An ultramagnetostrictive ultrasonic elliptical vibration transducer

Abstract

The application provides a giant magnetostrictive ultrasonic elliptical vibration transducer, which is characterized in that a transverse threaded hole is formed in a conical transition section of a variable amplitude rod, a cylindrical bolt is detachably installed in the threaded hole, and the adjustment of an output elliptical vibration track of the transducer is realized by replacing the cylindrical bolt with a different outer circle diameter through hole. By utilizing the change of vibration energy distribution of the transverse eccentric hole and the regulation of the through hole size on the local mass and stiffness, the flexible adjustment of the elliptical track is realized without changing the main structure of the transducer. On the one hand, the processing adaptability of the single excitation ultrasonic elliptical vibration transducer to different materials and different surfaces is significantly improved, and the operator only needs to replace the cylindrical bolt to meet the processing requirements of different materials or working conditions without disassembling the whole transducer or redesigning and manufacturing. On the other hand, the structure maintains the inherent advantages of the single excitation mode, such as compact structure, low cost and simple control.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic processing technology, and specifically to a supermagnetic-strict ultrasonic elliptical vibration transducer. Background Technology

[0002] With the advancement of science and technology, advanced materials such as titanium alloys, engineering ceramics, carbon fiber composites, and single-crystal silicon have been widely used in many fields such as aerospace, automobiles, and strategic weapons due to their excellent and unique properties. Traditional machining methods can no longer meet the requirements of efficient and high-quality machining of such hard and brittle materials.

[0003] Ultrasonic vibration-assisted machining technology applies high-frequency ultrasonic vibrations to the tool or workpiece, altering the contact state during the cutting process. This effectively reduces cutting forces, decreases cutting heat, and improves the integrity of the machined surface. Ultrasonic elliptical vibration cutting technology causes the tool tip to vibrate along an elliptical trajectory within the cutting plane. During cutting, this not only achieves periodic separation of the tool and chips but also alters the chip flow direction and improves lubrication conditions, further reducing cutting forces and temperatures, and significantly improving machining quality and tool life. Therefore, the ultrasonic elliptical vibration transducer, as the core actuator of this technology, directly impacts the machining effect.

[0004] Currently, there are two main methods for generating ultrasonic elliptical vibration. One method uses two or three sets of excitation electrical signals to drive the excitation element, resulting in complex structures for dual- or triple-excitation ultrasonic vibration transducers and control systems, leading to high control difficulty and unstable performance. The other method uses a single signal to excite the ultrasonic elliptical vibration transducer, causing it to generate elliptical trajectory vibration. This method uses only one set of excitation elements, employing an asymmetric structure on the amplitude transformer to convert longitudinal vibration into bending vibration during transmission, thus synthesizing elliptical trajectory vibration at the output. However, existing single-excitation ultrasonic elliptical vibration transducers share a common technical problem: once the shape of the output elliptical trajectory is determined through structural design, it cannot be changed. In actual machining, different materials or machining conditions require different elliptical trajectories. Elliptical vibration transducers with fixed output trajectories cannot meet the machining needs of different materials and curved surfaces, severely hindering the widespread application of ultrasonic elliptical vibration cutting technology.

[0005] In view of this, the inventors specifically designed a super magnetostrictive ultrasonic elliptical vibration transducer, which led to this invention. Summary of the Invention

[0006] To solve the above problems, the technical solution of the present invention is as follows: A super magnetostrictive ultrasonic elliptical vibration transducer includes a rear cover plate, a super magnetostrictive drive assembly, and an amplitude transformer arranged sequentially. The amplitude transformer includes a flange, a cylindrical section, a conical transition section, and a vibration output section arranged sequentially along the vibration output direction. The conical transition section has a transverse threaded hole, and a cylindrical bolt is detachably installed in the transverse threaded hole. The cylindrical bolt has a through hole along the axial direction. By replacing the cylindrical bolt with a through hole of a different outer circle diameter, the elliptical vibration trajectory output by the transverse threaded hole can be adjusted. The conical transition section has a frustum structure. The end of the conical transition section with a larger diameter is connected to the cylindrical transition section, and the end with a smaller diameter is connected to the vibration output section. The distance between the center line of the transverse threaded hole and the center line of the conical transition section is greater than zero and less than the radius of the vibration output section.

[0007] Preferably, the two ends of the cylindrical bolt are arc-shaped, and after the cylindrical bolt is installed in the transverse threaded hole, its two ends are flush with the outer surface of the conical transition section.

[0008] Preferably, the cross-sectional shape of the through hole of the cylindrical bolt is polygonal or circular.

[0009] Preferably, the diameter of the flange is less than one-quarter wavelength of the vibration frequency of the amplitude transformer.

[0010] Preferably, the diameter of the large end of the conical transition section is smaller than the diameter of the flange, and the diameter of the small end of the conical transition section is 0.3 to 0.5 times the diameter of the large end.

[0011] Preferably, the large end diameter of the vibration output section is the same as the small end diameter of the conical transition section, and the small end diameter of the vibration output section is 0.5 to 0.8 times the large end diameter.

[0012] Preferably, the super magnetostrictive drive assembly includes a magnetically conductive block, a permanent magnet, and a Terfenol-D rod arranged in sequence. A coil is disposed outside the Terfenol-D rod, and a magnetically conductive cylinder and a magnetically conductive sheet are disposed outside the coil.

[0013] Preferably, the rear cover plate, magnetic block, permanent magnet, Terfenol D rod, and amplitude transformer are connected in sequence by pre-tightening bolts.

[0014] The technical solution provided by this invention has the following beneficial effects: This invention features a transverse threaded hole on the conical transition section of the amplitude transformer. A cylindrical bolt with an axially extending through-hole is detachably installed within this hole. The elliptical vibration trajectory of the transducer can be adjusted by replacing the cylindrical bolts with through-holes of different circumscribed circle diameters. By utilizing the alteration of vibration energy distribution through the transverse eccentric hole and the control of local mass and stiffness by the through-hole size, the elliptical trajectory can be flexibly adjusted without altering the main transducer structure or introducing a complex multi-excitation control system. On one hand, this significantly improves the processing adaptability of single-excitation ultrasonic elliptical vibration transducers. Operators can simply replace the bolts to match the processing requirements of different materials or working conditions, without disassembling the entire transducer or redesigning and manufacturing it. On the other hand, this structure retains the inherent advantages of single-excitation methods: compact structure, low processing cost, and simple control. It provides a practical solution for the industrial application of ultrasonic elliptical vibration technology in precision machining. Attached Figure Description

[0015] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0016] in: Figure 1 This invention relates to a super magnetostrictive elliptical vibration transducer. Figure 2 These are the amplitude transformer and the cylindrical bolt; Figure 3 This is the vibration mode diagram of an elliptical vibration transducer; Figure 4 It is the elliptical vibration trajectory output by the transducer; Figure 5 This is a curve showing the relationship between different holes in a cylindrical bolt and the resonant frequency of the transducer. Figure 6 It refers to the different holes of the cylindrical bolt and the longitudinal and lateral displacements output by the transducer.

[0017] Label Explanation: In the diagram: 1. Preload bolt; 2. Rear cover plate; 3. Magnetic guide block; 4. Terfenol-D rod; 7. Magnetic guide sheet; 8. Cylindrical bolt; 81. Hexagonal hole; 82. Cylindrical external thread; 9. Amplitude rod; 91. Flange; 92. Cylindrical transition section; 93. Conical transition section; 94. Vibration output section; 95. Threaded hole; 10. Permanent magnet; 11. Coil; 12. Magnetic guide cylinder; 13. Frame. Detailed Implementation

[0018] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0019] Please see Figures 1-6 This is a preferred embodiment of a magnetostrictive ultrasonic elliptical vibration transducer, comprising a rear cover plate 2, a magnetostrictive drive assembly, and an amplitude transformer 9 arranged sequentially. The amplitude transformer 9 comprises a flange 91, a cylindrical section, a conical transition section 93, and a vibration output section 94 arranged sequentially. The conical transition section 93 has a transverse threaded hole 95, the centerline of which is offset from the centerline of the conical transition section 93. A cylindrical bolt 8 is detachably installed in the transverse threaded hole 95. The cylindrical bolt 8 has a through hole along its axial direction, and in this embodiment, the cross-section of the through hole is a regular hexagon, i.e., the through hole is a hexagonal hole 81. The outer surface of the cylindrical bolt 8 has a cylindrical external thread 82, the diameter of which can be selected according to different processing requirements.

[0020] When the magnetostrictive drive assembly generates longitudinal expansion and contraction vibrations under alternating magnetic field excitation, the asymmetric structure of the amplitude transformer 9, with its off-center transverse threaded hole 95 on the conical transition section 93, disrupts the original axisymmetric geometry of the amplitude transformer 9. When the longitudinal vibration wave passes through this eccentric hole, due to abrupt changes in the local cross-section and uneven mass distribution, some of the longitudinal ultrasonic vibration energy is converted into bending vibration. The superposition of longitudinal and bending vibrations results in a single vibration with an elliptical trajectory at the output end of the amplitude transformer 9. Furthermore, the cylindrical bolt 8 installed in the transverse threaded hole 95 and its inner hole dimensions play a crucial regulatory role in the above coupling process: when the circumscribed circle diameter of the through hole of the cylindrical bolt 8 changes, the local mass and local stiffness at that location change accordingly. Specifically, an increase in the through hole size reduces the equivalent mass and equivalent stiffness at that location, and vice versa. This change in local parameters alters the phase difference and amplitude ratio between the longitudinal and bending waves, directly determining the major and minor axis dimensions and shape of the elliptical trajectory at the output end. Therefore, by simply replacing the cylindrical bolts 8 with through holes of different outer circle diameters, the output elliptical vibration trajectory can be effectively adjusted without changing the main structure of the transducer or introducing a complex multi-excitation control system.

[0021] When adjusting the output elliptical trajectory, the operator simply needs to unscrew the cylindrical bolt 8 with an Allen wrench, replace it with another cylindrical bolt 8 having a through hole with a different circumscribed circle diameter, and then screw it back into the transverse threaded hole 95. Because changing the circumscribed circle diameter of the through hole adjusts the local mass and stiffness distribution of the conical transition section 93 of the amplitude transformer 9, it affects the coupling degree of longitudinal and bending vibrations, ultimately causing the transducer output end to synthesize elliptical vibration trajectories with different major and minor axis ratios.

[0022] Please see Figures 1-6 The conical transition section 93 has a frustum structure. The larger diameter end of the conical transition section 93 connects to the cylindrical transition section 92, which is connected to the flange 91. The smaller diameter end of the cylindrical transition section 92 connects to the vibration output section 94. The centerline of the transverse threaded hole 95 deviates from the centerline of the conical transition section 93 by a distance greater than zero and less than the radius of the vibration output section 94. Due to the eccentricity of the transverse threaded hole 95 relative to the centerline of the conical transition section 93, the amplitude transformer 9 loses its axisymmetry at this position, forming a structural asymmetry region. When the longitudinal vibration wave is transmitted along the amplitude transformer 9 to the position of the eccentric threaded hole 95, due to abrupt changes in the local cross-section and asymmetric mass distribution, the longitudinal vibration is converted into bending vibration. The longitudinal and bending vibrations are superimposed at the output end to synthesize an elliptical trajectory vibration. Simultaneously, the deviation distance is limited to a range greater than zero and less than the radius of the vibration output section 94, ensuring that the eccentricity is sufficient to excite an effective bending vibration component without excessive energy dissipation or insufficient structural strength due to excessive eccentricity. By limiting the eccentricity within a reasonable range, the transducer is able to output elliptical trajectory vibration stably and efficiently, providing a structural basis for further adjustment of the elliptical trajectory by replacing cylindrical bolts 8 with different inner hole sizes.

[0023] Please see Figures 1-6The cylindrical bolt 8 has two ends machined into arc shapes. When the cylindrical bolt 8 is installed in the transverse threaded hole 95 of the conical transition section 93 of the amplitude transformer 9 via threaded engagement, the arc-shaped surfaces at both ends are flush with the outer surface of the conical transition section 93, forming a continuous and smooth profile. By designing the bolt ends to be arc-shaped with the curvature of the generatrix of the conical transition section 93 and precisely matching the installation depth, the bolt is completely embedded within the profile of the amplitude transformer 9 body without any protrusions or depressions. On the one hand, this ensures the geometric continuity of the outer surface of the amplitude transformer 9, allowing longitudinal vibration and bending vibration waves to smoothly transition when passing through this position, reducing unnecessary reflection and scattering, and lowering energy loss. On the other hand, it avoids the risk of local fretting wear or loosening that may occur under high-frequency vibration due to protruding structures, improving the structural stability and service life of the transducer during long-term continuous operation.

[0024] Please see Figures 1-6 The through hole of the cylindrical bolt 8 along the axial direction has a cross-sectional shape that is not limited to a regular hexagon, but can be any of a polygon (such as a regular hexagon, rectangle, triangle, etc.) or a circle. By adopting the above-mentioned multiple shape design, the problems of limited processing adaptability and high mold and tool costs caused by the single shape of the through hole in the prior art are effectively solved. Regardless of the shape of the through hole, by replacing the cylindrical bolt 8 with different characteristic dimensions (i.e., different circumscribed circle diameters or different circular hole diameters), the local mass and stiffness distribution at the eccentric position of the conical transition section 93 of the amplitude transformer 9 can be changed, thereby adjusting the phase difference and amplitude ratio between longitudinal vibration and bending vibration, and finally achieving effective control of the major and minor axis dimensions of the output elliptical trajectory.

[0025] Please see Figures 1-6 The diameter of the flange 91 is smaller than one-quarter wavelength of the vibration frequency of the amplitude transformer 9. Based on the transducer's design operating frequency, the longitudinal wave wavelength of this frequency in the amplitude transformer 9 material is calculated, and the diameter of the flange 91 is controlled within one-quarter wavelength. Since the flange 91 serves as the connecting component between the transducer and the external support, a diameter smaller than one-quarter wavelength reduces the transverse vibration of the transducer and suppresses the loss of ultrasonic vibration energy.

[0026] Please see Figures 1-6The large-end diameter of the conical transition section 93 is smaller than the diameter of the flange 91, and the small-end diameter of the conical transition section 93 is 0.3 to 0.5 times the large-end diameter, which is 0.4 times in this embodiment. By designing the large-end diameter to be smaller than the flange 91 diameter, it is ensured that the conical transition section 93 can naturally contract from the cylindrical section (whose diameter is comparable to or slightly smaller than that of the flange 91), avoiding reflection and energy loss caused by abrupt changes in cross-section. At the same time, controlling the small-end diameter within the range of 0.3 to 0.5 times the large-end diameter ensures that the conical transition section 93 has a suitable taper. If the taper is too small (the small-end diameter is too large), the amplitude amplification effect will be insignificant; if the taper is too large (the small-end diameter is too small), it will cause a sharp increase in local stress and make it difficult to effectively excite the bending vibration component. This preferred ratio range ensures both a sufficient longitudinal amplitude amplification factor and provides a reasonable cross-sectional change gradient for the longitudinal bending coupling at the eccentric threaded hole 95.

[0027] Please see Figures 1-6 The large end diameter of the vibration output section 94 is set to be the same as the small end diameter of the conical transition section 93 to ensure a continuous and smooth transition of the cross-section of the amplitude transformer 9 at this connection. Simultaneously, the small end diameter of the vibration output section 94 is limited to 0.5 to 0.8 times the large end diameter; in this embodiment, it is 0.7 times. The vibration output section 94 is designed as a stepped cylindrical structure, with its large end and the small end of the conical transition section 93 connected at the same diameter. The subsequent reduction in diameter by 0.5 to 0.8 times provides a certain amplitude amplification effect to the output section. This preferred ratio range allows the vibration output section 94 to effectively concentrate energy to the small end face while maintaining sufficient longitudinal stiffness, achieving efficient energy output to the processing area.

[0028] Please see Figures 1-6 The total length of the amplitude transformer 9 is greater than one-quarter wavelength and less than one-half wavelength corresponding to its vibration frequency. Based on the longitudinal wave wavelength of the vibration frequency in the material of the amplitude transformer 9, the total length of the amplitude transformer 9 is designed to be between one-quarter and one-half wavelength.

[0029] Please see Figures 1-6The magnetostrictive drive assembly includes a magnetically conductive block 3, a permanent magnet 10, and a Terfenol-D rod 4 arranged sequentially. A coil 11 is disposed outside the Terfenol-D rod 4, and a magnetically conductive cylinder 12 and a magnetically conductive sheet 7 are disposed outside the coil 11. The rear cover plate 2, the magnetically conductive block 3, the permanent magnet 10, the Terfenol-D rod 4, and the amplitude transformer 9 are connected sequentially by pre-tightening bolts 1. By sequentially placing the permanent magnet 10 and the magnetically conductive block 3 at both ends of the Terfenol-D rod 4, a bias magnetic field and a magnetic path are provided. The coil 11 is placed outside the Terfenol-D rod 4 and wound around the frame 13. The magnetically conductive cylinder 12 and the magnetically conductive sheet 7 are disposed outside the coil 11, forming a closed magnetic circuit, which significantly reduces leakage flux and improves magnetic field utilization efficiency.

[0030] The vibration performance of the amplitude transformer 9 in the transducer of this invention was experimentally verified. Specifically, the amplitude transformer 9 is made of aluminum alloy. The diameter of the flange 91 is 63 mm and the length is 5 mm. The diameter of the cylindrical section immediately following the flange 91 is 52 mm and the length is 7 mm. The diameter of the small end of the conical transition section 93 is 25 mm and the length is 21 mm. The large end of the vibration output section 94 has a diameter of 25 mm and a length of 20 mm. The small end has a diameter of 15 mm and a length of 52 mm. The center of the threaded hole 95 on the amplitude transformer 9 is 10 mm away from the center line of the amplitude transformer 9. The diameter of the threaded hole 95 is 9 mm. The outer circle diameter of the hexagonal hole 81 is 8 mm. The Terfenol-D rod 4 is made of terbium-dysprosium iron, with an outer diameter of 15mm and a length of 35mm; the permanent magnet 10 is made of neodymium iron boron, with an outer diameter of 15mm and a length of 3mm; the magnetic conductor 3 is made of electrical pure iron, with an outer diameter of 15mm and a length of 5mm; the rear cover plate 2 is made of 316 stainless steel, with an outer diameter of 38mm and a length of 35mm; the excitation coil 11 has 350 turns and an excitation voltage of 100V. Finite element dynamics calculations were performed on the transducer using COMSOL to obtain... Figure 3 The vibration mode of the elliptical vibration transducer is longitudinal bending vibration, and the resonant frequency is 19986Hz. Figure 4 The elliptical vibration trajectories output by the transducers under cylindrical bolts 8 with different circumscribed circle diameters are shown, where... Figure 4 In the figure, a, b, c, and d represent the elliptical trajectories when the circumscribed circle radii are 2mm, 4mm, 6mm, and 8mm, respectively. The elliptical trajector output trajectories differ depending on the circumscribed circle diameter of the hexagonal hole 81 in the cylindrical bolt 8, thus enabling the control of the output trajectory. Figure 5 The curves show the relationship between the circumscribed circle radius of different hexagonal holes 81 and the resonant frequency of the transducer. As the circumscribed circle radius increases, the resonant frequency of the transducer decreases. Figure 6 For different circumscribed circle radii and transverse displacements of the transducer output, as the circumscribed circle radius increases, the longitudinal displacement of the transducer output decreases and the transverse displacement increases.

[0031] In summary, this invention provides a transverse threaded hole 95 on the conical transition section 93 of the amplitude transformer 9. A cylindrical bolt 8 with an axially through hole is detachably installed in the hole. The elliptical vibration trajectory of the transducer can be adjusted by replacing the cylindrical bolts 8 with through holes of different circumscribed circle diameters. By utilizing the alteration of vibration energy distribution through the transverse eccentric hole and the control of local mass and stiffness by the through hole size, the elliptical trajectory can be flexibly adjusted without changing the main structure of the transducer or introducing a complex multi-excitation control system. On the one hand, this significantly improves the processing adaptability of the single-excitation ultrasonic elliptical vibration transducer. Operators only need to simply replace the bolts to match the processing requirements of different materials or working conditions, without disassembling the entire transducer or redesigning and manufacturing it. On the other hand, this structure maintains the inherent advantages of single-excitation methods: compact structure, low processing cost, and simple control. This provides a practical solution for the industrial promotion of ultrasonic elliptical vibration technology in the field of precision machining.

[0032] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A giant magnetostrictive ultrasonic elliptical vibration transducer, comprising a rear cover plate, a giant magnetostrictive drive assembly, and an amplitude transformer arranged sequentially, characterized in that, The amplitude transformer includes a flange, a cylindrical transition section, a conical transition section, and a vibration output section arranged sequentially along the vibration output direction. The conical transition section has a transverse threaded hole, and a cylindrical bolt is detachably installed in the transverse threaded hole. The cylindrical bolt has a through hole along the axial direction. By replacing the cylindrical bolt with a through hole of a different outer circle diameter, the elliptical vibration trajectory output by the transverse threaded hole can be adjusted. The conical transition section has a frustum structure. The end of the conical transition section with a larger diameter is connected to the cylindrical transition section, and the end with a smaller diameter is connected to the vibration output section. The distance between the center line of the transverse threaded hole and the center line of the conical transition section is greater than zero and less than the radius of the vibration output section.

2. The supermagnetic-strict ultrasonic elliptical vibration transducer according to claim 1, characterized in that, The cylindrical bolt has two arc-shaped ends. After the cylindrical bolt is installed in the transverse threaded hole, its two ends are flush with the outer surface of the conical transition section.

3. The supermagnetic-strict ultrasonic elliptical vibration transducer according to claim 1, characterized in that, The cross-sectional shape of the through hole of the cylindrical bolt is polygonal or circular.

4. The supermagnetic-strict ultrasonic elliptical vibration transducer according to claim 1, characterized in that, The diameter of the flange is less than one-quarter of the wavelength corresponding to the vibration frequency of the amplitude transformer.

5. A supermagnetically tightening ultrasonic elliptical vibration transducer according to claim 1, characterized in that, The large end diameter of the conical transition section is smaller than the diameter of the flange, and the small end diameter of the conical transition section is 0.3 to 0.5 times the large end diameter.

6. The supermagnetic-strict ultrasonic elliptical vibration transducer according to claim 1, characterized in that, The large end diameter of the vibration output section is the same as the small end diameter of the conical transition section, and the small end diameter of the vibration output section is 0.5 to 0.8 times the large end diameter.

7. The supermagnetic-strict ultrasonic elliptical vibration transducer according to claim 1, characterized in that, The super magnetostrictive drive assembly includes a magnetically conductive block, a permanent magnet, and a Terfenol-D rod arranged in sequence. A coil is disposed outside the Terfenol-D rod, and a magnetically conductive cylinder and a magnetically conductive sheet are disposed outside the coil.

8. A supermagnetically tightening ultrasonic elliptical vibration transducer according to claim 7, characterized in that, The rear cover plate, magnetic block, permanent magnet, Terfenol-D rod, and amplitude transformer are connected in sequence by pre-tightening bolts.

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