Ultrasonic amplitude-change pole and ultrasonic vibrator for high-temperature and strong-electromagnetic-field environment

Abstract

The invention discloses an ultrasonic amplitude transformer and an ultrasonic vibrator for a high-temperature and strong electromagnetic field environment, and belongs to the technical field of microstructure hot press molding. The ultrasonic amplitude transformer for the high-temperature and strong-electromagnetic-field environment comprises a ceramic section and a connecting section, the ceramic section and the connecting section are connected through a middle section, the connecting section is connected with a transducer, and the ceramic section, the middle section and the connecting section are linearly arranged and coaxially arranged. The lengths of the ceramic section, the middle section and the connecting section are integral multiples of half wavelength, and the diameters of the ceramic section, the middle section and the connecting section are smaller than 1 / 4 wavelength. The ultrasonic amplitude-change pole can normally work in a microwave electromagnetic field of 2.45 GHz and 1.5 kW, the vibration frequency drift at the high temperature of 800 DEG C is reduced by 1.2%, and the amplitude is reduced by 1.61 [mu] m. By adopting the ultrasonic amplitude transformer and the ultrasonic vibrator used for the high-temperature and strong-electromagnetic-field environment, the problems that an existing all-metal ultrasonic amplitude transformer is insufficient in stability at the high temperature and poor in adaptability to the strong-electromagnetic-field environment can be solved; the hot-press forming precision of the microstructure is improved, and the application boundary of an ultrasonic vibration system is expanded.

Description

Technical Field

[0001] This invention relates to the field of microstructure hot pressing technology, and in particular to an ultrasonic amplitude transformer and ultrasonic transducer for use in high temperature and strong electromagnetic field environments. Background Technology

[0002] The ultrasonic amplitude transformer is a core component of an ultrasonic vibration system, playing a crucial role in transmitting mechanical vibration energy and amplifying amplitude. It is widely used in high-temperature extreme conditions such as metal welding, metal smelting, nuclear reactions, and hot pressing. However, commonly used ultrasonic amplitude transformers are mostly made of metal materials such as aluminum alloys, carbon steel, and titanium alloys. Under continuous high-temperature environments, these materials are prone to changes in properties and thermal expansion deformation, leading to frequency drift. This frequency drift further causes detuning of the entire ultrasonic vibration system, resulting in reduced energy efficiency or even equipment damage, severely impacting practical application performance. Although measures such as adding cooling tanks or introducing length compensation can partially mitigate the effects of high temperatures, traditional ultrasonic amplitude transformers are still difficult to adapt to the demands of continuous high-temperature operations due to the inherent temperature sensitivity and high coefficient of thermal expansion of metallic materials. This is especially true for the hot pressing of microstructures, where the frequency and amplitude stability of the ultrasonic amplitude transformer have a significant impact on the forming accuracy due to the small size of the microstructures. High temperatures easily cause frequency and amplitude shifts and system detuning in traditional metal amplitude transformers, severely affecting the hot pressing effect of microstructure components.

[0003] Furthermore, in special working environments with strong electromagnetic fields, the conductivity of traditional metal ultrasonic amplitude transformers can lead to eddy currents and electromagnetic interference, further limiting their application range. Therefore, there is an urgent need to develop a high-temperature resistant and electromagnetic interference-resistant ultrasonic amplitude transformer to improve the vibration stability and reliability of ultrasonic vibration systems under extreme conditions. Summary of the Invention

[0004] The purpose of this invention is to provide an ultrasonic amplitude transformer and ultrasonic transducer for use in high-temperature and strong electromagnetic field environments, solving the problems of poor stability of existing ultrasonic amplitude transformers at high temperatures and poor adaptability to strong electromagnetic field environments, which affect the accuracy of microstructure hot pressing.

[0005] To achieve the above objectives, the present invention provides an ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments, comprising a ceramic segment and a connecting segment, wherein the ceramic segment and the connecting segment are connected by an intermediate segment, and the connecting segment is connected to a transducer. The ceramic segment, the intermediate segment and the connecting segment are arranged linearly and coaxially, and the ceramic segment is made of a low dielectric loss ceramic material.

[0006] Preferably, the ceramic section is pressureless sintered alumina (Al2O3) ceramic, the connecting section is D2 tool steel, and the intermediate section is 316L stainless steel.

[0007] Preferably, the intermediate section and the ceramic section are connected by a double-ended stud.

[0008] Preferably, the connecting section and the intermediate section are connected by threads or studs.

[0009] Preferably, the lengths of the connecting segment, the intermediate segment, and the ceramic segment are: ,in For length, For the corresponding longitudinal wave velocity in the material, To set the frequency, It is an integer.

[0010] Preferably, the connecting segment includes a first segment and a second segment arranged coaxially. The connecting segment is connected to the middle segment through the second segment. A flange is provided between the first segment and the second segment to facilitate the installation and positioning of the ultrasonic amplitude transformer. The flange is located at the center of the connecting segment.

[0011] Preferably, the diameters of the connecting segment, the intermediate segment, and the ceramic segment are: ,in For diameter, For the corresponding longitudinal wave velocity in the material, To set the frequency.

[0012] Preferably, the diameter of the first segment is larger than the diameter of the second segment, and the diameter of the middle segment is larger than the diameter of the ceramic segment.

[0013] An ultrasonic transducer includes the aforementioned ultrasonic amplitude transformer and transducer. The transducer includes a rear cover plate and a front cover plate. A piezoelectric element is disposed between the rear cover plate and the front cover plate. The piezoelectric element includes a plurality of stacked piezoelectric ceramics. The piezoelectric ceramics are connected by bolts with axial preload. The density of the front cover plate is lower than that of the rear cover plate.

[0014] Preferably, the front cover is made of 45 steel, the rear cover is made of LY12 aluminum alloy, and the piezoelectric element is PZT-8 piezoelectric ceramic.

[0015] The advantages and positive effects of the ultrasonic amplitude transformer and ultrasonic transducer for high temperature and strong electromagnetic field environments described in this invention are as follows: The ultrasonic amplitude transformer of this invention has an Al2O3 ceramic segment at its end. The Al2O3 ceramic segment possesses high thermal stability and a low coefficient of thermal expansion, overcoming the temperature sensitivity of traditional all-metal ultrasonic amplitude transformers at the material level. This ultrasonic amplitude transformer can operate continuously at high temperatures for extended periods, effectively resisting material modification and thermal expansion deformation, thereby stabilizing its resonant frequency at a preset operating point. This avoids system detuning and energy efficiency attenuation caused by frequency drift, effectively improving the precision of plastic microforming.

[0016] The ultrasonic amplitude transformer described in this invention has an Al2O3 ceramic segment at its end. The Al2O3 ceramic segment possesses electrical insulation and low dielectric loss characteristics, does not generate eddy currents or cause electromagnetic interference in strong electromagnetic field environments, and has a low electromagnetic energy absorption rate. These characteristics make the ultrasonic amplitude transformer suitable for industrial scenarios with strong electromagnetic fields, such as microwave ovens, induction heating furnaces, and plasma sintering furnaces, thus expanding the application range of ultrasonic vibration systems.

[0017] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the ultrasonic transducer of the present invention; Figure 2 This is a schematic diagram of the transducer structure of the present invention; Figure 3 The following are the finite element modal analysis results of the ultrasonic transducer in this embodiment at room temperature; (a) is the longitudinal vibration mode cloud diagram of the ultrasonic amplitude transformer in this embodiment at room temperature; (b) is the structural and electrical connection schematic diagram of the ultrasonic transducer in this embodiment; and (c) is the amplitude-frequency response curve of the input / output terminal. Figure 4 The following are the finite element modal analysis results of the ultrasonic transducer in the embodiment of the present invention at high temperature; (a) and (b) are temperature distribution cloud maps of Al2O3 and Ti-6Al-4V amplitude transformers at the end temperature of 800℃, respectively; (c) and (d) are axial thermal deformation cloud maps of Al2O3 and Ti-6Al-4V amplitude transformers, respectively. Figure 5 The following are amplitude-frequency diagrams from the finite element simulation of the ultrasonic transducer in this embodiment of the invention: (a) shows the vibration response of the Al2O3 amplitude transformer at room temperature and at a terminal temperature of 800°C; (b) shows the vibration response of the Ti-6Al-4V amplitude transformer at room temperature and at a terminal temperature of 800°C. Figure 6 This is a schematic diagram of the room temperature modal experiment of the ultrasonic transducer according to an embodiment of the present invention; (a) is the experimental setup, (b) is a typical periodic vibration signal at the output end of the ultrasonic amplitude transformer, and (c) is the output amplitude of the ultrasonic transducer at different powers.

[0019] Figure 7 (a) is a schematic diagram of the high-temperature modal experiment of the ultrasonic transducer in an embodiment of the present invention; (b) is a schematic diagram of the microwave heating system; and (c) shows the vibration frequency and amplitude measured at different temperatures. Figure 8 The diagram shows the admittance characteristics of the ultrasonic transducer measured at high temperature according to an embodiment of the present invention; (a) is the susceptance-conductance curve; (b) is the admittance-frequency curve. Figure 9The diagram shows an ultrasonic vibration-assisted microimprinting experiment according to an embodiment of the present invention; (a) shows the PMMA preform and SiC mold, (b) shows the PMMA micro-bump array replicated by conventional imprinting, and (c) shows the PMMA micro-bump array replicated by ultrasonic vibration-assisted microimprinting according to this embodiment. Figure 10 The following are comparative images of the surface morphology of the microstructure in the embodiments of the present invention: (a) is the microgroove array on the surface of the SiC lower mold, (b) is the surface morphology of the conventionally imprinted PMMA replica, (c) is the surface morphology of the ultrasonically assisted imprinted PMMA replica in this embodiment, and (d) is a comparative image of the cross-sectional contour of the SiC lower mold and the PMMA replica in this embodiment.

[0020] Figure Labels 1. Connecting section; 11. First section; 12. Second section; 2. Middle section; 3. Ceramic section; 4. Rear cover plate; 5. Piezoelectric element; 6. Front cover plate; 7. Bolt. Detailed Implementation

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] In this application, 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 application pertains. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit the scope of this application.

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] like Figure 1As shown, an ultrasonic amplitude transformer for high-temperature and strong electromagnetic field environments includes a ceramic section 3 and a connecting section 1, with the ceramic section 3 and the connecting section 1 connected by an intermediate section 2. The connecting section 1 is connected to a transducer, realizing the connection between the ultrasonic amplitude transformer and the transducer. The ceramic section 3, the intermediate section 2, and the connecting section 1 are arranged linearly and coaxially.

[0025] Preferably, ceramic segment 3 is pressureless sintered alumina ceramic with a purity ≥99.5%. Alumina ceramics possess a high Young's modulus (~392 GPa) and a low coefficient of thermal expansion (<9 × 10⁻⁶). -6 The high temperature resistance (>1000℃) and high thermal conductivity ( / K) of the ultrasonic amplitude transformer enhance its high-temperature performance. Alumina ceramics possess excellent electrical insulation and low dielectric loss characteristics, do not induce eddy currents or electromagnetic interference, and exhibit extremely low electromagnetic wave energy absorption. These properties make the ultrasonic amplitude transformer suitable for use in strong electromagnetic environments such as microwave ovens, induction heating furnaces, and plasma sintering furnaces, thus expanding its application range.

[0026] Connecting section 1 is made of D2 tool steel, and intermediate section 2 is made of 316L stainless steel. Intermediate section 2 and ceramic section 3 are connected by double-ended studs, facilitating the installation, removal, and replacement of ceramic section 3. Connecting section 1 and intermediate section 2 are also connected by threads. This threaded or studded connection facilitates the installation and removal of the ultrasonic amplitude transformer, making it easy to replace both connecting section 1 and ceramic section 3, thus reducing costs.

[0027] The connecting section 1 includes a first section 11 and a second section 12 arranged coaxially, and the connecting section 1 is connected to the intermediate section 2 through the second section 12. A flange is provided between the first section 11 and the second section 12 to facilitate the installation of the ultrasonic amplitude transformer, and the flange is located at the center of the connecting section 1. Setting the flange in the center helps to reduce the amplitude at the flange and improve the stability of the ultrasonic amplitude transformer connection.

[0028] The lengths of connecting segment 1, intermediate segment 2, and ceramic segment 3 are: ,in For length, To correspond to the longitudinal wave velocity in the material, To set the frequency, The length of each segment of the ultrasonic amplitude transformer is set to an integer multiple of the half-wavelength of the longitudinal wave under the target ultrasonic wave, so as to achieve resonance at the target frequency.

[0029] The diameters of connecting section 1, intermediate section 2, and ceramic section 3 are ,in For diameter, To correspond to the longitudinal wave velocity in the material, To set the frequency, setting the diameter of each segment to be less than 1 / 4 of the wavelength of the material at the target frequency can effectively suppress lateral vibration and improve the stability of longitudinal vibration.

[0030] The diameter of the first segment 11 is larger than the diameter of the second segment 12, and the diameter of the middle segment 2 is larger than the diameter of the ceramic segment 3. Setting the ultrasonic amplitude transformer to have unequal diameters is beneficial for concentrating vibration energy and amplifying the amplitude.

[0031] like Figure 2 As shown, the ultrasonic transducer includes the aforementioned ultrasonic amplitude transformer and transducer. The ultrasonic amplitude transformer is fixedly connected to the transducer via the first segment 11. The transducer includes a rear cover plate 4 and a front cover plate 6. A piezoelectric element 5 is disposed between the rear cover plate 4 and the front cover plate 6. The piezoelectric element 5 includes several stacked piezoelectric ceramics, which are connected by bolts 7 with axial preload. The bolts 7 are M12 45 steel bolts, which fix the rear cover plate 4, the front cover plate 6, and the piezoelectric element 5 together.

[0032] The density of the front cover plate 6 is lower than that of the rear cover plate 4. The front cover plate 6 is made of 45 steel, the rear cover plate 4 is made of LY12 aluminum alloy, and the piezoelectric element 5 is a transmitting type PZT-8 piezoelectric ceramic.

[0033] Example The target frequency set in this embodiment is 19.5kHz. Take 1. The length of the connecting section 1 of the ultrasonic amplitude transformer. The length of the middle section 2 is 133.90 mm. The length of ceramic segment 3 is 126.34 mm. It is 254.28 mm. The length of the first segment 11 is equal to the length of the second segment 12. The diameter of the first segment 11 is... The diameter of the second segment is 54mm, and the diameter of segment 12 is 12mm. The diameter of the middle section 2 is 31mm. The diameter of ceramic segment 3 is 32mm. It is 30mm.

[0034] The diameters of the front cover plate 6 and the rear cover plate 4 in the ultrasonic transducer are both 50 mm, and the length of the front cover plate 6 is... =65.69mm, rear cover plate length 4 =28.29mm.

[0035] Modal analysis of the ultrasonic transducer in the embodiment was performed using the finite element method, such as... Figure 3 As shown. Figure 3As shown in (c), at room temperature, the first-order longitudinal vibration mode frequency of the ultrasonic transducer is 19.490 kHz, which deviates from the design frequency of 19.5 kHz by only 0.46%, verifying the correctness of the design. Frequency domain analysis shows that at the resonant point, the maximum amplitude at the output end of ceramic segment 3 can reach 5.62 μm, with an amplification factor of 3.49.

[0036] High-temperature modal analysis was performed on the ultrasonic transducer to simulate the vibration characteristics of the amplitude transformer end under heating at 800℃. For example... Figure 4 As shown, the high-temperature zone of the amplitude transformer in this embodiment is smaller, and the axial thermal deformation (0.588 mm) is significantly smaller than that of the Ti-6Al-4V amplitude transformer (0.891 mm). Figure 5 The amplitude spectrum of the ultrasonic transducer in the embodiment of the present invention is shown below. Figure 5 As shown, when the temperature rises from 25℃ to 800℃, the resonant frequency of the amplitude transformer in this embodiment decreases by 238Hz (only 1.2% of the initial value), and the amplitude decreases by 1.61μm; while the resonant frequency of the Ti-6Al-4V amplitude transformer decreases by 982Hz, and the amplitude decreases by 12.55μm, indicating that the amplitude transformer described in this embodiment of the invention has excellent high-temperature stability.

[0037] An experimental system was built for testing. The experimental system is as follows: Figure 6 As shown in (a). Figure 6 As shown in (c), at room temperature and 40% ultrasonic power, the measured output amplitude of the amplitude transformer in this embodiment is 5.20 μm, which agrees well with the simulation result of 5.62 μm. Using the following... Figure 7 The microwave heating system shown in (a) was used for a high-temperature experiment. The microwave frequency was 2.45 GHz and the microwave power was 1.5 kW. Figure 7 As shown in (b), the results indicate that the frequency and amplitude decrease slowly with increasing temperature, a trend consistent with the simulation results. Figure 8 As shown in (b), the resonant frequency was measured to be 19.216 kHz at 800 °C, and the mechanical quality factor was... Q m Reaching 2135. For example... Figure 8 As shown in (a), the admittance trajectory is a single circular ring with no stray mode coupling, indicating that the ultrasonic transducer can work stably in both room temperature and high temperature environments.

[0038] The ultrasonic-assisted system described in this embodiment was used for PMMA microimprinting experiments. The heating system is... Figure 7 (a) The microwave heating system is configured with a microwave frequency of 2.45 GHz and a microwave power of 1.5 kW. The ultrasonic-assisted system is as follows: Figure 6As shown in (a), the vibration frequency was set to 19.385 kHz and the amplitude to 5.05 μm. The experimental sample was a PMMA preform with dimensions of 14 mm × 14 mm × 4 mm; both the upper and lower molds were made of SiC ceramic with high microwave absorptivity, and the surface of the lower mold had a microgroove array structure, such as... Figure 9 As shown in (a), the imprinting process parameters are: temperature 170℃, imprinting speed 0.06 mm / s, imprinting displacement 1.20 mm, holding pressure 100 N, holding time 300 s; after holding, the PMMA is cooled to room temperature at a rate of 10℃ / s and then demolded.

[0039] Imprinting test results are as follows Figure 9 and Figure 10 As shown. By Figure 9 (c) Figure 10 (c) and Figure 10 (d) As can be seen, the ultrasonic amplitude transformer described in this invention successfully replicated a micro-protrusion array with a clear outline, and its cross-sectional profile has a good fit with the mold groove. Quantitative analysis showed that the average filling rate of PMMA in ultrasonic vibration-assisted imprinting reached 96.79%, which is 10.72% higher than the 86.07% of conventional imprinting. This indicates that the ultrasonic amplitude transformer described in this embodiment still has excellent working performance under extreme environments such as high temperature and strong microwave electromagnetic fields.

[0040] In summary, the ultrasonic amplitude transformer and ultrasonic transducer proposed in this invention for high temperature and strong electromagnetic field environments can effectively solve the problems of insufficient stability of existing ultrasonic amplitude transformers under high temperature conditions and poor adaptability to strong electromagnetic field environments, thereby improving the precision of microstructure hot pressing.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An ultrasonic amplitude transformer for use in high-temperature and strong electromagnetic field environments, characterized in that: It includes a ceramic segment and a connecting segment. The ceramic segment and the connecting segment are connected by an intermediate segment. The connecting segment is connected to the transducer. The ceramic segment, intermediate segment and connecting segment are arranged linearly and coaxially. The ceramic segment is made of low dielectric loss ceramic material.

2. The ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 1, characterized in that: The ceramic section is pressureless sintered alumina ceramic, the connecting section is D2 tool steel, and the intermediate section is 316L stainless steel.

3. An ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 1, characterized in that: The middle section and the ceramic section are connected by double-ended studs.

4. An ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 1, characterized in that: The connecting section and the intermediate section are connected by threads or studs.

5. An ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 1, characterized in that: The lengths of the connecting section, the intermediate section, and the ceramic section are: ,in For length, For the corresponding longitudinal wave velocity in the material, To set the frequency, It is an integer.

6. An ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 1, characterized in that: The connecting section includes a first section and a second section arranged coaxially. The connecting section is connected to the middle section through the second section. A flange is provided between the first section and the second section to facilitate the installation and positioning of the ultrasonic amplitude transformer. The flange is located at the center of the connecting section.

7. An ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 6, characterized in that: The diameters of the connecting section, the intermediate section, and the ceramic section are: ,in For diameter, For the corresponding longitudinal wave velocity in the material, To set the frequency.

8. An ultrasonic amplitude transformer for high temperature and strong electromagnetic field environments according to claim 7, characterized in that: The diameter of the first segment is larger than the diameter of the second segment, and the diameter of the middle segment is larger than the diameter of the ceramic segment.

9. An ultrasonic transducer, characterized in that: The invention includes the ultrasonic amplitude transformer and transducer as described in any one of claims 1-8. The transducer includes a rear cover plate and a front cover plate. A piezoelectric element is disposed between the rear cover plate and the front cover plate. The piezoelectric element includes a plurality of stacked piezoelectric ceramics. The piezoelectric ceramics are connected by bolts with axial preload. The density of the front cover plate is lower than that of the rear cover plate.

10. An ultrasonic transducer according to claim 9, characterized in that: The front cover is made of 45 steel, the rear cover is made of LY12 aluminum alloy, and the piezoelectric element is PZT-8 piezoelectric ceramic.

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