the structure of the root canal is composed of the working part 1, the handle 2 and the positioning ring 3.
  • the working part has a certain sectional shape, the outer contour has a certain taper, and the thread has a thread distribution thereon, and the thread has a certain spiral angle ⁇ , such as Figure 1 shows.
  • the root canal device When the root canal device is working, it rotates in the root canal 4 at a certain rotational speed, and cuts the inner surface of the root canal to achieve the purpose of cleaning and shaping the root canal, as shown in FIG. 2 .
  • the root canal has a curved inverted cone-like structure, which is often more pronounced at the tip of the root canal.
  • the root canal is subject to severe alternating bending deformation during operation.
  • the root canal In order to completely clean the inside of the root canal, the root canal should meet at least three requirements: First, the root canal has a certain cutting ability, in order to effectively remove the diseased tissue and complete the shaping of the root canal; The front end should have a certain flexibility, can guide the root canal to reach the bottom of the root canal smoothly, clean and shape the tip of the root canal, and prevent the stepping or lateral wear on the inner wall of the root canal; third, the root canal should be high The anti-bending fatigue fracture life prevents the fracture of the root canal during use, resulting in a medical accident.
  • the traditional stainless steel root canal has good cutting performance due to its high strength, but due to its high rigidity, it is easy to cause the inner surface of the root canal to be stepped and side worn.
  • Nickel-titanium alloy has excellent elasticity and good biocompatibility, and is widely used in various medical devices, including root canal.
  • Nickel-titanium root canal is favored by the market because of its better flexibility and fracture resistance than stainless steel root canal.
  • Nickel-titanium alloy undergoes a phase transition between austenite and martensite under certain conditions, as shown in Fig. 3. As the alloy increases with temperature, it begins to transform from martensite to austenite, and at the end of the Af temperature transition, the material is 100% austenite. As the temperature decreases, The transition from austenite to martensite begins at the temperature of Ms, and at the end of the Mf temperature transition, the material is 100% martensite phase. This martensite transformed from austenite due to a decrease in temperature is called hot martensite. Austenite has a cubic structure, while martensite has a monoclinic structure, and martensite has a twin structure.
  • the martensitic transformation is reversible.
  • the so-called reversibility means that if cooled, the austenite transforms into martensite. If heated, the martensite transforms into austenite. Since the austenite and martensite have the same chemical composition, the crystal structure is different. However, the temperature range is different. Therefore, if repeated heating-cooling, the tissue transformation is repeated between austenite and martensite.
  • the structure of the material determines its performance, and different tissues have different properties. The performance also changes accordingly.
  • the austenite phase transition to martensite phase begins and ends at Ms, Mf; the martensite begins to reverse phase with the parent phase, and the final temperature is called As, Af.
  • the twin structure of the hot martensite is self-cooperating.
  • the thermal martensite in the self-cooperating twin state is deformed, the twin crystals are reoriented to form a single-oriented twin structure, and the material exhibits excellent deformability and excellent toughness, as shown in Fig. 4 (a). ) shown.
  • the austenite undergoes stress-induced martensitic transformation under the action of stress, and the austenite transforms into martensite, while the alloy exhibits large deformation.
  • This martensite produced by stress is called stress-induced martensite.
  • the stress-induced martensite is unstable.
  • the stress-induced martensite spontaneously transforms into an austenite phase, and the nickel-titanium alloy returns to its original shape. At this time, the nickel-titanium alloy exhibits a superelastic behavior as shown in (b) of FIG.
  • the yield strength of Nitinol varies with temperature, as shown in Figure 5, due to changes in the internal organization of the alloy at different temperature intervals.
  • the microstructure of the alloy In the temperature range of zone I, the microstructure of the alloy is a total thermal martensite structure; in the temperature range of zone II, the microstructure of the alloy is a full austenite structure; in the temperature range of zone III between zone I and zone II, As the temperature increases, the content of hot martensite in the alloy decreases and the austenite content increases. Due to changes in the alloy structure, the strength of the alloy will also vary with temperature.
  • the yield stress level of Nitinol In the AB segment, the yield stress level of Nitinol is relatively low, and the deformation mechanism at this time is mainly the reorientation of martensite twins.
  • the yield stress-temperature curve of NiTi alloy exhibits a positive gradient relationship.
  • the deformation at this stage is completed by the twin reorientation of hot martensite and the transformation of austenite to stress induced martensite.
  • the deformation of the CD segment mainly by austenite Yield deformation to complete.
  • the alloy In the high stress region of interval II, both the fully austenitic region, the alloy exhibits a completely superelastic behavior. In the III temperature range, the alloy exhibits shape memory or partial superelastic behavior.
  • the currently disclosed nickel-titanium root canal is one of the superelastic properties of nickel-titanium alloy, which is called superelastic nickel-titanium root canal.
  • the Af temperature of the superelastic nickel-titanium root canal material is designed to be below the root canal working temperature of 37 ° C (human body temperature).
  • 37 ° C human body temperature
  • the inside of the root canal is a full austenite structure.
  • stress induced martensite occurs inside. After the stress is removed, the stress-induced martensite is transformed into austenite and exhibits superelastic behavior, as shown in (b) of FIG.
  • the root canal has a high strength and thus has good cutting performance.
  • Nitinol root canal is called a heat activated root canal.
  • the Af temperature of the Nitinol material from which such root canals are made is designed to be higher than 37 °C.
  • the structure inside the root canal is hot martensite, or a mixture of hot martensite and austenite.
  • the martensite inside will undergo reorientation of the self-cooperating twin substructure, forming a single-oriented twin structure, while the root canal exhibits large deformation, as shown in Fig. 4. (a) is shown.
  • the present invention provides a nickel-titanium alloy gradient flexible root canal and a method of manufacturing the same.
  • the present invention provides a nickel-titanium alloy gradient flexible root canal comprising a working portion, a handle and a positioning ring, the working portion being coupled to the handle, the working portion including a tip end section, a transition section and near the a root section of the handle, the positioning ring being disposed on a root section of the working portion.
  • the tip end portion has a length L 1
  • the transition portion has a length L 2
  • the root portion has a length L 3 , wherein the tip end portion of the martensite to the austenite
  • the phase transition end temperature of the bulk transformation is higher than or equal to 37 ° C
  • the phase transition end temperature of the martensite to austenite transformation of the root section is lower than 37 ° C.
  • the tip section is martensite, or a mixture of martensite and austenite, the root section being full austenite.
  • L 1 is 1-9 mm and L 2 is 2-5 mm.
  • the phase transition end temperature of the martensite to austenite transformation of the tip section is 37-65 ° C, and the phase transition of the martensite to austenite transformation of the root section is terminated.
  • Af is 0-30 °C.
  • the invention also provides a method for manufacturing a nickel-titanium alloy gradient flexible root canal, comprising the following steps:
  • the nickel-titanium alloy material is subjected to cold drawing and straightening annealing treatment, the raw material for manufacturing the gradient flexible root canal is obtained;
  • the root canal blank is subjected to a flexible gradient treatment in a flexible gradient processing device to prepare a root canal blank having gradient flexibility;
  • the root canal blank with gradient flexibility is mechanically processed to prepare a root canal needle with gradient flexibility
  • the root canal needle with gradient flexibility is installed through the handle and the positioning ring to form a Nitinol gradient flexible root canal.
  • the nickel-titanium alloy material is subjected to cold drawing and straightening annealing treatment, the cold drawing deformation is 35-45%, the annealing temperature is 450-600 ° C, and the annealing time is 30-120 minutes.
  • the phase transition temperature of the martensite to austenite transformation of the post-Ni-Ti alloy material is 0-30 ° C.
  • the flexible gradient processing device includes a heat conductor, an electric heating body and a heat retaining body, and the heat conductor has a hole formed therein, and the tip end of the root pipe is inserted into the hole, and the heat conductor is The lower part is closely attached to the electric heating body, and the heat insulating body surrounds the heating body and the lower half of the heat conductor, and in the upper half of the heat conductor, there is no surrounding body, and a bottom-up gradient can be formed in the heat conductor.
  • Temperature Field is a heat conductor, an electric heating body and a heat retaining body, and the heat conductor has a hole formed therein, and the tip end of the root pipe is inserted into the hole, and the heat conductor is The lower part is closely attached to the electric heating body, and the heat insulating body surrounds the heating body and the lower half of the heat conductor, and in the upper half of the heat conductor, there is no surrounding body, and a bottom-up gradient can be formed in the heat conductor.
  • the flexible gradient processing device realizes the tip phase of the root canal blank by controlling the heating temperature of the heating body, the height of the heat conductor, the depth of the root canal blank insertion hole, and the heating time.
  • the precise control of the temperature change, the phase transition of the martensite to the austenite transformation at the tip of the root canal material is at a temperature of 37-65 ° C.
  • the invention also provides a method for manufacturing a nickel-titanium alloy gradient flexible root canal, which is subjected to cold drawing and straightening annealing treatment, and then mechanically processed into a root canal needle, and the formed root canal
  • the needle is inserted into the flexible gradient processing device for processing to prepare a gradient-flexible root canal needle; and then the positioning ring of the handle is installed to form a Nitinol gradient flexible root canal.
  • the invention has the beneficial effects of having good cutting performance, good compliant performance and high fatigue fracture resistance, thereby fundamentally improving the existing defects of the existing Nitinol root canal to greatly improve the use of the root canal. Sex, safety and longevity.
  • Figure 1 Structure diagram of the root canal.
  • Figure 3 Schematic diagram of thermal martensitic transformation in a nickel-titanium alloy.
  • FIG. Schematic diagram of the internal structure of martensite (a), austenite (b) and its deformation.
  • Figure 5 Schematic diagram of the relationship between yield stress and deformation temperature of NiTi alloy.
  • Figure 6 Schematic diagram of the relationship between the phase transition temperature of cold deformed NiTi alloy and the annealing temperature.
  • Figure 7 Schematic diagram of the relationship between phase transition temperature and aging temperature of nickel-titanium alloy.
  • Figure 8 Schematic diagram of a Nitinol gradient flexible root canal.
  • Figure 9 Schematic diagram of a root canal blank and a flexible gradient treatment device.
  • Figure 10 is a schematic view of a root canal blank and a root canal.
  • Figure 11 Schematic diagram of the root canal needle and flexible gradient treatment device.
  • the invention provides a nickel-titanium alloy gradient flexible root canal and a manufacturing method thereof, which fundamentally improve the existing defects of the existing nickel-titanium root canal to greatly improve the usability, safety and life of the root canal.
  • the phase transition temperature of Nitinol can be controlled and adjusted by various means. Cold deformation has a certain influence on the phase transition temperature of Nitinol. After cold deformation of the alloy, a large number of crystal defects such as dislocations are generated in the structure, which leads to an increase in the strength of the alloy. The phase transformation resistance between the martensite and the austenite in the alloy increases, making the phase transformation of the alloy difficult, and the phase transformation The temperature is lowered. After the cold-deformed alloy is annealed, the cold-deformed structure will recover, and the density of crystal defects such as dislocations will decrease, resulting in a decrease in the strength of the alloy and an increase in the phase transition temperature of the alloy.
  • Fig. 6 is a graph showing the change of the phase transition temperature of the Ti-50.6at%Ni alloy with annealing temperature after annealing at different temperatures for 1 hour after 30% cold deformation.
  • the matrix composition of Nitinol has a significant effect on the phase transition temperature of the alloy.
  • the practical nickel-titanium alloy composition is generally in the range of Ti-49.8 at% Ni to Ti-51.2 at% Ni (atomic ratio).
  • the phase transition temperature (such as As, Af, Ms, Mf, etc.) of the nickel-titanium alloy is determined by the content of Ni element in the alloy matrix. The higher the Ni content in the alloy matrix, the lower the phase transition temperature of the alloy. Studies have shown that for every 0.1 at% (atomic ratio) increase in the Ni content in the nickel-titanium alloy, the alloy has a Ms temperature drop of 12 °C.
  • the high-Ni nickel-titanium alloy has a second phase precipitated during the aging heat treatment, and the precipitated phase is a Ti 3 Ni 4 phase. While the Ti 3 Ni 4 phase is precipitated, the Ni content of the alloy matrix is lowered, and the phase transition temperature of the alloy is increased.
  • Fig. 7 is a graph showing the change of the phase transition temperature of the alloy after the aging of the Ti-50.6at%Ni alloy after complete solution treatment for 1 hour at different temperatures.
  • the ideal Nitinol root canal must meet at least three properties, good cutting performance, good flexibility and high fatigue fracture resistance, and the above three properties are contradictory.
  • Good cutting performance means that the root canal needs to have higher strength, and good softness performance requires that the strength of the root canal is not too high, and the high bending fatigue fatigue life requires the internal structure of the root canal to be Markov. Body or a mixture of martensite and austenite. This is not possible with a root canal of a nickel-titanium alloy having a single phase transition temperature.
  • the Af temperature of the alloy is lower than 37 ° C, and the material of each point of the root canal has the same phase transition temperature, and the Af temperature of each point is lower than 37 ° C.
  • the disclosed nickel-titanium alloy thermally activated root canal has an Af temperature of more than 37 ° C, and the material of each point of the root canal has the same phase transition temperature, and the Af temperature of each point is higher than 37 ° C.
  • the root canal has good flexibility and good bending fatigue fatigue life, the cutting ability is low due to the low strength of the alloy, especially the removal of the large amount of the middle and upper parts of the root canal. It is extremely difficult, resulting in poor performance of the root canal.
  • the present invention proposes a nickel-titanium alloy gradient flexible root canal and a method for producing the same.
  • the present invention relates to a Nitinol gradient flexible root canal comprising a working portion 1, a handle 2 and a positioning ring 3, the working portion 1 being coupled to the handle 2, the working portion 1 comprising a tip end section 11, a transition section 12 and a root section 13 adjacent the handle 2, said positioning ring 3 being disposed on the root section 13 of the working portion 1, starting from the tip end of the tip end section 11, along
  • the length direction of the Nitinol gradient flexible root canal to the root section 13 gradually decreases the phase transition temperature Af of the martensite to austenite transformation at each point on the Nitinol gradient flexible root canal.
  • the phase transition of martensite to austenite is terminated by the temperature Af, which can also be referred to as Af temperature.
  • the length of the tip section 11 is L 1
  • the length of the transition section 12 is L 2
  • the length of the root section 13 is L 3 martensitic wherein said tip segment 11
  • the phase transition end temperature to Austenite is higher than or equal to 37 ° C
  • the phase transition end temperature of the martensite to austenite transformation of the root section 13 is lower than 37 ° C.
  • the tip end section 11 is a mixture of martensite or martensite and austenite, and the root section 13 is full austenite.
  • L 1 is preferably 1-9 mm, and L 1 may preferably be any one of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, and 9 mm.
  • L 2 is preferably 2-5 mm, and L 2 may preferably be any of 2 mm, 3 mm, 4 mm, and 5 mm.
  • the phase transition end temperature Af of the martensite to the austenite transformation of the tip end portion 11 is preferably 37-65 ° C, and the martensite to austenite transformation phase of the tip end portion 11
  • the end temperature Af may preferably be any one of 37 ° C, 40 ° C, 45 ° C, 50 ° C, 55 ° C, 60 ° C, and 65 ° C, and the transformation of the martensite to the austenite transformation of the root portion 13 is finished.
  • the temperature Af is preferably 0-30 ° C, and the phase transition end temperature of the martensite to austenite transformation of the root section 13 may preferably be 0 ° C, 5 ° C, 10 ° C, 15 ° C, 20 ° C, 25 ° C, Any one of 30 °C.
  • the structure in the tip section 11 is martensite or a mixture of martensite and austenite, and the structure of the root section 13 is a full austenite structure. Since the internal structure of the Nitinol gradient flexible root canal is gradual, the strength along the axial direction of the root canal is also gradually changed, as shown in FIG.
  • the internal structure is martensite or a mixture of martensite and austenite
  • the strength of the segment is low, and it has excellent flexibility and can be smoothly Arrive at the tip of the root canal and clean the tip of the canal.
  • the deformation mechanism of the tip end section 11 is mainly a reorientation process of self-cooperating martensite twinning, no crystal defects are generated during repeated deformation, and thus the tip end section 11 has an extremely high bending fatigue life, which is greatly reduced.
  • the risk of fracture of the root canal tip is shown in Figures 4 and 5.
  • the microstructure in the alloy is austenitic, and the deformation mechanism is carried out in a stress-induced martensitic transformation.
  • the strength of the alloy is high and therefore good.
  • the cutting performance, but the compliance of the root section 13 is worse than that of the L1 section, as shown in Figs. 4 and 5.
  • Nitinol gradient flexible root canal Since the internal structure of the Nitinol gradient flexible root canal is gradual in the axial direction, its flexibility and strength exhibit a gradient change along the axial direction of the root canal.
  • the invention also provides a method for manufacturing a nickel-titanium alloy gradient flexible root canal.
  • the manufacture of nitinol gradient flexible root canal is achieved in that the composition of the alloy used is generally selected in the range of Ti-50.2 at% Ni to Ti-5 1.2 at% Ni (atomic ratio).
  • the alloy needs to be cold drawn to prepare a wire of a certain diameter, and the deformation of the cold drawing should be in the range of 35-45%.
  • the cold drawn alloy wire is then annealed at 450-600 ° C for 30-120 minutes to prepare the material for the gradient flexible root canal.
  • the Af temperature of the Nitinol wire is controlled in the range of 0-30 ° C, as described in Figures 6 and 7, for cold-deformed and high-nickel Nitinol, by controlling the annealing or aging temperature and time, The phase transition temperature of Nitinol is controlled and adjusted.
  • a nickel-titanium alloy gradient flexible root canal is manufactured by first using the above-mentioned raw material machine
  • the root canal blank 5 is machined into a certain length, and the root canal blank 5 is subjected to a flexible gradient treatment, as shown in FIG.
  • the flexible gradient processing apparatus is composed of a heat conductor 6, an electric heating body 7, and a heat insulator 8, and a hole 9 is formed in the heat conductor, and a tip portion of the root tube blank 5 is inserted into the hole 9.
  • An electric heating body 7 is closely attached to the lower portion of the heat conductor 6, and the heat insulating body 8 surrounds the heating body 7 and the lower half of the heat conductor 6 to prevent heat from being dissipated from below; and in the upper half of the heat conductor 6, there is no heat preservation.
  • heat can be dissipated from the upper half of the heat conductor 6, so that a bottom-up gradient temperature field can be formed in the heat conductor 6. Due to the heat conduction effect, the root canal material 5 inserted in the hole 9 is heated, and the temperature at which the root canal material 5 is heated is also distributed in a gradient from the bottom to the top in the axial direction. Since the root canal billet 5 is axially bottomed upward from the tip end, the heating temperature is gradually increased, thereby causing the root canal material blank 5 to gradually change upward from the tip end in the tissue.
  • the re-recovery of the cold-deformed structure and the precipitation of the Ti 3 Ni 4 phase occur in the tip end section 11 of the root canal billet 5, as described in FIGS. 6 and 7.
  • the cold deformed structure will recover when heated, resulting in a decrease in crystal defects in the structure and an increase in the phase transition temperature of the alloy.
  • the Ni Ni-titanium alloy has a phase Ti 3 Ni 4 precipitated during the aging heat treatment, so that the Ni content of the alloy matrix is lowered.
  • the phase transition temperature of the alloy will increase accordingly. Under the above dual action, the temperature of the Af of the tip of the root canal billet 5 rises.
  • the change in the structure of the tip end portion 11 and the transition portion 12 of the root canal material 5 is also gradually changed with the temperature gradient, thereby realizing the root canal.
  • the flexibility and strength of the tantalum blank 5 exhibit a gradient change characteristic in the axial direction. Since the root section 13 is not heated during the flexible gradient treatment, the Af temperature of the section does not change, and the Af temperature of the raw material is maintained, which is 0-30 °C.
  • the heating temperature of the heating body 7, the height of the heat conductor 6, the depth of the root canal blank 5 insertion hole 9, and the heating time By controlling the heating temperature of the heating body 7, the height of the heat conductor 6, the depth of the root canal blank 5 insertion hole 9, and the heating time, precise control of the phase transition temperature of the tip tube blank 5 can be achieved.
  • the Af temperature at the tip of the root canal blank 5 should be controlled in the range of 37-65 °C.
  • the root tube ⁇ blank 5 after the flexible gradient treatment is mechanically formed to obtain the desired root canal needle 10, as shown in FIG.
  • the root canal needle 10 is then mounted through the handle 2 and the positioning ring 3 to form a Nitinol gradient flexible root canal as described herein.
  • the invention relates to a Nitinol gradient flexible root canal, the Af temperature of the tip section 11 is 37-65 ° C, and the Af temperature of the root section 13 is 0-30 ° C.
  • the invention also provides a method for manufacturing a nickel-titanium alloy gradient flexible root canal, which is prepared by cold-drawing an alloy having a composition range of Ti-50.2at%Ni to Ti-51.2at%Ni (atomic ratio). For a certain diameter of wire, the amount of deformation of cold drawing should be in the range of 35-45%.
  • the cold drawn alloy wire is further annealed at 450-600 ° C for 30-120 minutes, and then mechanically formed into a root canal needle 10 .
  • the processed root canal needle 10 is inserted into the flexible gradient processing apparatus shown in Fig. 9 to perform a flexible gradient treatment, as shown in Fig. 11.
  • the flexible grit-treated root canal needle 10 is then mounted through the handle 2 and the positioning ring 3 to form the Nitinol gradient flexible root canal of the present invention.

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Abstract

一种镍钛合金梯度柔性根管锉及其制造方法，根管锉包括工作部（1）、柄部（2）和定位环（3），所述工作部（1）与所述柄部（2）连接，所述工作部（1）包括尖端段（11）、过渡段（12）和靠近所述柄部（2）的根部段（13），所述定位环（3）设置在所述工作部（1）的根部段（13）上，从所述尖端段（11）的尖端开始，沿所述镍钛合金梯度柔性根管锉的长度方向至根部段（13），所述镍钛合金梯度柔性根管锉上各点的马氏体向奥氏体转变的相变终了温度Af逐步降低。

Description

一种镍钛合金梯度柔性根管锉及其制造方法 技术领域
本发明涉及根管锉，尤其涉及一种镍钛合金梯度柔性根管锉及其制造方法。
背景技术
根管治疗是目前治疗各种牙髓炎、牙髓坏死、坏疽、牙齿折断等疾病比较理想和成熟的治疗方法。根管锉是用来对病变根管内部和根管壁进行彻底清理，去处病变组织，塑造出完整、光滑根管内腔的主要器械。
根管锉的结构由工作部1、柄部2和定位环3组成，工作部具有一定的截面形状，外轮廓有一定的锥度，且有螺纹分布其上，螺纹具有一定的螺旋角φ，如图1所示。
根管锉器械在工作时，是以一定的转速在根管4内做旋转运动，切削根管内表面，以达到根管清洁与塑形的目的，如图2所示。根管呈弯曲倒锥状结构，往往在根管尖部弯曲更为显着，根管锉在工作时会受到严重的交变弯曲变形。
为了全面清理根管内部，根管锉应至少满足三个方面的要求：一是根管锉具有一定的切削能力，以便高效的去除病变组织和完成根管的塑形；二是根管锉的前端应有一定的柔顺性，能引导根管锉顺利到达根管底部，对根管尖部进行清理与塑形，同时防止在根管内壁产生台阶或侧穿；三是根管锉应有高的抗弯曲疲劳断裂寿命，防止在使用时根管锉的断裂，造成医疗事故。
传统的不锈钢根管锉由于强度高，具有较好的切削性能，但由于刚度较大，很容易造成根管内表面台阶和侧穿。镍钛合金具有优异的弹性和良好的生物兼容性，被广泛应用于各类医疗器械，也包括根管锉。镍钛合金根管锉由于具有比不锈钢根管锉更好的柔顺性和抗断裂性能而受到市场的青睐。
镍钛合金在一定条件下会发生奥氏体与马氏体之间的相变，如图3。当合金随着温度的升高，在As温度开始由马氏体向奥氏体转变，在Af温度转变结束，材料中为百分之百的奥氏体相。随着温度降低， 在Ms温度开始发生由奥氏体向马氏体的转变，在Mf温度转变结束，材料中为百分之百的马氏体相。这种由于温度降低由奥氏体转变而来的马氏体被称作热马氏体。奥氏体具有立方结构，而马氏体具有单斜结构，马氏体的亚结构为孪晶。
马氏体相变是可逆的。所谓可逆性是指如果冷却，奥氏体会转变为马氏体，如果加热，则马氏体又会转变为奥氏体，由于奥氏体与马氏体化学成分相同，只是晶体结构不同，而存在的温度范围不同，因此，如果反复加热—冷却，则组织转变在奥氏体—马氏体之间也反复进行，材料的组织决定了其性能，不同的组织具有不同的性能，组织变了则性能也相应的发生变化。
奥氏体相向马氏体相转变开始、终了温度称为Ms、Mf；马氏体向母相逆转变开始、终了温度称为As、Af。
热马氏体的孪晶亚结构呈自协作状态。当处于自协作孪晶状态的热马氏体变形时，孪晶会发生再取向，形成单一取向的孪晶结构，材料表现出优异的变形能力和极好的韧性，如图4中的(a)所示。当镍钛合金在奥氏体状态下变形时，奥氏体在应力的作用下会发生应力诱发马氏体相变，奥氏体转变为马氏体，同时合金表现出大的变形。这种由应力作用产生的马氏体被称作应力诱发马氏体。应力诱发马氏体是不稳定的，在应力去除后，应力诱发的马氏体会自发转变成为奥氏体相，镍钛合金恢复原来的形状。此时镍钛合金呈现出超弹性行为，如图4中的(b)所示。
镍钛合金的屈服强度随着温度变化而变化，如图5所示，这是由于在不同温度区间，合金内部组织的变化造成的。在Ⅰ区温度范围内，合金的组织为全热马氏体组织；在Ⅱ区温度范围内，合金的组织为全奥氏体组织；在Ⅰ区和Ⅱ区之间的Ⅲ区温度范围内，随着温度的升高，合金中的热马氏体组织含量在不断减少，奥氏体组织含量在不断增加。由于合金组织的变化，合金的强度也会随温度的变化而不同。在AB段，镍钛合金的屈服应力水平比较低下，此时的变形机制主要是马氏体的孪晶再取向。在BC段，镍钛合金的屈服应力-温度曲线呈现正的梯度关系，此阶段的变形是由热马氏体的孪晶再取向和奥氏体向应力诱发马氏体的转变共同来完成。在CD段的变形，主要是由奥氏体的 屈服变形来完成。在区间Ⅱ的高应力区，既全奥氏体区，合金呈现完全超弹性行为。而在Ⅲ温度区间，合金呈现形状记忆或部分超弹性行为。
目前公开的镍钛合金根管锉，一类是利用镍钛合金的超弹性性能，被称为超弹性镍钛合金根管锉。制造超弹性镍钛合金根管锉材料的Af温度，被设计在根管锉工作温度37℃(人体环境温度)以下。在37℃工作温度环境下，根管锉内部为全奥氏体组织。根管锉在使用过程中受力弯曲变形时，其内部发生应力诱发马氏体。在去除应力后，应力诱发马氏体又转变为奥氏体，呈现出超弹性行为，如图4中的(b)所示。该种根管锉具有较高的强度，因而具有较好的切削性能。但超弹性镍钛合金根管锉在使用过程中，其内部会不断发生周期性的应力诱发马氏体与奥氏体之间的相转变。这种相变虽然可以产生较大的弹性应变，但在奥氏体与马氏体转变的过程中，会产生一定的晶体缺陷—位错。随着奥氏体与马氏体相变不断的重复进行，材料内部的晶体缺陷也会不断的积累，最终导致根管锉的断裂，使得镍钛合金超弹性根管锉的抗弯曲疲劳寿命低下，大大影响了根管锉的使用安全性。一般断裂的位置在距根管锉尖端3-6毫米的范围内，这是由于根管的尖部弯曲比较严重的原因。
另外一类镍钛合金根管锉被称作热激活根管锉。制造该类根管锉的镍钛合金材料的Af温度被设计在高于37℃。在37℃工作温度环境下，该类根管锉内部的组织为热马氏体、或热马氏体和奥氏体的混合。根管锉在使用过程中受力弯曲变形时，其内部的马氏体会发生自协作孪晶亚结构的再取向，形成单一取向的孪晶结构，同时根管锉表现出大变形，如图4中的(a)所示。由于这种根管锉的屈服应力较低，因而具有很好的柔顺性，可以柔顺的到达根管尖部，并对根管尖部进行很好的清理；又由于其变形机制是以自协作马氏体孪晶的再取向过程为主，在反复的变形过程中不产生晶体缺陷，因而热激活镍钛合金根管锉的抗弯曲疲劳寿命大大增加。但由于该类根管锉的内部组织为热马氏体、或热马氏体和奥氏体的混合，因而强度较低，切削性能力也较差，尤其对根管的中部和上部这些切削量大的部位的清除，极为困难。
发明内容
为了解决现有技术中的问题，本发明提供了一种镍钛合金梯度柔性根管锉及其制造方法。
本发明提供了一种镍钛合金梯度柔性根管锉，包括工作部、柄部和定位环，所述工作部与所述柄部连接，所述工作部包括尖端段、过渡段和靠近所述柄部的根部段，所述定位环设置在所述工作部的根部段上。从所述尖端段的尖端开始,沿所述镍钛合金梯度柔性根管锉的长度方向至根部段，所述镍钛合金梯度柔性根管锉上各点的马氏体向奥氏体转变的相变终了温度Af逐步降低。
作为本发明的进一步改进，所述尖端段的长度为L1，所述过渡段的长度为L2，所述根部段的长度为L3，其中，所述尖端段的马氏体向奥氏体转变的相变终了温度Af高于或等于37℃，所述根部段的马氏体向奥氏体转变的相变终了温度Af低于37℃。
作为本发明的进一步改进，所述尖端段为马氏体、或马氏体和奥氏体的混合，所述根部段为全奥氏体。
作为本发明的进一步改进，L1为1-9毫米，L2为2-5毫米。
作为本发明的进一步改进，所述尖端段的马氏体向奥氏体转变的相变终了温度Af为37-65℃，所述根部段的马氏体向奥氏体转变的相变终了温度Af为0-30℃。
本发明还提供了一种镍钛合金梯度柔性根管锉的制造方法,包括以下步骤：
S1、镍钛合金材料经过冷拔和校直退火处理后，获得制造梯度柔性根管锉的原材料；
S2、由上述的原材料制备成一定长度的根管锉坯料；
S3、由根管锉坯料在柔性梯度化处理装置中进行柔性梯度化处理，制备成具有梯度柔性的根管锉坯料；
S4、具有梯度柔性的根管锉坯料经过机械成型加工，制备出具有梯度柔性的根管锉针；
S5、具有梯度柔性的根管锉针经柄部、定位环的安装，形成了镍钛合金梯度柔性根管锉。
作为本发明的进一步改进，所述的镍钛合金材料经过冷拔和校直退火处理，冷拔变形量为35-45％，退火温度为450-600℃，退火时间为30-120分钟，处理后镍钛合金材料的马氏体向奥氏体转变的相变终了温度Af为0-30℃。
作为本发明的进一步改进，所述的柔性梯度化处理装置包括导热体、电加热体和保温体，在所述导热体上开有孔，根管锉坯料的尖部插入孔中，在导热体的下部紧贴安装该电加热体，保温体将加热体和导热体的下半部分包围，而在导热体的上半部分则没有保温体的包围，在导热体内可以形成自下而上的梯度温度场。
作为本发明的进一步改进，所述的柔性梯度化处理装置通过控制加热体的加热温度、导热体的高度、根管锉坯料插入孔的深度、加热时间，来实现对根管锉坯料尖部相变温度的精确控制，根管锉坯料的尖部的马氏体向奥氏体转变的相变终了温度Af为37-65℃。
本发明还提供了，一种镍钛合金梯度柔性根管锉的制造方法,镍钛合金材料经过冷拔和校直退火处理后，先机械成型加工成根管锉针，成型后的根管锉针插入柔性梯度化处理装置中进行处理，制备出梯度柔性化的根管锉针；再经过柄部的定位环的安装，形成了镍钛合金梯度柔性根管锉。
本发明的有益效果是：同时具有好的切削性能、好的柔顺性能和高的抗疲劳断裂性能，从根本上改善现有镍钛合金根管锉存在的不足，以大大提高根管锉的使用性、安全性和寿命。
附图说明
图1、根管锉的结构图。
图2、根管锉的工作原理图。
图3、镍钛合金中热马氏体相变示意图。
图4、马氏体(a)、奥氏体(b)内部结构及其变形示意图。
图5、镍钛合金屈服应力与变形温度关系示意图。
图6、冷变形镍钛合金相变温度与退火温度关系示意图。
图7、镍钛合金相变温度与时效温度关系示意图。
图8、一种镍钛合金梯度柔性根管锉的示意图。
图9、根管锉坯料与柔性梯度化处理装置的示意图。
图10、根管锉坯料与根管锉针的示意图。
图11、根管锉针与柔性梯度化处理装置示意图。
具体实施方式
下面结合附图说明及具体实施方式对本发明进一步说明。
本发明提出了一种镍钛合金梯度柔性根管锉及其制造方法，从根本上改善现有镍钛合金根管锉存在的不足，以大大提高根管锉的使用性、安全性和寿命。
镍钛合金的相变温度，可通过多种手段进行控制与调节。冷变形对镍钛合金的相变温度有一定的影响。合金经冷变形后，组织中会产生大量的位错等晶体缺陷，导致合金的强度增加，合金中马氏体与奥氏体之间的相变阻力增加，使合金的相变困难，相变温度降低。冷变形的合金在经过退火处理后，冷变形组织会发生回复，其中的位错等晶体缺陷密度会降低，导致合金的强度降低，合金的相变温度升高。图6是Ti-50.6at％Ni合金经过30％的冷变形后，在不同温度下退火1小时后，其相变温度随退火温度的变化规律。
镍钛合金的基体成分对合金的相变温度有着显着的影响。实用的镍钛合金成分一般在Ti-49.8at％Ni到Ti-51.2at％Ni(原子比)的范围。镍钛合金的相变温度(如As、Af、Ms、Mf等)由合金基体中的Ni元素的含量决定的。合金基体中的Ni含量越高，合金的相变温度越低。研究表明，镍钛合金中的Ni含量每增加0.1at％(原子比)，合金是Ms温度降低12℃。高Ni的镍钛合金在时效热处理时有第二相析出，析出相为Ti3Ni4相。在Ti3Ni4相析出的同时，合金基体的Ni含量降低，合金的相变温度会随之升高。图7是Ti-50.6at％Ni合金经完全固溶处理后，在不同温度下时效1小时后，合金的相变温度随时效温度的变化规律。
如前所述，理想的镍钛合金根管锉至少需要同时满足三方面的性能，好的切削性能、好的柔顺性能和高的抗疲劳断裂性能，而上述三种性能是彼此矛盾的。好的切削性能意味着根管锉需要有较高的强度，而好的柔顺性能又要求根管锉的强度不能太高，高的抗弯曲疲劳断裂寿命又需要根管锉的内部组织为马氏体或马氏体与奥氏体的混合。这对于具有单一相变温度的镍钛合金的根管锉，是不可能实现的。如已 经公开的超弹性镍钛合金根管锉，其合金的Af温度低于37℃，既根管锉各点材料具有相同的相变温度，且各点的Af温度都低于37℃。该种根管锉虽具有好的切削性能，但在根管锉的尖部易发生断裂，导致其使用安全性低下。已经公开的镍钛合金热激活根管锉，其合金的Af温度高于37℃，既根管锉各点材料具有相同的相变温度，且各点的Af温度都高于37℃。该种根管锉虽具有良好的柔顺性和很好的抗弯曲疲劳断裂寿命，但由于合金的强度较低，其切削能力低下，尤其是对根管中部和上部的切削量大的部位的清除，极为困难，造成该种根管锉的使用性能低下。
为了解决上述镍钛合金根管锉的不足，本发明提出了一种镍钛合金梯度柔性根管锉及其制造方法。
如图8所示，本发明涉及一种镍钛合金梯度柔性根管锉,包括工作部1、柄部2和定位环3，所述工作部1与所述柄部2连接，所述工作部1包括尖端段11、过渡段12和靠近所述柄部2的根部段13，所述定位环3设置在所述工作部1的根部段13上，从所述尖端段11的尖端开始,沿所述镍钛合金梯度柔性根管锉的长度方向至根部段13，所述镍钛合金梯度柔性根管锉上各点的马氏体向奥氏体转变的相变终了温度Af逐步降低。
马氏体向奥氏体转变的相变终了温度Af又可简称为Af温度。
如图8所示，所述尖端段11的长度为L1，所述过渡段12的长度为L2，所述根部段13的长度为L3，其中，所述尖端段11的马氏体向奥氏体转变的相变终了温度Af高于或等于37℃，所述根部段13的马氏体向奥氏体转变的相变终了温度Af低于37℃。
如图8所示，所述尖端段11为马氏体或马氏体和奥氏体的混合，所述根部段13为全奥氏体。
如图8所示，L1为优选1-9毫米，L1可优选为1毫米、2毫米、3毫米、4毫米、5毫米、6毫米、7毫米、8毫米、9毫米中的任意一个，L2优选为2-5毫米，L2可优选为2毫米、3毫米、4毫米、5毫米中的任意一个。
如图8所示，所述尖端段11的马氏体向奥氏体转变的相变终了温度Af优选为37-65℃，所述尖端段11的马氏体向奥氏体转变的相 变终了温度Af可优选为37℃、40℃、45℃、50℃、55℃、60℃、65℃中的任意一个，所述根部段13的马氏体向奥氏体转变的相变终了温度Af优选为0-30℃，所述根部段13的马氏体向奥氏体转变的相变终了温度Af可优选为0℃、5℃、10℃、15℃、20℃、25℃、30℃中的任意一个。
在37℃温度环境下，尖端段11内的组织为马氏体或马氏体和奥氏体的混合，根部段13的组织为全奥氏体组织。由于该镍钛合金梯度柔性根管锉的内部组织是渐变的，沿根管锉轴向方向，其强度也是渐进变化的，如图5所示。
在镍钛合金梯度柔性根管锉的尖端段11，由于内部组织是马氏体或马氏体和奥氏体的混合，因而该段的强度较低，具有极好的柔顺性，可以顺利的到达根管尖部并对根管尖部进行很好的清理。又由于尖端段11的变形机制是以自协作马氏体孪晶的再取向过程为主，在反复的变形过程中不产生晶体缺陷，因而尖端段11具有极高的抗弯曲疲劳寿命，大大降低了根管锉尖部断裂的风险，如图4和图5所示。
在镍钛合金梯度柔性根管锉的根部段13内，合金中组织为全奥氏体组织，变形机制以应力诱发马氏体相变的方式进行，该段的合金强度较高，因而具有良好的切削性能，但根部段13的柔顺性较L1段的要差，如图4和图5所示。
由于该镍钛合金梯度柔性根管锉的内部组织沿轴向是渐变的，因而其柔性和强度沿根管锉的轴向表现出梯度变化的特征。
本发明还提供了一种镍钛合金梯度柔性根管锉的制造方法。镍钛合金梯度柔性根管锉的制造是这样实现的：采用的合金的成分范围一般选择在Ti-50.2at％Ni到Ti-51.2at％Ni(原子比)的范围。为了提高合金的强度，合金需要进行冷拔处理制备成一定直径的丝材，冷拔的变形量应该在35-45％的范围。经冷拔的合金丝材再经过450-600℃、30-120分钟的退火校直处理，作为制造梯度柔性根管锉的原材料。镍钛合金丝材的Af温度被控制在0-30℃范围内，如图6和图7所描述，对于冷变形的和高镍的镍钛合金，可以通过控制退火或时效温度和时间，对镍钛合金的相变温度加以控制与调整。
一种镍钛合金梯度柔性根管锉的制造方法是，先将上述原材料机 械加工成一定长度的根管锉坯料5，对该根管锉坯料5进行柔性梯度化处理，如图9。柔性梯度化处理装置由导热体6、电加热体7和保温体8构成，在导热体上开有孔9，根管锉坯料5的尖部插入孔9中。在导热体6的下部紧贴安装有电加热体7，保温体8将加热体7和导热体6的下半部分包围，防止热量从下方散失；而在导热体6的上半部分则没有保温体的包围，热量可以从导热体6的上半部散失，如此便可以在导热体6内形成自下而上的梯度温度场。由于热传导效应，插在孔9中的根管锉坯料5被加热，根管锉坯料5被加热的温度沿轴向自下而上也是呈梯度分布的。由于根管锉坯料5从尖端开始沿轴向自下而上，受到的加热温度逐渐升高，因而导致根管锉坯料5的中在组织自尖端开始向上逐步变化。
在柔性梯度化处理时，根管锉坯料5的尖端段11内会发生冷变形组织的再回复和Ti3Ni4相的析出，如图6和图7中所描述的。冷变形组织在加热时会发生回复，导致组织中晶体缺陷减少，使合金相变温度升高；高Ni的镍钛合金在时效热处理时有相Ti3Ni4析出，使得合金基体的Ni含量降低，合金的相变温度会随之升高。在上述双重作用下，根管锉坯料5的尖部的Af温度升高。又由于根管锉坯料5自下而上受到的温度是梯度变化的，所以根管锉坯料5的尖端部11和过渡段12中的组织变化也是随温度梯度而渐变的，从而实现了根管锉坯料5的柔性和强度沿轴向表现出梯度变化的特征。根部段13由于在柔性梯度化处理过程中不被加热，因而该段的Af温度没有变化，依然保持原材料的Af温度，既0-30℃。
通过控制加热体7的加热温度、导热体6的高度、根管锉坯料5插入孔9的深度、加热时间等工艺参数，可以实现对根管锉坯料5尖部相变温度精确控制。根管锉坯料5尖端的Af温度应被控制在37-65℃范围。
柔性梯度化处理后的根管锉坯料5经机械加工成型，得到所要求的根管锉针10，如图10所示。根管锉针10再经过柄部2和定位环3的安装，形成了本发明说述的镍钛合金梯度柔性根管锉。
本发明涉及的一种镍钛合金梯度柔性根管锉,尖端段11的Af温度为37-65℃，根部段13的Af温度为0-30℃。
本发明还提供了另外一种镍钛合金梯度柔性根管锉的制造方法，将成分范围在Ti-50.2at％Ni到Ti-51.2at％Ni(原子比)的合金进行冷拔处理，制备成一定直径的丝材，冷拔的变形量应该在35-45％的范围。经冷拔的合金丝材再经过450-600℃、30-120分钟的退火校直处理，然后经机械成型加工成根管锉针10。加工成型后的根管锉针10插入图9所示的柔性梯度化处理装置中进行柔性梯度化处理，如图11。经柔性梯度化处理的根管锉针10再经过柄部2和定位环3的安装，形成了本发明所述的镍钛合金梯度柔性根管锉。
以上内容是结合具体的优选实施方式对本发明所作的进一步详细说明，不能认定本发明的具体实施只局限于这些说明。对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单推演或替换，都应当视为属于本发明的保护范围。

Claims (10)

  1. 一种镍钛合金梯度柔性根管锉，包括工作部、柄部和定位环，所述工作部与所述柄部连接，所述工作部包括尖端段、过渡段和靠近所述柄部的根部段，所述定位环设置在所述工作部的根部段上，其特征在于：从所述尖端段的尖端开始,沿所述镍钛合金梯度柔性根管锉的长度方向至根部段，所述镍钛合金梯度柔性根管锉上各点的马氏体向奥氏体转变的相变终了温度Af逐步降低。
  2. 根据权利要求1所述的镍钛合金梯度柔性根管锉，其特征在于：所述尖端段的长度为L1，所述过渡段的长度为L2，所述根部段的长度为L3，其中，所述尖端段的马氏体向奥氏体转变的相变终了温度Af高于或等于37℃，所述根部段的马氏体向奥氏体转变的相变终了温度Af低于37℃。
  3. 根据权利要求2所述的镍钛合金梯度柔性根管锉，其特征在于：所述尖端段为马氏体或马氏体和奥氏体的混合，所述根部段为全奥氏体。
  4. 根据权利要求2所述的镍钛合金梯度柔性根管锉，其特征在于：L1为1-9毫米，L2为2-5毫米。
  5. 根据权利要求2所述的镍钛合金梯度柔性根管锉，其特征在于：所述尖端段的马氏体向奥氏体转变的相变终了温度Af为37-65℃，所述根部段的马氏体向奥氏体转变的相变终了温度Af为0-30℃。
  6. 一种镍钛合金梯度柔性根管锉的制造方法,其特征在于，包括以下步骤：
    S1、镍钛合金材料经过冷拔和校直退火处理后，获得制造梯度柔性根管锉的原材料；
    S2、由上述的原材料制备成一定长度的根管锉坯料；
    S3、由根管锉坯料在柔性梯度化处理装置中进行柔性梯度化处理，制备成具有梯度柔性的根管锉坯料；
    S4、具有梯度柔性的根管锉坯料经过机械成型加工，制备出具有梯度柔性的根管锉针；
    S5、具有梯度柔性的根管锉针经柄部、定位环的安装，形成了镍钛合金梯度柔性根管锉。
  7. 根据权利要求6所述的镍钛合金梯度柔性根管锉的制造方法,其特征在于：所述的镍钛合金材料经过冷拔和校直退火处理，冷拔变形量为35-45％，退火温度为450-600℃，退火时间为30-120分钟，处理后镍钛合金材料的马氏体向奥氏体转变的相变终了温度Af为0-30℃。
  8. 根据权利要求6所述的镍钛合金梯度柔性根管锉的制造方法,其特征在于：所述的柔性梯度化处理装置包括导热体、电加热体和保温体，在所述导热体上开有孔，根管锉坯料的尖部插入孔中，在导热体的下部紧贴安装该电加热体，保温体将加热体和导热体的下半部分包围，而在导热体的上半部分则没有保温体的包围，在导热体内可以形成自下而上的梯度温度场。
  9. 根据权利要求8所述的镍钛合金梯度柔性根管锉的制造方法,其特征在于：所述的柔性梯度化处理装置通过控制加热体的加热温度、导热体的高度、根管锉坯料插入孔的深度、加热时间，来实现对根管锉坯料尖部相变温度的精确控制，根管锉坯料的尖部的马氏体向奥氏体转变的相变终了温度Af为37-65℃。
  10. 一种镍钛合金梯度柔性根管锉的制造方法,其特征在于，镍钛合金材料经过冷拔和校直退火处理后，先机械成型加工成根管锉针，成型后的根管锉针插入柔性梯度化处理装置中进行处理，制备出梯度柔性化的根管锉针；再经过柄部的定位环的安装，形成了镍钛合金梯度柔性根管锉。
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