Ultrasonic transducer capable of realizing high torsional vibration-longitudinal vibration amplitude ratio and design method thereof

Abstract

The invention relates to an ultrasonic transducer capable of realizing a high torsional vibration-longitudinal vibration amplitude ratio and a design method thereof. The ultrasonic transducer comprises a piezoelectric ceramic vibrator 3, an amplitude-change pole 2 and a tool head 1 which are connected in sequence, the shape of the amplitude-change pole is formed by rotating a specific geometric curve around the axis. The interior of the amplitude-change pole is of a cavity structure 5, the wall thickness distribution of the amplitude-change pole is adjustable, the cavity structure is a through hole or a blind hole, and the shape of the cavity structure is an equal-diameter cavity extending along the axis or a special-shaped cavity formed by rotating a specific geometric curve around the axis. By optimizing the internal cavity structure and the wall thickness distribution and adjusting the amplitude proportion between torsional vibration and longitudinal vibration, the longitudinal vibration of the transducer can be converted into longitudinal torsional vibration, so that the transducer has both longitudinal vibration and torsional vibration. Due to the unique cavity type structure in the amplitude-change pole, the amplitude ratio of generated torsional vibration to longitudinal vibration can be larger, the ultrasonic effect with the high torsional vibration-longitudinal vibration amplitude ratio can be generated, and vibration output with the high torsional vibration-longitudinal vibration amplitude ratio can be achieved.

Description

Technical Field

[0001] The present invention relates to an ultrasonic transducer and its design method for achieving a high torsional-vibrational amplitude ratio through internal cavity and wall thickness optimization. The ultrasonic transducer is used for ultrasonic machining, which can efficiently amplify the weak vibration generated by the transducer, realize the conversion of vibration modes, and generate ultrasonic vibrational mechanical energy with a high torsional-vibrational amplitude ratio, thereby improving the machining efficiency and quality. Background Art

[0002] Silicon carbide fiber-reinforced ceramic matrix composite (SiC f / SiC) has become an important new type of thermal structure material due to its excellent properties such as high strength, high temperature resistance, and corrosion resistance, and has been gradually widely used in the aerospace field. However, in the traditional machining process, due to the high strength and high hardness characteristics of the material, it faces serious tool wear and poor machining surface quality problems, which limit the further application of SiC f / SiC composites.

[0003] As an advanced machining method, ultrasonic vibration-assisted machining significantly reduces the machining force, improves the machining efficiency, enhances the surface quality, and extends the tool life by introducing an ultrasonic vibration device in traditional machining. Especially when machining complex hole structures, the ultrasonic vibration-assisted machining method with a high torsional-vibrational amplitude ratio can significantly improve the machining efficiency and surface quality, thus providing an effective solution for the high-precision machining of SiC f / SiC composites.

[0004] From the currently published information on ultrasonic transducers, the horn is always a solid horn. Its structure has certain limitations in improving the torsional-vibrational amplitude ratio, and the generated torsional-vibrational amplitude ratio is relatively small, making it difficult to meet the requirements of some complex shape machining and high-precision machining. Therefore, it is necessary to design a horn of an ultrasonic transducer with a high torsional-vibrational amplitude ratio to improve the machining accuracy and efficiency.

[0005] For example, the invention patent application with the publication number CN115069523A discloses a longitudinal-torsional composite ultrasonic vibration-assisted milling machining device, which includes a non-contact power transmission unit and a longitudinal-torsional composite ultrasonic transducer unit. This patent obtains different waveguides by changing the helix angle of the helical groove, the number of helical grooves, and the diameters of the large and small end faces of the frustum section, so as to obtain different longitudinal-torsional conversion ratios. However, this scheme adjusts the longitudinal-torsional conversion ratio by adjusting the waveguide parameters (helix angle, number of grooves, and frustum diameter), and its transducer body is still a rigid solid structure, which is quite different from the scheme of the present invention that changes the torsional stiffness by changing the horn structure to adjust the torsional-vibrational amplitude ratio, and it cannot give an improvement inspiration.

[0006] The invention patent application with the publication number CN202411487514.4 discloses a sandwich-type longitudinal-torsional composite vibration power ultrasonic welding transducer and method. Through the sandwich-type structure design, this patent integrates a torsional vibration component and a longitudinal vibration component and connects them to a power supply system with the same frequency. This patent generates torsional vibration and longitudinal vibration independently through the two components respectively, and realizes efficient mode superposition inside the transducer to form a longitudinal-torsional composite vibration output. However, this patent adjusts the longitudinal-torsional conversion ratio through the mode superposition of the two components, and the torsional stiffness of the horn remains unchanged. Its technical route is different from the solution of the present invention, which changes the torsional stiffness by structurally adjusting the horn to adjust the amplitude ratio of torsional vibration to longitudinal vibration, and it cannot give an improvement inspiration.

[0007] The invention patent application with the publication number CN202420113094.2 discloses a composite vibration ultrasonic tool shank. The ultrasonic transducer assembly includes two or more stacked piezoelectric ceramic sheets and electrode sheets that provide an electric field for the piezoelectric ceramic sheets. The piezoelectric ceramic sheets include one or more polarized piezoelectric ceramic units. In each piezoelectric ceramic sheet, the polarization directions of the piezoelectric ceramic units corresponding to each other are not completely the same. After applying an electric field, the ultrasonic transducer assembly can drive the horn and enable the ultrasonic tool shank to achieve composite vibration. However, this solution mainly relies on the stacked configuration of anisotropically polarized piezoelectric ceramic units to achieve composite vibration excitation. Its transducer assembly uses a fixed solid structure, which is different from the core idea of the present invention to adjust the amplitude ratio of torsional vibration to longitudinal vibration through the optimization of the internal cavity and wall thickness. There are significant differences in the technical implementation path and adjustment means, and it cannot give an improvement inspiration.

[0008] The invention patent application with the publication number CN201910944140.7 discloses a design method for a longitudinal-torsional composite vibration ultrasonic horn based on frequency coupling. This patent obtains the preset vibration frequency and multiple preset dimension information of the ultrasonic horn, and assigns a preset value range to the to-be-preset dimension information; and based on the preset vibration frequency and multiple preset dimension information, obtains the frequency difference between the first resonance frequency and the second resonance frequency corresponding to each value within the preset value range of the to-be-preset dimension information, and determines the minimum frequency difference; finally, takes the value of the to-be-preset dimension information corresponding to the minimum frequency difference as the target preset value of the to-be-preset dimension information, and the target preset value is used to indicate that the first resonance frequency and the second resonance frequency reach coupling, so that the ultrasonic horn can excite the maximum torsional vibration amplitude output value. Although this technical solution improves the torsional vibration output efficiency through the frequency coupling mechanism, the horn body still adopts a conventional solid structure design and does not structurally adjust the torsional stiffness of the horn. It has an essential difference from the core innovation point of the present invention to change the torsional stiffness through the optimization of the cavity and wall thickness to increase the torsional-longitudinal ratio, and it cannot give an improvement inspiration. Summary of the Invention

[0009] Objective of the Invention: In the existing ultrasonic transducer technology, the limitation in regulating the torsional-vibrational amplitude ratio makes it difficult to meet the high-efficiency and high-precision processing standards when dealing with the complex physical properties and specific processing requirements of SiC f / SiC composite materials, and it cannot satisfy the growing high-quality demand for the processing of SiC f / SiC composite materials in modern industry. The present invention provides an ultrasonic transducer capable of achieving a high torsional-vibrational amplitude ratio and its design method. By optimizing the structural design of the horn to change the torsional stiffness, the torsional-vibrational amplitude ratio can be adjusted, and ultrasonic vibrations with a high torsional-vibrational amplitude ratio can be generated, which is particularly suitable for the processing of complex structures such as deep holes, shaped holes, and thin-walled structures. This design can significantly improve the processing efficiency and surface quality, and optimize the energy conversion and transmission process.

[0010] Technical Solution: To achieve the above objective of the invention, the present invention provides an ultrasonic transducer capable of achieving a high torsional-vibrational amplitude ratio and its design method.

[0011] An ultrasonic transducer capable of achieving a high torsional-vibrational amplitude ratio includes: a piezoelectric ceramic oscillator, a horn, and a tool head, which are connected in sequence; the interior of the ultrasonic horn is a cavity structure, and a spiral groove is provided on the outer periphery. By optimizing the internal cavity geometric structure and wall thickness distribution, the torsional stiffness characteristics of the structure are changed. This design can effectively adjust the amplitude ratio between torsional vibration and longitudinal vibration. Furthermore, ultrasonic vibrations with a high torsional-vibrational amplitude ratio can be generated, converting the longitudinal vibration of the transducer into longitudinal-torsional vibration, making the transducer have both longitudinal vibration and torsional vibration. And due to the unique cavity structure inside the horn, the amplitude ratio of the generated torsional vibration to the longitudinal vibration can be made larger, enabling it to produce an ultrasonic effect with a high torsional-vibrational amplitude ratio.

[0012] Specifically, the interior of the horn is designed with an equal-diameter or shaped cavity structure, which can not only change the torsional stiffness but also optimize the transmission efficiency of vibration energy. At the same time, a spiral groove structure is designed on the outer side of the horn. By changing the number, depth, width, and pitch of the grooves, the vibration mode of the transducer is further optimized. Through the collaborative design of the internal cavity structure and the external spiral groove structure, the present invention can achieve the vibration characteristics of a high torsional-vibrational amplitude ratio.

[0013] The outer surface curve of the ultrasonic horn (transition section) is formed by rotating a specific geometric curve around the axis; the cavity structure includes two implementation forms of through holes and blind holes, and its shape includes a constant-diameter cavity structure extending along the axis or a special-shaped cavity structure formed by rotating a specific geometric curve around the axis; the wall thickness of the horn can be adjusted by the distance difference between the outer shape geometric curve and the cavity geometric curve from the axis. The spiral grooves are evenly distributed around the horn for n (for example, n = 4 - 8) turns, and the spiral angle is θ (for example, θ = 45° ± 5°).

[0014] The design method of the ultrasonic transducer with a high torsional vibration - longitudinal vibration amplitude ratio involved in the present invention includes the following steps:

[0015] Step 1: According to the target frequency f0, select relevant components of the piezoelectric ceramic oscillator. For the horn and the front and rear covers, comprehensively consider various factors such as the acoustic properties, mechanical properties, and stability of the material, and select a metal material that meets the requirements of longitudinal - torsional composite vibration; for the piezoelectric ceramic sheet, combined with the target frequency f0 and the overall performance requirements of the transducer, reasonably select the structural size parameters of the piezoelectric ceramic sheet.

[0016] Step 2: Based on the half - wavelength resonance theory or full - wavelength resonance theory of the sandwich - type piezoelectric transducer, combined with the design parameters of the target frequency f0 and amplitude A, establish a basic structure model of the transducer through the sound velocity characteristic equation.

[0017] Step 3: Design and select the outer shape curve of the ultrasonic horn with a high torsional vibration - longitudinal vibration amplitude ratio. The ultrasonic horn is formed by rotating a logarithmic, exponential, or other specific geometric curve around the axis, so that the ultrasonic horn has a high energy transfer efficiency.

[0018] Step 4: Design the spiral groove structure so that the longitudinal vibration part transmitted by the ultrasonic vibration transducer is converted into torsional vibration, so as to obtain both longitudinal vibration components and torsional vibration components at the end of the ultrasonic horn.

[0019] Step 5: Design and adjust the cavity structure and wall thickness of the ultrasonic horn. Select a suitable cavity type and cross - section shape according to the usage scenario requirements of the ultrasonic tool shank. On this basis, optimize the wall thickness gradient so that the horn has good torsional stiffness characteristics, and then effectively optimize the torsional vibration - longitudinal vibration amplitude ratio characteristics of the ultrasonic tool shank to achieve ultrasonic vibration with a high torsional vibration - longitudinal vibration amplitude ratio.

[0020] Step 6: Based on the structural modal analysis of three - dimensional modeling and finite - element simulation, use three - dimensional modeling software to construct the structural model of the ultrasonic transducer. After completing the modeling, with the help of finite - element simulation technology, conduct structural modal analysis on the model to obtain key parameters such as the resonance frequency, amplitude distribution, node position, and torsional - longitudinal amplitude ratio of the horn.

[0021] Step 7: Based on the simulation data in Step 6, for the modal results that deviate from the design objectives, optimize the structural dimensions, material layout, or constraint conditions until the preset vibration frequency and vibration mode distribution requirements are met, such as Figure 8 shown.

[0022] Beneficial effects:

[0023] The ultrasonic horn for achieving a high torsional vibration - longitudinal vibration amplitude ratio through internal cavity and wall thickness optimization according to the present invention has a unique structural design. Through the collaborative design of the cavity structure and the spiral groove structure, the present invention can make the amplitude ratio of the torsional vibration and the longitudinal vibration generated by the ultrasonic tool handle larger, enabling it to produce an ultrasonic effect with a high torsional vibration - longitudinal vibration amplitude ratio. Therefore, it has excellent vibration characteristics, can effectively improve the processing efficiency and accuracy, and has unique advantages in the processing of cutting, drilling, grinding, etc. of metal and non - metal materials. In addition, the design method involved in the present invention has good processability, is simple to manufacture, and has low cost.

[0024] The ultrasonic horn with the high torsional vibration - longitudinal vibration amplitude ratio can be adaptively adjusted according to different processing technologies and material characteristics, and has a wide range of applications. It can be used for the processing of materials such as superalloys and ceramic substrates in the aerospace field, the precision processing of metal parts in automobile manufacturing, and the processing of complex shapes in mold manufacturing, etc.

[0025] With its good energy conversion and transmission performance, for difficult - to - machine materials such as SiC f / SiC ceramic matrix composites, this structure can effectively reduce the cutting force and cutting heat, improve the cutting performance of the material, reduce tool wear and breakage, improve the processing efficiency and quality, and achieve high - efficiency and high - precision processing of complex structures. It conforms to the development trend of energy - efficient and energy - saving processing. Description of the Drawings

[0026] Figure 1 is the structural diagram of the ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to the present invention;

[0027] Figure 2 is the structural schematic diagram of the piezoelectric ceramic oscillator 3;

[0028] Figure 3 is the structural schematic diagram of the horn of one embodiment of the present invention (the cavity structure 5 is an equal - diameter blind - hole - type cavity): (a) stereogram, (b) cross - sectional view;

[0029] Figure 4 is the structural schematic diagram of the spiral groove 6: (a) front view, (b) top view of the cross - sectional structure.

[0030] Figure 5Schematic diagram of the horn in the second embodiment of the present invention (the cavity structure 5 is an equal-diameter through-hole cavity): (a) Stereogram, (b) Cross-sectional view;

[0031] Figure 6 Schematic diagram of the horn in the third embodiment of the present invention (the cavity structure 5 is an equal-wall-thickness blind-hole cavity): (a) Stereogram, (b) Cross-sectional view;

[0032] Figure 7 Schematic diagram of the horn of the ultrasonic transducer in the fourth embodiment of the present invention (the cavity structure 5 is an equal-wall-thickness blind-hole cavity): (a) Stereogram, (b) Cross-sectional view;

[0033] Names of each label in the figure: tool head - 1, horn - 2, piezoelectric ceramic oscillator - 3, horn body - 4, cavity structure - 5, spiral groove - 6, front cover plate 7, rear cover plate 8, piezoelectric ceramic sheet 9.

[0034] Figure 8 Modal optimization flowchart of the ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to the present invention;

[0035] Figure 9 Overall structure model diagram of the ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to the present invention;

[0036] Figure 10 Mesh division result diagram of the ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to the present invention;

[0037] Figure 11 Modal simulation result diagram of the ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to the present invention. Detailed implementation manners

[0038] In order to enable those skilled in the art to better understand the technical solutions in this patent application of the present invention, the technical solutions in this application will be clearly and completely described below with reference to the accompanying drawings in this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts should fall within the scope of protection of this application.

[0039] Please refer to Figures 1 to 2An ultrasonic transducer with a high torsional vibration - longitudinal vibration amplitude ratio includes: a piezoelectric ceramic oscillator, a horn, and a tool head, which are connected in sequence; a spiral groove structure with different helix angles, groove lengths, and groove widths is provided on its outer periphery to change the vibration mode of the transducer, and a cavity structure with different shapes and wall thicknesses is provided inside the ultrasonic horn to change the structural characteristics and thus change the torsional stiffness of the transducer; the longitudinal - torsional ratio of the transducer is adjusted through the structural design of the outer - peripheral spiral groove structure and the inner cavity to achieve the vibration characteristics of a high torsional vibration - longitudinal vibration amplitude ratio.

[0040] The axis of the cavity structure 5 coincides completely with the axis of the ultrasonic horn 2. The cavity structure 5 includes two implementation forms: through - holes and blind holes, and its shape includes a constant - diameter cavity structure extending along the axis or a special - shaped cavity structure formed by rotating a specific geometric curve around the axis.

[0041] The spiral grooves 6 are evenly distributed around the outer periphery of the horn, with a total of n, and the helix angle is θ.

[0042] The design method steps of an ultrasonic transducer with a high torsional vibration - longitudinal vibration amplitude ratio are as follows:

[0043] Step 1: Select relevant components of the ultrasonic transducer according to the target frequency f0.

[0044] (1) The ultrasonic transducer mentioned above includes front and rear covers and a piezoelectric ceramic sheet fixed by clamping with the front and rear covers. The horn is connected to the front cover of the piezoelectric transducer. For the horn and the front and rear covers, comprehensively consider various factors such as the acoustic performance, mechanical performance, and stability of the material, and select a metal material that meets the requirements of longitudinal - torsional composite vibration.

[0045] (2) For the piezoelectric ceramic sheet, reasonably select the structural size parameters of the piezoelectric ceramic sheet in combination with the target frequency f0 and the overall performance requirements of the transducer.

[0046] Step 2: Based on the half - wavelength resonance theory or full - wavelength resonance theory of the sandwich - type piezoelectric transducer, design the dimensions of each part of the basic structure model of the transducer. The specific process includes:

[0047] (1) Calculation of the working wavelength: Calculate the working wavelength λ according to the wave equation λ = c / f0, where c represents the equivalent sound speed in the material.

[0048] (2) Definition of the axial reference dimension: Determine the total length parameter l 总 = λ / 2 or l 总 = λ, and establish the axial reference dimension of the wavelength resonator.

[0049] (3) Vibration node optimization and dimension allocation: Based on the vibration node theory, the flange assembly surface is accurately set on the displacement node plane, and the axial dimensions of the front cover plate (radiation end), rear cover plate (drive end), and horn are reasonably allocated through finite element modal (Ansys) analysis; the length l of the horn is obtained. 变 .

[0050] Step 3: Parametric optimal design of the horn outer shape curve based on acoustic impedance matching. Its specific process includes:

[0051] (1) Design and selection of the outer shape curve of the ultrasonic horn with a high torsional vibration - longitudinal vibration amplitude ratio. The ultrasonic horn is formed by rotating a logarithmic type r(z) = r0e kz , exponential type r(z) = r0 + az b or other specific geometric curves around the axis.

[0052] (2) Compare the acoustic impedance matching characteristics of different configurations through finite element harmonic response analysis, and screen the geometric parameter combination with the optimal energy loss rate.

[0053] Step 4: Optimize the design of the spiral groove structure based on waveguide parameter adjustment, and implement parametric structure design: Determine the groove width characteristic ratio, groove length ratio, spiral angle optimization range, and the number of spiral grooves of the spiral groove.

[0054] Step 5: Collaborative optimization design of the cavity structure based on anti - torsional stiffness gradient regulation. Its specific implementation includes:

[0055] (1) Cavity type selection: Select a suitable cavity type according to the scenario requirements. The through - hole type cavity is suitable for high - power long - time working scenarios (heat dissipation requirements are prioritized), and its penetration length L 通孔 = L 变 (working length of the horn), as shown in Figure 5 , Figure 7 ; The blind - hole type cavity is suitable for high - stiffness requirement scenarios, and the blind - hole depth h satisfies 0.4L 变 ≤ h ≤ 0.9L 变 . As shown in Figure 3 , Figure 6 .

[0056] (2) Cavity cross - section shape design: The equal - diameter cavity is used for linear stiffness adjustment, and the diameter d satisfies 0.2D ≤ d ≤ 0.8D (D is the outer diameter of the horn), as shown in Figure 3 , Figure 5 ; The variable - cross - section cavity is used for non - linear stiffness adjustment, and is generated by rotating a logarithmic curve r(z) = r0e kz or an exponential curve r(z) = r0 + az b around the axis (r0 is the initial radius, k, a, b are shape coefficients). As shown in Figure 6 ,Figure 7 as shown

[0057] (2) Perform gradient wall thickness optimization: First, perform theoretical modeling on the wall thickness. Based on the torsional stiffness formula of thin-walled tubes K = 2πGt(z) 3 / 3, establish the gradient distribution function of the wall thickness t(z) along the axial direction z: Linear gradient: t(z) = t max -(t max -t min )z / L 变 ; Nonlinear gradient: t(z) = t min +Δt·sin2(πz / 2L 变 ). Then optimize under the constraint conditions of the minimum wall thickness t min ≥c (c is the safety threshold of the yield strength of the material used); the wall thickness change rate |dt / dz| ≤ 0.3 mm / mm

[0058] (3) Simulation verification and optimization: Based on ANSYS Workbench, establish a parametric model, compare the modal characteristics under different cavity-wall thickness combinations, and maximize the torsional-longitudinal amplitude ratio

[0059] Step 6: Structural modal analysis based on 3D modeling and finite element simulation. The specific operation process includes

[0060] (1) Use SolidWorks 3D modeling software to establish a geometric model and export it as an STP format file

[0061] (2) Create a Modal analysis module in the ANSYS Workbench platform, import it into the project analysis area, and construct a complete modal simulation process

[0062] (3) Import the STP format 3D model file generated in (1) through the Geometry module of the Modal analysis project, as Figure 9 shown

[0063] (4) Double-click the Engineering Data module to create piezoelectric ceramic and metal material databases respectively, and define key parameters such as elastic modulus, piezoelectric constant, dielectric coefficient, density, and Poisson's ratio of the materials

[0064] (5) Right-click on the Mesh module and execute the Generate Mesh command. Automatically discretize the geometric domain using high-order tetrahedral elements (SOLID187), and use Sizing for size control, as Figure 10 shown

[0065] (6) Set the maximum modal order (e.g., 20 orders) and the target frequency range (e.g., 15 kHz - 20 kHz) in the Analysis Settings, and select the Block Lanczos algorithm for modal extraction to ensure a balance between computational efficiency and accuracy.

[0066] (7) Right-click to activate the Solve command of the Solution module, start the solver to execute the calculation task, and monitor it in real time through Solution Information.

[0067] (8) In the post-processing stage, extract the natural frequencies and mode shape contour maps of each order of mode, and combine with the Animate function to perform mode shape animation demonstration to verify the vibration energy distribution characteristics, and obtain key parameters such as the resonance frequency, amplitude distribution, node position, and longitudinal-torsional amplitude ratio of the horn. As Figure 11 shown.

[0068] Step 7: Based on the simulation data in Step 5, for the modal results that deviate from the design target, iteratively optimize the structural dimensions, material layout, or constraint conditions until the preset vibration frequency and mode shape distribution requirements are met.

[0069] (1) Judge whether the vibration frequency meets the requirements. If the frequency obtained through modal simulation is greater than the target frequency, consider trying to increase the sizes of the front cover plate and the rear cover plate. Conversely, decrease them.

[0070] (2) Judge the mode shape distribution and check whether the nodes are located at the flange. If the node position is biased towards the front cover plate direction, consider trying to decrease the length of the front cover plate or increase the length of the rear cover plate; similarly, if the node position is biased towards the rear cover plate direction, try to decrease the length of the rear cover plate or increase the length of the front cover plate.

[0071] (3) Comprehensively consider the vibration frequency and mode shape distribution, adjust the structural dimensions of the transducer, and perform modal simulation again to verify whether the requirements are met.

[0072] (4) If adjusting the lengths of the front and rear cover plates still cannot make the frequency and mode shape meet the requirements, consider making further adjustments to the structure such as changing the material layout or the size of the piezoelectric ceramic chips, and repeat the previous steps until the preset vibration frequency and mode shape distribution requirements are met.

[0073] The technical solution of the present invention will be specifically described below in combination with the embodiments and the accompanying drawings.

[0074] Embodiment 1

[0075] Taking a longitudinal-torsional ultrasonic tool shank for ultrasonic machining with a target frequency f0 = 29 KHz and an amplitude A = 3 μm as an example for design, the specific design process includes:

[0076] Step 1: Select relevant components of the piezoelectric transducer according to the target frequency f0 = 29 KHz.

[0077] (1) For the horn and the front and rear covers, considering various factors such as the acoustic performance, mechanical performance, and stability of the material, the materials of the horn and the front and rear covers are selected as titanium alloy (TC4).

[0078] (2) For the piezoelectric ceramic plates, combined with the target frequency f0 = 29 KHz and the overall performance requirements of the transducer, 4 PZT-8 piezoelectric ceramic plates are selected, and the size is selected as Φ30×Φ10×6.

[0079] Step 2: Based on the wavelength resonance theory of the sandwich piezoelectric transducer, preliminarily design the dimensions of each part of the basic structure model of the transducer. The specific process includes:

[0080] (1) Calculate the working wavelength λ according to the wave equation λ = c / f0, where c represents the equivalent sound speed in the material. The material is titanium alloy (TC4), so λ = 5000 / 29000 ≈ 185 mm;

[0081] (2) Determine the total length parameter l of the transducer 总 = λ = 185 mm, and establish the axial reference dimension of the full-wavelength resonator;

[0082] (3) Based on the vibration node theory, set the flange assembly surface on the displacement node plane, and reasonably distribute the axial dimensions of the front cover (radiating end), rear cover (driving end), and horn through finite element modal analysis; obtain the length l of the horn 1 变 = 30 mm; the small end diameter is 20 mm; the large end diameter is 30 mm; the length of the front cover is 40 mm, the length of the flange is 8 mm, the length of the rear cover is 15 mm, and the remaining length is the length of the tool and nut, see Figure 1 .

[0083] Step 3: Based on the optimal design of the horn outer shape curve for acoustic impedance matching, combined with the selected piezoelectric ceramic plate size Φ30×Φ10×6, design and select the outer shape curve of the ultrasonic horn with a high torsional vibration - longitudinal vibration amplitude ratio. Here, the ultrasonic horn is selected to be formed by rotating a part of a circle.

[0084] Step 4: Design and select the spiral groove structure 1-2, and its structural parameters are:

[0085] (1) Groove width characteristic ratio: w / d min = 1:5

[0086] (2) Groove length ratio: L groove / L horn = 2:3

[0087] (3) Helix angle optimization range: θ = 45°

[0088] (4) Number of helical grooves: n = 6.

[0089] Step 5: Collaborative optimization design of the cavity structure, and its specific process includes:

[0090] (1) Cavity type selection: Select a suitable cavity type according to the scenario requirements. According to the processing requirements for ultrasonic machining, the structure needs to have strong stiffness, so a blind-hole type cavity is selected with a blind-hole depth h = 0.9L 变 , see Figure 3 .

[0091] (2) Cavity cross-section shape analysis: A cavity with equal diameter is used for linear stiffness adjustment, and the diameter d satisfies d = 0.6D (D is the outer diameter of the horn).

[0092] (3) Verify the minimum wall thickness to ensure that the minimum wall thickness is greater than 1 mm.

[0093] Step 6: Structural modal analysis based on 3D modeling and finite element simulation, and the specific operation process includes:

[0094] (1) Use SolidWorks 3D modeling software to establish a geometric model and export it as an STP format file.

[0095] (2) Create a Modal analysis module in the ANSYS Workbench platform and import it into the project analysis area to construct a complete modal simulation process.

[0096] (3) Import the STP format 3D model file generated in (1) through the Geometry module of the Modal analysis project, as Figure 8 shown.

[0097] (4) Double-click the Engineering Data module to create piezoelectric ceramic and metal material databases respectively, and define key parameters such as elastic modulus, piezoelectric constant, dielectric coefficient, density, and Poisson's ratio of the materials.

[0098] (5) Right-click on the Mesh module and execute the Generate Mesh command. Automatically discretize the geometric domain using high-order tetrahedral elements (SOLID187) and use Sizing for size control, as Figure 9 shown.

[0099] (6) Set the maximum modal order (such as 20 orders) and the target frequency domain range (such as: 15 kHz - 40 kHz) in the Analysis Settings, and select the Block Lanczos algorithm for modal extraction to ensure a balance between calculation efficiency and accuracy.

[0100] (7) Right-click to activate the Solve command of the Solution module, start the solver to execute the calculation task, and monitor it in real time through Solution Information.

[0101] (8) In the post-processing stage, extract the natural frequencies and vibration mode nephograms of each order, combine with the Animate function to conduct vibration mode animation demonstrations, verify the vibration energy distribution characteristics, and obtain key parameters such as the resonant frequency, amplitude distribution, node position, and torsional-longitudinal amplitude ratio of the horn.

[0102] Step 7: Based on the simulation data in Step 6, for the modal results deviating from the design target, iteratively optimize the structural dimensions, material layout, or constraint conditions until the preset vibration frequency and vibration mode distribution requirements are met.

[0103] (1) Judge whether the vibration frequency meets the requirements: It is found that the frequency is less than 29KHz; it is necessary to reduce the sizes of the front cover plate and the rear cover plate;

[0104] (2) Judge the vibration mode distribution and check whether the nodes are located at the flange. It is found that the node position is biased towards the rear cover plate direction.

[0105] (3) Considering the vibration frequency and vibration mode distribution comprehensively, adjust the structural dimensions of the transducer, try to reduce the length of the rear cover plate, and conduct modal simulation again to ensure that the resonant frequency offset Δf ≤ ±1.2%f0, as Figure 10 .

[0106] As can be seen from the technical solutions provided by the present invention above, the present invention has the following beneficial effects:

[0107] The present invention optimizes the wall thickness by arranging a cavity structure inside the ultrasonic horn and a spiral groove structure on the outer periphery, and precisely excites ultrasonic vibrations with a high torsional-longitudinal vibration amplitude ratio. It shows significant advantages in machining processes such as cutting, drilling, and grinding of metal and non-metal materials, and can effectively improve the machining efficiency and accuracy.

[0108] The design method of the present invention has good processability, a simple manufacturing process, and low production costs.

[0109] This ultrasonic horn with a high torsional-longitudinal vibration amplitude ratio has good adaptability. It can flexibly adjust its own state according to different machining process requirements and material characteristics, and has a wide range of applications. In the aerospace field, it is suitable for processing materials such as superalloys and ceramic matrix composites; in the automotive manufacturing field, it can be used for precision machining of metal parts; in the mold manufacturing field, it can meet the processing requirements of complex shapes.

[0110] It is worth emphasizing that, with good energy conversion and transmission performance, for SiC fFor difficult-to-machine materials such as SiC ceramic matrix composites, the horn structure can effectively reduce cutting force and cutting heat, improve the cutting performance of the material, reduce tool wear and breakage, and improve machining efficiency and quality, thereby realizing the high-efficiency and high-precision machining of complex parts, which is in line with the current development trend of energy-efficient machining.

[0111] The above description of the various embodiments of the present application is provided for the purpose of description to those skilled in the art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As described above, various alternatives or variations of the present application will be apparent to those skilled in the art of the above technology. Therefore, although some alternative embodiments have been specifically discussed, other embodiments will be apparent or relatively easy for those skilled in the art to obtain. The present application is intended to cover all alternatives, modifications, and variations of the present invention discussed herein, as well as other embodiments falling within the spirit and scope of the above application.

[0112] Although the present application has been described by way of embodiments, those of ordinary skill in the art know that the present application has many variations and changes without departing from the spirit of the present application, and it is hoped that the appended claims will cover these variations and changes without departing from the spirit of the present application.

Claims

1. An ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio, characterized in that, Including: A piezoelectric ceramic oscillator (3), a horn (2) and a tool tip (1), which are connected in sequence; the inside of the horn is a cavity structure (5), and the wall thickness distribution of the horn is adjustable. By optimizing the internal cavity structure and the wall thickness distribution, the amplitude ratio between the torsional vibration and the longitudinal vibration can be effectively adjusted to achieve the vibration output with a high torsional-longitudinal vibration amplitude ratio.

2. The ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to claim 1, wherein: The ultrasonic horn includes a horn body (4) and a frustum-shaped transition section, and the outer shape of the transition section is formed by rotating a specific geometric curve around the axis.

3. The ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to claim 1, characterized in that: The cavity structure (5) is aligned with the axis of the ultrasonic horn; the cavity structure is a through hole or a blind hole, and its shape is a cavity with a constant diameter along the axis, or a special-shaped cavity formed by rotating a geometric curve around the axis.

4. An ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to claim 1, characterized in that: The horn adjusts the wall thickness distribution by adjusting the cavity structure (5) or the outer peripheral spiral groove (6).

5. An ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to claim 4, characterized in that: The spiral grooves (6) are evenly distributed around the outside of the horn body (4).

6. The design method of an ultrasonic transducer capable of achieving a high torsional vibration-longitudinal vibration amplitude ratio according to claim 1, characterized in that The steps are as follows: Step 1: Select a piezoelectric transducer according to the target frequency f0; for the horn and the front and rear covers of the piezoelectric ceramic oscillator, comprehensively consider the acoustic performance, mechanical performance and stability of the material, and select a metal material that meets the requirements of longitudinal-torsional composite vibration; for the piezoelectric ceramic sheet, combine the target frequency f0 and the performance requirements of the overall transducer, and select the structural dimension parameters of the piezoelectric ceramic sheet; Step 2: Based on the half-wavelength resonance theory or the full-wavelength resonance theory of the selected piezoelectric transducer, combined with the design parameters of the target frequency f0 and the amplitude A, establish a basic structure model of the transducer through the sound velocity characteristic equation; Step 3: Select the outer shape curve of the ultrasonic horn with a high torsional-longitudinal vibration amplitude ratio. The ultrasonic horn includes a cylindrical horn body and a transition section, and the outer shape of the transition section is formed by rotating a logarithmic or exponential geometric curve around the axis; Step 4: Design the spiral groove based on the waveguide parameter adjustment, and determine the groove width characteristic ratio, groove length ratio, spiral angle optimization range and the number of spiral grooves of the spiral groove; convert the longitudinal vibration part transmitted by the ultrasonic vibration transducer into torsional vibration, so as to obtain both longitudinal vibration components and torsional vibration components at the end of the ultrasonic horn; Step 5: Design and adjust the cavity structure and wall thickness of the horn; select the type of cavity structure and the cross-sectional shape of the cavity structure according to the usage scenario requirements of the ultrasonic tool handle. On this basis, optimize the wall thickness gradient to make the horn have good anti-torsion stiffness characteristics, and then effectively optimize the torsional-longitudinal vibration amplitude ratio characteristics of the ultrasonic tool handle to achieve ultrasonic vibration with a high torsional-longitudinal vibration amplitude ratio; Step 6: Based on the structural modal analysis of three-dimensional modeling and finite element simulation, use three-dimensional modeling software to construct a structural model of the ultrasonic transducer; after completing the modeling, use finite element simulation technology to perform structural modal analysis on the model to obtain the resonance frequency, amplitude distribution, node position and torsional-longitudinal amplitude ratio of the horn; Step 7: Based on the simulation data in Step 6, for the modal results that deviate from the design target, optimize the structural dimensions, material layout or constraint conditions until the preset vibration frequency and vibration mode distribution requirements are met.

7. A design method of an ultrasonic transducer capable of achieving a high torsional vibration-longitudinal vibration amplitude ratio according to claim 1, characterized in that, In step 3, the logarithmic and exponential geometric curves are respectively: r(z) = r0e kz , r(z) = r0 + az b .

8. A design method of an ultrasonic transducer capable of achieving a high torsional vibration - longitudinal vibration amplitude ratio according to claim 1, characterized in that, In step 5, (1) select the cavity type according to the scenario requirements: for the high-power long-time working scenario where heat dissipation requirements are prioritized, select the through-hole type cavity with a penetration length L 通孔 satisfying L 通孔 = L 变 ; L 变 is the working length of the horn; for the scenario with high stiffness requirements, select the blind-hole type cavity structure with the blind-hole depth h satisfying: 0.4L 变 ≤ h ≤ 0.9L 变 ; (2) Cavity cross-sectional shape design: A cavity with a constant diameter is used for linear stiffness adjustment, and the diameter d satisfies 0.2D ≤ d ≤ 0.8D, where D is the outer diameter of the horn; a cavity with a variable cross-section is used for non-linear stiffness adjustment, and a logarithmic curve r(z) = r0e kz or an exponential curve r(z) = r0 + az b is generated by rotating around the axis; r0 is the initial radius, and k, a, b are shape coefficients; (3) Gradient wall thickness optimization: First, a theoretical model of the wall thickness is established. Based on the torsional stiffness formula of thin-walled tubes \(K = 2\pi Gt(z) / 3\), a gradient distribution function of the wall thickness \(t(z)\) along the axial direction \(z\) is established: Linear gradient: \(t(z)=t-(t - t)z / L\); Nonlinear gradient: \(t(z)=t+\Delta t\cdot\sin^{2}(\pi z / 2L)\); Then, optimization is carried out under the constraint conditions that the minimum wall thickness \(t\geq c\), where \(c\) is the safety threshold of the yield strength of the material used; and the wall thickness change rate \(|dt / dz|\leq0.3\mathrm{mm / mm}\). 3 / 3, establish the gradient distribution function of the wall thickness \(t(z)\) along the axial direction \(z\): Linear gradient: \(t(z)=t\) max -(t max -t min )z / L 变 ; Nonlinear gradient: \(t(z)=t\) min +\Delta t\cdot\sin^{2}(\pi z / 2L 变 ); Then, under the constraint conditions that the minimum wall thickness \(t\) min \(\geq c\), where \(c\) is the safety threshold of the yield strength of the material used; and the wall thickness change rate \(|dt / dz|\leq0.3\mathrm{mm / mm}\).

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