A method for preparing titanium alloy rods for ultrasonic scalpels

Abstract

This invention relates to the field of medical titanium and titanium alloy material preparation technology, and provides a method for preparing titanium alloy rods for ultrasonic scalpels. The method includes: mixing raw materials containing titanium, aluminum, and vanadium and pressing them into electrodes; vacuum melting to obtain an ingot; the chemical composition of the ingot, by weight percentage, includes Al: 6.10~6.60%, V: 3.60~4.10%, O: 0.08~0.14%, Fe≤0.10%, with the balance being Ti and unavoidable impurities; forging the ingot and performing at least two upsetting and drawing reversal processes to obtain a square billet; hot continuous rolling the square billet to obtain coiled wire; and performing low-temperature heat treatment on the rod obtained from the coiled wire in a vacuum environment. This invention optimizes the material's microstructure through synergistic control of composition and process, significantly improving ultrasonic energy transmission efficiency, resulting in an ultrasonic scalpel rod that possesses both excellent cutting speed and hemostatic effect.

Description

Technical Field

[0001] This invention relates to the field of medical titanium and titanium alloy material preparation technology, specifically to a method for preparing titanium alloy rods for ultrasonic scalpels. Background Technology

[0002] An ultrasonic scalpel is a precision medical instrument that uses ultrasonic energy to cut and stop bleeding in biological tissues. Its core working principle involves a piezoelectric ceramic plate within the handle converting electrical energy into mechanical energy, generating longitudinal mechanical vibration. This vibration is transmitted through the scalpel shaft to the scalpel head, causing the scalpel head to contact the tissue proteins and generate high-frequency vibrations. This leads to the breaking of protein hydrogen bonds, structural remodeling, and vascular coagulation and closure. In this energy transmission process, the scalpel shaft, as the key transmission medium, has material properties such as density, elastic modulus, and Poisson's ratio that directly determine the ultrasonic energy transmission efficiency, vibration acceleration, and thermal conversion efficiency, thus affecting the cutting speed and hemostasis effect during surgery.

[0003] Currently, domestically produced ultrasonic scalpel rods are typically manufactured using TC4ELI titanium alloy rods conforming to the national standard (GB / T 13810-2017). However, existing domestically produced TC4ELI titanium alloy rods mainly follow general industrial or medical-grade standards in terms of chemical composition control, processing technology, and heat treatment, without targeted optimization for the specific needs of ultrasonic energy transmission. This results in scalpel rods made from existing domestic materials exhibiting problems such as high ultrasonic energy transmission loss, insufficient vibration acceleration, and low thermal conversion efficiency in clinical applications. Specifically, this manifests as slower cutting speed and poor hemostasis, showing a significant gap compared to imported products of the same type. Therefore, there is an urgent need to develop a method for preparing titanium alloy rods for ultrasonic scalpels that can significantly improve ultrasonic energy transmission efficiency while maintaining excellent cutting speed and hemostasis. Summary of the Invention

[0004] To address the problems of low ultrasonic energy transmission efficiency and insufficient cutting and hemostasis performance of domestically produced titanium alloy rods for ultrasonic scalpels in existing technologies, this application proposes a method for preparing titanium alloy rods for ultrasonic scalpels, which achieves directional control of material composition and microstructure, thereby significantly improving the cutting speed and hemostasis effect of ultrasonic scalpels.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing titanium alloy rods for ultrasonic scalpels includes the following steps: Smelting: Mixing raw materials containing titanium, aluminum, and vanadium and pressing them into electrodes, then vacuum smelting to obtain an ingot; the chemical composition of the ingot, by weight percentage, includes: Al: 6.10~6.60%, V: 3.60~4.10%, O: 0.08~0.14%, Fe≤0.10%, with the balance being Ti and unavoidable impurities; Forging: Forging the ingot, and performing at least two upsetting and drawing reversal operations to obtain a billet; Rolling: Hot continuous rolling the billet to obtain coiled wire; Heat treatment: Performing low-temperature heat treatment on the rod obtained from the coiled wire in a vacuum environment to obtain the titanium alloy rod for ultrasonic scalpels.

[0006] In one embodiment, the chemical composition of the ingot, by weight percentage, includes: Al: 6.20~6.50%, V: 3.70~4.0%, O: 0.10~0.13%, Fe<0.1%, N<0.05%, C<0.05%, and the content of other impurities is less than 0.1%; the pressed electrode comprises: continuously and integrally pressing the raw material using a hydraulic press to obtain the electrode with a density of 3.8~4.2 g / cm³.

[0007] In one embodiment, the vacuum melting includes: performing three vacuum melting processes, with the diameter of the resulting ingots increasing sequentially; wherein the diameter of the ingot obtained from the first melting process is 550-600 mm, the diameter of the ingot obtained from the second melting process is 620-660 mm, and the diameter of the ingot obtained from the third melting process is 700-750 mm.

[0008] In one embodiment, the forging is a multi-fire upsetting and reversing forging, which includes: initial forging: performed at a heating temperature of 1100~1150℃; intermediate upsetting and reversing forging: performed at least two upsetting and reversing operations at a heating temperature of 950~1100℃; and final forging: forging into a square billet with a cross-sectional size of 140×140mm to 160×160mm.

[0009] In one embodiment, the intermediate upsetting and reversing forging includes a first heating cycle, a second heating cycle, and a third heating cycle performed sequentially, with the heating temperature decreasing sequentially; the hot continuous rolling includes rolling at a heating temperature of 930~960℃, with supplemental heating during the rolling process to ensure that the final rolling temperature is not lower than 850℃, and rapid water cooling after rolling.

[0010] As one embodiment, the low-temperature heat treatment includes: heat preservation treatment of the bar material at a temperature of 550~750°C in a vacuum heat treatment furnace with a vacuum degree of 10⁻³Pa or higher; during the heat preservation treatment, the bar material is tightly arranged in an anti-deformation fixture to limit the deformation of the bar material.

[0011] As one implementation method, the heat preservation treatment includes setting a heating step for heat preservation; after the low-temperature heat treatment, the microstructure of the titanium alloy rod for ultrasonic scalpel meets the following conditions: average grain size is 2~3μm; volume ratio of α phase is ≥96%; texture strength is ≥5.0.

[0012] In addition, the present invention also provides a titanium alloy rod for ultrasonic scalpels, which is prepared by the method for preparing titanium alloy rods for ultrasonic scalpels as described above; the microstructure of the titanium alloy rod for ultrasonic scalpels satisfies the following: the average grain size is 2~3μm, the volume ratio of α phase is ≥96%, and the texture strength is ≥5.0.

[0013] In addition, the present invention also provides an ultrasonic scalpel handle, including a handle body, the handle body being machined from a titanium alloy rod material for ultrasonic scalpels as described above; the handle body includes a hook-shaped working end, a straight shaft and a connecting end connected in sequence, the connecting end being provided with a transverse through mounting hole.

[0014] Furthermore, the present invention also provides an ultrasonic scalpel system, including an ultrasonic main unit, a handle, and an ultrasonic scalpel shaft as described above; the ultrasonic main unit is electrically connected to the handle, and the handle is mechanically connected to the ultrasonic scalpel shaft; the ultrasonic main unit is configured to transmit ultrasonic energy to the ultrasonic scalpel shaft through the handle. Beneficial effects

[0015] 1. This invention optimizes the chemical composition of TC4ELI titanium alloy, particularly by controlling the V content within a narrow range of 3.60~4.10% and the Fe content within a narrow range of ≤0.10%, effectively reducing the overall density of the alloy. According to the principles of acoustic transmission, reducing material density helps increase the propagation speed and natural frequency of ultrasound waves in the medium, reducing inertial loss during transmission. Simultaneously, strictly controlling the content of interstitial impurity elements such as O, N, and C reduces lattice distortion and phonon scattering centers, fundamentally improving the purity of ultrasonic energy transmission and laying the material foundation for solving the problem of slow cutting speed.

[0016] 2. This invention employs a forging process involving at least two upsetting and drawing reversals, combined with hot continuous rolling within a specific temperature range and rapid water cooling, to achieve thorough fragmentation and recrystallization refinement of the as-cast microstructure. The multi-stage upsetting and drawing reversal effectively eliminates casting segregation and coarse grains, resulting in a more homogenized microstructure. The large deformation during hot continuous rolling further refines the grain size, while rapid water cooling suppresses grain growth at high temperatures. This synergistic thermomechanical treatment process ensures that the final bar has a fine, uniform equiaxed grain structure, significantly reducing ultrasonic wave scattering at grain boundaries and improving the continuity of energy transmission.

[0017] 3. This invention precisely controls the two-phase ratio, texture strength, and residual stress state of the material through low-temperature heat treatment in a vacuum environment, combined with anti-deformation tooling constraints. Low-temperature annealing at 550~750℃ avoids grain coarsening and eliminates internal stress caused by work hardening, reducing the nonlinear attenuation of acoustic waves due to residual stress. A specific stepped heating and holding regime promotes the stable precipitation and preferred orientation of the α phase, resulting in a microstructure with high texture strength (≥5.0) and a high α phase ratio (≥96%). This highly ordered crystallographic texture matches the direction of ultrasonic vibration, greatly improving the transmission efficiency of longitudinal mechanical vibration. This allows the tool holder to achieve higher vibration acceleration and better thermal conversion efficiency under the same input power, thus achieving a dual improvement in cutting speed and hemostasis effect, making its performance reach or even surpass that of imported similar products.

[0018] 4. This invention constructs a complete protection chain from raw material preparation to the final complete system. By providing titanium alloy rods with specific microstructure characteristics, ultrasonic scalpel handles processed from these rods, and ultrasonic scalpel systems incorporating these handles, it achieves comprehensive coverage of the technological achievement across the entire industry chain. This not only safeguards the rights and interests of the core material preparation methods but also provides a solid technological barrier and legal basis for market competition in downstream medical device products. Attached Figure Description

[0019] Figure 1 This is a data table of chemical composition analysis of titanium alloy rods for ultrasonic scalpels according to an embodiment of the present invention; Figure 2 This is a metallographic image of the billet microstructure according to an embodiment of the present invention; Figure 3 This is a microstructure diagram of the hot-rolled coiled wire according to an embodiment of the present invention; Figure 4 This is a microstructure image of the finished bar stock according to an embodiment of the present invention; Figure 5 These are microstructure and phase distribution diagrams of the heat-treated bar stock according to an embodiment of the present invention. Figure 6 These are microstructure and texture characterization images of titanium alloys according to embodiments of the present invention; Figure 7 This is a schematic diagram of the ultrasonic surgical scalpel shaft structure according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the manufacturing process of the ultrasonic surgical scalpel shaft according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Example

[0022] This embodiment provides a method for preparing titanium alloy rods for ultrasonic scalpels. This method focuses on targeted optimization of ultrasonic energy transmission efficiency, differing from the commonly used TC4ELI titanium alloy preparation process. Specifically, this invention aims to obtain a microstructure with high ultrasonic transmission efficiency through synergistic control of composition design, thermomechanical treatment, and heat treatment. The preparation method includes the following steps: Step S100, Melting: Raw materials containing titanium, aluminum, and vanadium are mixed and pressed into electrodes, then vacuum melted to obtain an ingot. The chemical composition of the ingot, by weight percentage, includes: Al: 6.10~6.60%, V: 3.60~4.10%, O: 0.08~0.14%, Fe≤0.10%, with the balance being Ti and unavoidable impurities. Specifically, this melting step is not only to obtain a titanium alloy ingot that meets medical standards, but more importantly, to optimize the acoustic performance of the material from the source through the aforementioned specific narrow-range composition design. For example, by controlling the content of V and Fe elements at low levels, the overall density of the alloy can be effectively reduced, thereby reducing the inertial loss of ultrasound waves propagating in the medium and increasing the natural frequency of the material; at the same time, strictly controlling the content of interstitial elements such as O can reduce lattice distortion and phonon scattering centers, improving the purity of ultrasound energy transmission. It should be understood that although this embodiment provides a specific composition range, in other embodiments, as long as the functional requirements of reducing density and reducing phonon scattering are met, the specific ratio of each element can be flexibly adjusted within the above range.

[0023] Step S200, Forging: The ingot is forged, with at least two upsetting and drawing reversal operations to obtain a square billet. Specifically, the core function of the forging step is to fully break down the as-cast microstructure and eliminate compositional segregation. Through at least two upsetting and drawing reversal operations, coarse grains and columnar crystals inside the ingot can be effectively broken down, promoting microstructure homogenization and laying a good microstructure foundation for subsequent processing. This multi-directional deformation method can effectively eliminate the deformation dead zone that may be generated by unidirectional forging, ensuring that the final bar has relatively consistent mechanical properties and acoustic response characteristics in all directions.

[0024] Step S300, Rolling: The billet is hot-rolled to obtain coiled wire. Specifically, the hot rolling step utilizes a large deformation to further refine the grain size and make the microstructure more dense and uniform. Compared with traditional free forging or open rolling, hot rolling can provide a more continuous and uniform deformation field, which is conducive to the formation of fine equiaxed grain structures, thereby reducing the scattering attenuation of ultrasonic waves at grain boundaries and improving the continuity of energy transmission.

[0025] Step S400, Heat Treatment: The rod obtained from the coiled wire is subjected to low-temperature heat treatment in a vacuum environment to obtain a titanium alloy rod for ultrasonic scalpels. Specifically, this heat treatment step is not a simple stress-relieving annealing, but a refined microstructure control specifically for ultrasonic transmission performance. Low-temperature treatment in a vacuum environment avoids grain coarsening caused by high temperatures, maintaining the fine-grained microstructure obtained in previous processes; it also allows for precise control of the ratio of α-phase to β-phase and the crystallographic texture, eliminating the influence of residual stress on the nonlinear attenuation of sound waves. Through the synergistic effect of these steps, the titanium alloy rod prepared by this invention can significantly improve the transmission efficiency of ultrasonic energy while ensuring biocompatibility, enabling the ultrasonic scalpel rod processed from it to possess excellent cutting speed and hemostatic effect. Example

[0026] This embodiment, based on Embodiment 1, further optimizes the chemical composition control and smelting process in the melting step to establish a strong correlation between compositional purity and acoustic performance. Specifically, the chemical composition of the ingot, by weight percentage, includes: Al: 6.20~6.50%, V: 3.70~4.0%, O: 0.10~0.13%, Fe <0.1%, N <0.05%, C <0.05%, and other impurities less than 0.1%. Compared to the wider composition range in Embodiment 1, this embodiment further narrows the content window of key elements. Specifically, the V content is strictly limited to 3.70~4.0%, and the Fe content is limited to below 0.1%, with the core objective of reducing the overall density of the alloy. According to the theory of sound wave propagation, reducing material density is beneficial for increasing the propagation speed and natural frequency of ultrasound in the medium, and reducing inertial loss during sound wave transmission. Simultaneously, controlling interstitial elements such as O, N, and C to extremely low levels can effectively reduce lattice distortion and phonon scattering centers in titanium alloys, purifying the lattice structure at the atomic scale, thereby significantly improving the purity of ultrasonic energy transmission. It should be understood that although this embodiment provides a preferred narrow range, in other embodiments, as long as the content of each element falls within the wide range described in Example 1 and meets the ultrasonic transmission performance requirements, it falls within the protection scope of this invention.

[0027] In the electrode preparation stage, the pressing of the electrode involves continuously and integrally pressing the raw material using a hydraulic press to obtain an electrode with a density of 3.8~4.2 g / cm³. Specifically, traditional processes often use tungsten electrode welding to connect electrode blocks, which easily introduces high-density defects such as tungsten inclusions during the melting process, becoming obstacles to ultrasonic transmission. This embodiment uses a continuous integral pressing process, which not only avoids the risk of foreign inclusions caused by welding, but also ensures that the internal porosity of the electrode is moderate and uniformly distributed by controlling the electrode density within the range of 3.8~4.2 g / cm³. This facilitates the smooth discharge of gas and the stable formation of the molten pool during vacuum melting, thereby further improving the metallurgical quality of the ingot.

[0028] To obtain ingots with highly homogeneous composition, vacuum melting involves three stages of melting, with the diameter of the resulting ingots increasing sequentially. The diameter of the ingot obtained from the first melting is 550-600 mm, from the second melting is 620-660 mm, and from the third melting is 700-750 mm. This progressively increasing melting strategy is not simply repeated melting but has a specific metallurgical purpose. The first melting primarily completes the preliminary alloying and degassing of the raw materials; the second melting, by increasing the ingot size and utilizing a larger molten pool volume, promotes macroscopic homogenization of composition and further removes low-melting-point volatile impurities; the third melting, at the largest ingot size, achieves final refining and solidification structure control, completely eliminating compositional segregation and microscopic defects. Figure 1 As shown, after the above three vacuum melting processes, the chemical composition test results of the upper and lower parts of the ingot were consistently within the target narrow range (e.g., Al content was 6.34% and 6.40%, and V content was 3.86% and 3.82%, respectively), proving the effectiveness of this melting strategy in ensuring compositional consistency and purity.

[0029] To verify the substantial impact of the aforementioned narrow-range composition design on ultrasonic performance, this embodiment also includes examples of composition endpoint values ​​and comparative examples outside the boundary. In the endpoint value examples, when the Al content is 6.10% or 6.60% and the V content is 3.60% or 4.10%, the prepared rod can still maintain a qualified ultrasonic transmission efficiency, indicating that the wide-range boundary has good process robustness. However, when the composition exceeds the range defined by this invention, the performance will deteriorate significantly. For example, in Comparative Example A, increasing the V content to 4.2% leads to an increase in alloy density due to the excessive addition of V as a high-density β-stabilizing element, and the measured average cutting time of the ultrasonic scalpel rod is extended by about 15%. In Comparative Example B, increasing the Fe content to 0.12% results in the formation of iron-rich phase segregation due to the excessive Fe element, which increases the sound wave scattering loss, leading to a decrease in cutting efficiency and unstable hemostasis effect. These comparative results, in turn, confirm the necessity of optimizing acoustic performance by precisely controlling the content of key elements such as V and Fe, and also demonstrate that the range of components is not arbitrarily chosen, but rather a key window for achieving excellent ultrasonic transmission effects, derived from extensive experimental verification. Example

[0030] This embodiment, based on Embodiment 1, further specifies the specific parameters and synergistic control strategies for the forging and rolling processes to achieve refined control of the microstructure of the titanium alloy bar. Specifically, the forging is a multi-fire upsetting and reversing forging, which includes: initial forging: performed at a heating temperature of 1100~1150℃; intermediate upsetting and reversing forging: performed at least twice at a heating temperature of 950~1100℃; and final forging: forging into a square billet with a cross-sectional size of 140×140mm to 160×160mm.

[0031] In the aforementioned forging process, the temperature settings and deformation methods at each stage have clear metallurgical objectives. The initial forging is performed in the high-temperature range of 1100–1150°C to utilize the good plasticity and low deformation resistance of titanium alloys at this temperature, effectively breaking down the coarse columnar grains and Widmanstätten structure in the as-cast microstructure, thus eliminating casting porosity and segregation. The subsequent intermediate upsetting and reversing forging is a crucial step in obtaining a uniform equiaxed grain structure. By performing at least two upsetting and reversing operations within the 950–1100°C range, not only can the deformation dead zone and texture anisotropy generated by unidirectional forging be effectively eliminated, but the grains can also be refined through repeated recrystallization. Preferably, the intermediate upsetting and reversing forging includes a first, second, and third heating cycle performed sequentially, with the heating temperature decreasing sequentially. This temperature-decreasing strategy avoids abnormal grain growth caused by prolonged high temperatures. Furthermore, as deformation accumulates and temperature decreases, the dislocation density and stored energy within the material gradually increase, providing sufficient driving force for recrystallization nucleation in subsequent heat treatment stages. For example, in one specific embodiment, the first heating temperature is 1100℃, the second is reduced to 1050℃, and the third is further reduced to 970℃, with each heating cycle involving three upsetting and three drawing operations. The final forging process shapes the billet into a square billet with a cross-sectional size of 140×140mm to 160×160mm. This size range ensures a sufficient compression ratio to maintain a dense core structure and provides suitable raw material specifications for subsequent hot continuous rolling. Figure 2 As shown, the microstructure of the billet after the above-mentioned multi-fire upsetting and drawing reversal forging shows that the grains are fine and uniformly distributed, with no obvious undeformed areas or coarse grain bands, proving the effectiveness of this forging process in achieving microstructure homogenization.

[0032] After obtaining a high-quality square billet, hot continuous rolling includes: rolling at a heating temperature of 930~960℃, with supplemental heating during rolling to ensure the final rolling temperature is not lower than 850℃, followed by rapid water cooling. The hot continuous rolling process inherits the fine-grained structure after forging, further refining the grain size through continuous large deformation. The heating temperature is controlled at 930~960℃ to ensure the material is within a suitable deformation window in the α+β two-phase region, balancing plasticity and microstructure stability. It is particularly important to emphasize that the supplemental heating measures during rolling and ensuring the final rolling temperature is not lower than 850℃ are key control points for ensuring consistent microstructure and properties in this invention. If the final rolling temperature is too low, the material enters a strong work-hardening zone, not only increasing the rolling load dramatically but also easily inducing local shear bands or mixed-grain structures; if the final rolling temperature is too high, it will cause the rapidly growing grains after dynamic recrystallization, negating the previous refining effect. Rapid water cooling after rolling is to suppress the transformation of metastable structures and static grain growth at high temperatures, "freezing" the fine deformed structure to room temperature. Figure 3As shown, the microstructure of the coiled wire after hot continuous rolling and rapid water cooling exhibits dense and uniform fine equiaxed crystal characteristics. The grain size is further refined compared to the billet stage, and the difference in microstructure between the inner and outer rings of the coil is minimal, verifying the effective control of microstructure inheritance by this process combination.

[0033] To verify the criticality of the above process parameters and their substantial impact on ultrasonic performance, the following comparative verification was also conducted in this embodiment. In the comparison of forging heats, when only two upsetting and drawing reversal processes were performed, although the macroscopic forming was satisfactory, metallographic examination revealed a slight, incompletely recrystallized, streamlined region in the core of the billet, causing the resonant frequency of the subsequently manufactured tool holder to drift during ultrasonic vibration testing. However, after using three progressively decreasing upsetting and drawing reversal processes, the microstructure uniformity was significantly improved, and the resonant frequency stability reached its optimal level. In the comparison of final rolling temperatures, when the final rolling temperature dropped to 840℃, microcracks appeared on the surface of the coiled wire due to entering the low-temperature, high-resistance zone, and the cross-sectional grain size difference exceeded level 2, severely affecting the material's fatigue life and ultrasonic transmission efficiency. However, when the final rolling temperature was strictly controlled at 850℃ or higher, the wire surface quality remained intact, and the grain size difference was controlled within level 0.5. These comparative results fully demonstrate that the "at least two upsetting and drawing reversals" and "final rolling temperature ≥850℃ + rapid water cooling" specified in this invention are not simply the superposition of process parameters, but rather a synergistic technical system built upon the hot deformation mechanism of titanium alloys and the requirements for ultrasonic transmission performance. This system plays an irreplaceable role in obtaining high-performance titanium alloy bars for ultrasonic scalpels. It should be understood that although this embodiment provides preferred heat treatment arrangements and temperature points, in actual production, as long as the above functional requirements and parameter ranges are met, the specific heating and holding times, pass reductions, etc., can be adaptively adjusted according to equipment capabilities, and all fall within the protection scope of this invention. Example

[0034] This embodiment, based on Embodiments 1 to 3, further defines the heat treatment process and the microstructure characteristics of the final product, which is a key step in achieving the high-performance transmission characteristics of titanium alloy rods for ultrasonic scalpels. Specifically, the low-temperature heat treatment includes: holding the rod at a temperature of 550~750°C in a vacuum heat treatment furnace with a vacuum degree of 10⁻³Pa or higher; during the holding treatment, the rod is tightly arranged in an anti-deformation fixture to limit the deformation of the rod.

[0035] In this embodiment, the selection of heat treatment temperature is crucial. 550–750°C is a typical low-temperature annealing window. This temperature range is below the recrystallization temperature of titanium alloys, effectively preventing the coarsening of the fine equiaxed grains obtained from previous hot rolling, while providing sufficient thermal activation energy to promote the rearrangement and annihilation of dislocations generated by work hardening, thereby eliminating residual stress. Eliminating residual stress is particularly critical for ultrasonic scalpel holders, as the internal stress field causes nonlinear attenuation and frequency drift of ultrasonic waves during transmission, directly affecting the cutting stability during surgery. Simultaneously, maintaining a vacuum level above 10⁻³ Pa prevents the titanium alloy from absorbing hydrogen and oxygen at high temperatures, leading to surface embrittlement or contamination, and ensures the biocompatibility and acoustic purity of the material.

[0036] It is particularly important to emphasize that this embodiment introduces the hardware constraint feature of anti-deformation fixtures. Since ultrasonic scalpel rods are typically slender rods with a large length-to-diameter ratio, they are highly susceptible to bending deformation during heat treatment heating and cooling due to their own weight or the release of thermal stress. If the straightness deviates from the tolerance, not only will subsequent machining be difficult, but the assembled ultrasonic scalpel system will also experience eccentric vibrations during resonance, significantly reducing energy transmission efficiency and even damaging the handle. Therefore, this invention requires that the rods be tightly arranged within the anti-deformation fixture. It should be understood that the specific form of the anti-deformation fixture is not limited to a particular structure, as long as it can provide continuous or discrete support along the axial direction of the rod and limit its radial displacement. For example, a graphite or ceramic bracket with a precision V-groove can be used, utilizing the self-centering effect of the V-surface to keep the rod straight; a porous clamping frame can also be used, applying a moderate preload to the rod through the cooperation of upper and lower pressure plates and locating pins; or a metal sleeve matching the outer diameter of the rod can be used for constraint. The synergistic effect of this physical constraint and low-temperature heat treatment ensures that the bar maintains excellent straightness while relieving stress, laying the geometric foundation for subsequent machining of high-precision ultrasonic tool holders.

[0037] As a preferred implementation, the heat treatment includes a stepped heating process. Compared to single-stage annealing, which directly heats to the target temperature, the stepped heating system allows for more precise control over the evolution of the microstructure. For example, preheating can be performed at 400–500°C to homogenize the temperature inside and outside the rod and initially release surface stress; subsequently, the temperature is increased at a slower rate to the main heat treatment zone at 550–750°C for a longer period. This stepped temperature control is beneficial for the stable precipitation and growth of the α phase, promoting the formation of crystallographically preferred orientation, thereby achieving high texture strength. After the above low-temperature heat treatment, the microstructure of the titanium alloy rod for ultrasonic scalpels meets the following conditions: average grain size of 2–3 μm; α phase volume fraction ≥96%; texture strength ≥5.0. These microscopic parameters are core indicators for evaluating whether a material possesses excellent ultrasonic transmission performance. Among them, the ultrafine grain size of 2~3μm ensures the high strength and low internal loss of the material; the high α phase ratio of ≥96% utilizes the excellent longitudinal acoustic wave transmission characteristics of the α-Ti hexagonal close-packed structure in the c-axis direction; and the texture strength of ≥5.0 means that the c-axis of most grains is aligned with the height of the rod axis, which greatly reduces the acoustic wave scattering and mode conversion loss at the grain boundaries.

[0038] To quantitatively verify the product characteristics obtained by the above process, a comprehensive microscopic characterization was performed on the Φ6.0mm titanium alloy bar prepared in this embodiment. For example... Figure 4 As shown, the microstructure of the finished bar exhibits fine and uniform grains with no obvious abnormal growth, indicating that the effects of the previous thermomechanical treatment have been well inherited. Figure 5 As shown in the phase distribution diagram of the heat-treated bar stock, the α phase (Ti-Hex) accounts for 96.9% of the volume, while the β phase (Titanium cubic) accounts for only 2.1%, fully meeting the requirement of α phase ≥ 96%. Figure 6 As shown, the inverse pole figure and grain size statistics indicate that the average grain size of the rod is 2.5 μm, falling within the target range of 2~3 μm; the texture intensity shown by the Z1-Ti-Hex inverse pole figure reaches 5.16, significantly higher than the lower threshold of 5.0. These data fully demonstrate that the present invention successfully achieves dual anchoring of PrOduct-by-prOcess through vacuum low-temperature heat treatment combined with anti-deformation tooling and a stepped heating regime, that is, specific process parameters inevitably lead to specific high-performance microstructures.

[0039] To verify the criticality of the above-mentioned process parameter window and its substantial impact on ultrasonic performance, this embodiment also sets up the following two comparative examples for verification.

[0040] Comparative Example C: The same chemical composition and pre-processing technology as Example 4 were used, but anti-deformation fixtures were not used during the heat treatment stage. Instead, the bar was freely placed in a vacuum furnace for heat treatment at 580°C. The results showed that the straightness deviation of the bar after heat treatment exceeded 0.5 mm / m, far exceeding the 0.2 mm / m standard required for ultrasonic tool bar processing, resulting in a large number of scraps. More seriously, due to the lack of external constraints, the bar underwent uncontrollable micro-twisting during stress release, leading to the destruction of the crystallographic texture. The measured texture strength dropped to 3.2, and the manufactured tool bar exhibited an amplitude attenuation rate of 18% in ultrasonic vibration testing, with the average cutting time extended to 10.5 s, indicating significant performance degradation.

[0041] Comparative Example D: Using the same composition, tooling, and stepped heating regime as Example 4, but increasing the main holding temperature to 800°C. Results showed that although the straightness was acceptable, the grains significantly coarsened due to the temperature exceeding the recrystallization critical point, with the average grain size increasing to 5.8 μm. Simultaneously, the β-phase transformation amount increased, and the α-phase volume fraction decreased to 91.5%. Texture strength also decreased to 4.1 due to grain coarsening and phase transformation. The tool holder machined from this comparative example bar exhibited an average cutting time of 9.8 s and a bleeding rate of 4% due to enhanced grain boundary scattering and a reduced effective sound transmission cross-section, failing to meet the clinical requirements for efficient cutting and hemostasis.

[0042] The comparative results above conversely confirm that the "low temperature range of 550~750℃" and "anti-deformation tooling constraint" defined in this invention are not simply a combination of processes, but a necessary technical combination based on the physical metallurgical principles of titanium alloys and the ultrasonic transmission mechanism. Only within this specific window can multiple objectives such as fine grains, high α phase, strong texture, and high straightness be achieved simultaneously, thereby endowing the ultrasonic scalpel holder with superior clinical performance comparable to imported products. It should be understood that although this embodiment provides specific examples of heating steps and comparative data, in actual production, as long as the heat treatment process can meet the above-mentioned microstructure and straightness requirements, the specific tooling material, furnace loading method, and temperature control curve can be adaptively adjusted according to equipment conditions, and all of these fall within the protection scope of this invention. Example

[0043] This embodiment provides an ultrasonic scalpel handle, including a handle body, which is machined from the titanium alloy rod used for ultrasonic scalpels described in Embodiment 4. Specifically, this ultrasonic scalpel handle is a core component of a terminal medical device manufactured by precision machining from the aforementioned titanium alloy rod with specific microstructural characteristics. Figure 7As shown, the rod structure includes a hook-shaped working end, a straight rod body, and a connecting end connected in sequence, with the connecting end having a transversely penetrating mounting hole. In this structure, the hook-shaped working end serves as the execution part that directly contacts biological tissue; its specific hook-shaped design facilitates tissue gripping, separation, and coagulation. The straight rod body acts as a longitudinal waveguide for ultrasonic energy transmission; its geometric precision and the uniformity of the internal material structure jointly determine the efficiency and stability of energy transmission. The connecting end achieves rigid mechanical coupling with the ultrasonic handle through the transversely penetrating mounting hole, ensuring that high-frequency vibration energy can be transferred from the transducer to the rod body without loss. It should be understood that although... Figure 7 A specific hook-shaped working end is shown, but in other embodiments, depending on the surgical scenario, the working end can also be processed into a ball-shaped, scissor-shaped, or other shapes suitable for specific surgical procedures, as long as its base material originates from the titanium alloy rod obtained by the specific preparation method described in this invention, all of which fall within the protection scope of this invention. The core of this embodiment is that the excellent acoustic response characteristics of the scalpel rod do not only depend on the design of the macroscopic geometry, but more fundamentally stem from the microstructure of the rod obtained in Example 4, which has an average grain size of 2~3μm, an α phase volume ratio of ≥96%, and a texture strength of ≥5.0. This structure greatly reduces grain boundary scattering and internal friction of ultrasound during transmission.

[0044] Based on this, this embodiment also provides an ultrasonic scalpel system, including an ultrasonic main unit, a handle, and the aforementioned ultrasonic scalpel shaft. In this system, the ultrasonic main unit is electrically connected to the handle, and the handle is mechanically connected to the ultrasonic scalpel shaft; the ultrasonic main unit is configured to transmit ultrasonic energy to the ultrasonic scalpel shaft through the handle. Specifically, the ultrasonic main unit generates a high-frequency electrical signal at a specific frequency (typically around 55.5 kHz), which drives a piezoelectric ceramic transducer in the handle to convert it into longitudinal mechanical vibration of the same frequency; this mechanical vibration is then transmitted to the scalpel shaft via the connecting end and along the straight shaft to the hook-shaped working end, causing the working end to perform high-frequency reciprocating motion with an amplitude of tens of micrometers, thereby achieving the cutting of biological tissue and protein coagulation hemostasis. Because the titanium alloy bar used in this invention has undergone a series of coordinated process controls, including narrow-range composition control, multi-fire upsetting and reversing forging, large deformation hot continuous rolling, and vacuum low-temperature anti-deformation heat treatment, it has formed a highly preferred orientation strong texture and ultra-fine equiaxed crystal structure inside. This makes the transmission loss of ultrasonic energy inside the tool holder significantly lower than that of conventional TC4ELI materials, thereby ensuring that the system can obtain a higher tool head amplitude and a more stable resonant frequency under the same input power.

[0045] To verify the actual clinical performance of the ultrasonic scalpel handle and system provided by this invention, the handle prepared in this embodiment was assembled into a standard ultrasonic scalpel system for animal tissue cutting and hemostasis experiments, and compared with existing domestically produced similar handles and imported benchmark products. The experimental results showed that the system using the handle of this invention had an average cutting time of approximately 7.6 seconds in 100 cutting tests (specific test samples were 7.75 seconds, 7.58 seconds, and 7.68 seconds), with a bleeding rate controlled below 2% (only 1-2 cases of slight bleeding in 100 cases). In contrast, the handle made from existing domestically produced ordinary TC4ELI rod material had an average cutting time as long as 12.82 seconds and a bleeding rate as high as 6%, showing a significant performance difference. Furthermore, the performance indicators of the handle of this invention are comparable to those of imported benchmark products (average cutting time 7.84 seconds, bleeding rate 1%), and even slightly better in some test groups. This unexpected technical effect fully demonstrates that the present invention, through the targeted control of the microstructure of titanium alloy materials, has successfully solved the long-standing bottleneck problems of low energy transmission efficiency, slow cutting, and poor hemostasis in domestically produced ultrasonic scalpel shafts. The essential reason for this performance improvement lies in the high-velocity, low-damping microstructure characteristics within the material, rather than simply optimizing its geometric shape. This establishes the substantial technical advantage and commercial value of the present invention in the field of high-end medical ultrasonic scalpel materials.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the chemical composition ratio, melting and forging process parameters, heat treatment regime, and specific microstructure obtained therefrom of the titanium alloy rods for ultrasonic scalpels in the above embodiments are preferred examples listed to achieve the inventive objective of improving ultrasonic energy transmission efficiency, and are not exhaustive limitations of the present invention. Any adjustments to the order of the above process steps, equivalent substitutions of parameters, adaptive changes to the tooling structure, or other changes and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical concept of the present invention, without departing from the core principles of the present invention, should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a titanium alloy rod for an ultrasonic scalpel, characterized in that, Includes the following steps: Smelting: Raw materials containing titanium, aluminum and vanadium are mixed and pressed into electrodes, and then vacuum smelted to obtain an ingot; the chemical composition of the ingot, by weight percentage, includes: Al: 6.10~6.60%, V: 3.60~4.10%, O: 0.08~0.14%, Fe≤0.10%, with the balance being Ti and unavoidable impurities; Forging: The ingot is forged, and at least two upsetting and drawing reversal processes are performed to obtain a square billet; Rolling: The billet is hot-rolled to obtain coiled wire. Heat treatment: The rod obtained based on the coiled wire is subjected to low-temperature heat treatment in a vacuum environment to obtain the titanium alloy rod for ultrasonic scalpel.

2. The method for preparing titanium alloy rods for ultrasonic scalpels according to claim 1, characterized in that, The chemical composition of the ingot, by weight percentage, includes: Al: 6.20~6.50%, V: 3.70~4.0%, O: 0.10~0.13%, Fe<0.1%, N<0.05%, C<0.05%, and the content of other impurities is less than 0.1%. The pressed electrode comprises: continuously and integrally pressing the raw material using a hydraulic press to obtain the electrode with a density of 3.8~4.2 g / cm³.

3. The method for preparing titanium alloy rods for ultrasonic scalpels according to claim 2, characterized in that, The vacuum melting process includes performing three vacuum melting processes, with the diameter of the resulting ingots increasing sequentially. The diameter of the ingot obtained from the first smelting is 550~600mm, the diameter of the ingot obtained from the second smelting is 620~660mm, and the diameter of the ingot obtained from the third smelting is 700~750mm.

4. The method for preparing titanium alloy rods for ultrasonic scalpels according to claim 1, characterized in that, The forging is a multi-fire upsetting and drawing reversing forging, which includes: Forging of blanks: carried out at a heating temperature of 1100~1150℃; Intermediate upsetting and reversing forging: At least two upsetting and reversing operations are performed at a heating temperature of 950~1100℃; Final forging: Forging into the square billet with a cross-sectional size of 140×140mm to 160×160mm.

5. The method for preparing titanium alloy rods for ultrasonic scalpels according to claim 4, characterized in that, The intermediate upsetting and reversing forging process includes a first heating cycle, a second heating cycle, and a third heating cycle performed sequentially, with the heating temperature decreasing sequentially. The hot continuous rolling process includes rolling at a heating temperature of 930~960℃, and supplementing the temperature during the rolling process to ensure that the final rolling temperature is not lower than 850℃, followed by rapid water cooling after rolling.

6. The method for preparing titanium alloy rods for ultrasonic scalpels according to claim 1, characterized in that, The low-temperature heat treatment includes: The bar is subjected to heat treatment at a temperature of 550~750°C in a vacuum heat treatment furnace with a vacuum degree of 10⁻³Pa or higher. During the heat preservation process, the bars are tightly arranged within the anti-deformation fixture to limit the deformation of the bars.

7. The method for preparing titanium alloy rods for ultrasonic scalpels according to claim 6, characterized in that, The heat preservation treatment includes setting up a heating step for heat preservation; After the aforementioned low-temperature heat treatment, the microstructure of the titanium alloy rod for the ultrasonic scalpel meets the following conditions: The average grain size is 2~3μm; The volume percentage of the α phase is ≥96%; Texture strength ≥ 5.

0.

8. A titanium alloy rod for ultrasonic scalpels, characterized in that, The titanium alloy rod for ultrasonic scalpel is prepared by any one of claims 1 to 7. The microstructure of the titanium alloy rod for the ultrasonic scalpel meets the following requirements: average grain size of 2~3μm, volume fraction of α phase ≥96%, and texture strength ≥5.

0.

9. An ultrasonic surgical scalpel handle, characterized in that, Includes a rod body, which is machined from the titanium alloy rod material for ultrasonic scalpels as described in claim 8; The rod body includes a hook-shaped working end, a straight rod body, and a connecting end connected in sequence, and the connecting end is provided with a horizontal through mounting hole.

10. An ultrasonic surgical scalpel system, characterized in that, Includes an ultrasonic main unit, a handle, and the ultrasonic surgical scalpel as described in claim 9; The ultrasound host is electrically connected to the handle, and the handle is mechanically connected to the ultrasound scalpel handle; the ultrasound host is configured to transmit ultrasound energy to the ultrasound scalpel handle through the handle.

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