A method and apparatus for ultrasonic vibration assisted superplastic forming of titanium alloys

Abstract

This invention relates to the field of superplastic forming, and particularly to a method and apparatus for ultrasonic vibration-assisted superplastic forming of titanium alloys. Step S1: Select the vibration frequency of the ultrasonic generator according to the type, thickness, size, and forming shape of different titanium alloy sheets; adjust the vibration amplitude of the ultrasonic vibration; and generate a suitable ultrasonic vibration mode by changing the transducer or amplitude transformer. Adjust the heating temperature, heating time, and output pressure of the gas source system of the heating furnace. This invention incorporates ultrasonic vibration-assisted forming during the superplastic forming process of titanium alloys. Under the combined action of high-pressure argon gas and ultrasonic vibration, the high-temperature yield strength and flow stress of the titanium alloy sheet, which has reached superplasticity after heating, are reduced, shortening the superplastic forming cycle. Applying ultrasonic vibration during the forming process improves its mold adhesion, thereby increasing the contour accuracy of the formed parts and the yield rate of the finished products.

Description

Technical Field

[0001] This invention relates to the field of superplastic forming, and in particular to a method and apparatus for ultrasonic vibration-assisted superplastic forming of titanium alloys. Background Technology

[0002] Titanium alloys, as materials with lightweight, high strength, and corrosion resistance, are widely used in aerospace, automotive, and medical device industries. However, due to their high melting point and difficulty in processing, traditional forming methods such as forging or machining have certain limitations. This is where titanium alloy superplastic forming technology plays a crucial role. Titanium alloy superplastic forming is a forming technology that involves heating titanium alloy materials at high temperatures, causing them to be formed into complex shapes under pressure and molds in a superplastic state.

[0003] The advantages of titanium alloy superplastic forming include the ability to create complex geometries, improved material utilization, reduced machining steps, and increased production efficiency. However, the process of titanium alloy superplastic forming is highly complex, requiring strict control of parameters such as temperature, pressure, and time to ensure product quality. Several common problems and challenges may be encountered during the titanium alloy superplastic forming process, including:

[0004] Defects and cracks: Due to the high-temperature deformation characteristics and microstructure sensitivity of titanium alloys, improper forming conditions or excessive deformation stress may lead to defects, cracks or fractures in the parts.

[0005] Uneven thickness distribution: During superplastic forming, due to the fluidity and deformation capacity of the material, the thickness of some areas may change, resulting in uneven thickness distribution of the part.

[0006] Surface quality and precision requirements: The surface quality and dimensional accuracy of titanium alloy superplastic formed parts are critical for many applications. Due to high-temperature deformation and flowability, problems such as surface roughness, porosity, protrusions, or shrinkage may occur, requiring further post-processing or finishing operations.

[0007] This invention proposes a method and apparatus for ultrasonic vibration-assisted superplastic forming of titanium alloys. It utilizes an ultrasonic vibration mechanism to generate ultrasonic vibrations that are transmitted to the titanium alloy sheet through a high-temperature steel column. This enhances the high-temperature plastic deformation capacity of the titanium alloy, improves the friction between the sheet and the mold, thereby increasing the part's mold fit and reducing defects. This method and apparatus have advantages such as wide applicability and significantly improved forming performance. Summary of the Invention

[0008] To address the aforementioned issues, this invention incorporates ultrasonic vibration-assisted forming during the superplastic forming process of titanium alloys. Under the combined action of high-pressure gas and ultrasonic vibration, the high-temperature yield strength and flow stress of the titanium alloy sheet, as heated to superplasticity, are reduced, shortening the superplastic forming cycle. Applying ultrasonic vibration during the pressure holding forming process improves its mold-fitting properties, thereby enhancing the contour accuracy of the formed parts and the yield rate of finished products.

[0009] To achieve the above objectives, the present invention adopts the following specific technical solution: a method for ultrasonic vibration-assisted superplastic forming of titanium alloys, comprising the following steps:

[0010] Step S1: Select the ultrasonic vibration frequency generated by the ultrasonic generator according to the different types, thicknesses, sizes and forming shapes of titanium alloy plates, adjust the ultrasonic vibration amplitude, and generate a suitable ultrasonic vibration mode by changing the transducer or amplitude transformer; adjust the heating temperature, heating time and output pressure of the gas source system of the heating furnace.

[0011] Step S2: Place the titanium alloy sheet to be processed into the forming mold of the heating furnace, turn on the gas source system to extract the air from the forming mold and fill it with argon gas.

[0012] Step S3: Control the heating temperature of the electric furnace to heat the titanium alloy sheet to the superplastic temperature and hold it at that temperature;

[0013] Step S4: The gas source system introduces pressurized argon gas into the forming mold, and at the same time turns on the ultrasonic generator. The high-temperature steel column is driven by the amplitude transformer to output a stable cyclic ultrasonic load and transfer it to the forming mold. Ultrasonic vibration is applied to the titanium alloy sheet to be processed until the titanium alloy sheet is completely attached to the forming mold. The mold is then kept warm for a period of time to ensure the dimensional accuracy of the formed part.

[0014] Step S5: Cool down the heating furnace, open the furnace door, remove the formed titanium alloy parts, and clean the forming mold.

[0015] Furthermore, in step S1, the frequency range of the ultrasonic vibration generated by the ultrasonic generator is 18~60KHz, the amplitude range of the ultrasonic vibration is 8~20um, and the vibration mode used in the ultrasonic vibration during the superplastic forming process is longitudinal vibration.

[0016] Furthermore, in step S2, the vacuum degree inside the forming mold during the extraction of air is ≤2×10⁻⁶. -4 The pressure is MPa, and the purity of the argon gas used is 99.99%, which is intended to prevent oxidation of the molded parts.

[0017] Furthermore, in step S3, the heating temperature and holding time are determined according to the temperature and holding time required for the forming process of the selected titanium alloy. Different titanium alloy plates require different temperatures and holding times.

[0018] Furthermore, in step S4, when the titanium alloy sheet is heated to a superplastic state, the gas source system introduces argon gas into the forming mold to blow-form the titanium alloy sheet. The pressure of the introduced argon gas is 2MPa~4MPa.

[0019] Furthermore, in step S4, the forming time of the titanium alloy sheet under the action of argon gas is 1.5~2h. Under the frequency and amplitude of ultrasonic vibration described in step S1, the forming time of the titanium alloy sheet decreases as the frequency and amplitude of ultrasonic vibration increase.

[0020] Furthermore, in step 5, ultrasonic vibration is continued to be applied during the cooling process of the heating device to improve the precision of the formed part.

[0021] An ultrasonic vibration-assisted superplastic forming device for titanium alloys includes: a heating furnace, a forming mold, a forming gas path, and an ultrasonic vibration mechanism;

[0022] The heating furnace is a heating device for titanium alloy plates; the heating furnace is equipped with a heat insulation layer and a heating block.

[0023] The forming mold is located inside the heating furnace, and a heat insulation layer and heating blocks are arranged around the forming mold; the forming mold includes an upper mold and a lower mold, and the cavities of the upper mold and the lower mold are arranged opposite to each other;

[0024] The output end of the forming air passage is connected to the lower mold; the input end of the forming air passage is connected to an external air source system.

[0025] The ultrasonic vibration mechanism is used to generate and transmit ultrasonic vibrations; it includes an ultrasonic generator, a transducer, an amplitude transformer, and a high-temperature steel column. The ultrasonic generator is connected to the transducer via a wire. The transducer and the amplitude transformer are located outside the heating furnace. The transducer is threadedly connected to the amplitude transformer via a stud. One end of the high-temperature steel column is threadedly connected to the amplitude transformer via a stud, and the other end is threadedly connected to the upper mold via a stud.

[0026] Furthermore, it also includes a water cooling system; the water cooling system is installed inside the high-temperature steel column.

[0027] Furthermore, the external gas source system is used to extract air from inside the forming mold and to introduce argon gas into the forming mold.

[0028] The present invention can achieve the following technical effects:

[0029] This invention incorporates ultrasonic vibration-assisted forming during the superplastic forming process of titanium alloys. Under the combined action of high-pressure argon gas and ultrasonic vibration, the high-temperature yield strength and flow stress of the titanium alloy sheet, which has reached superplasticity after heating, are reduced, shortening the superplastic forming cycle. Applying ultrasonic vibration during the forming process improves its mold adhesion, thereby increasing the contour accuracy of the formed parts and the yield of finished products.

[0030] This invention, by adjusting the amplitude, frequency, and vibration mode of ultrasonic vibration, is applicable to titanium alloy plates of different grades, and has wide applicability. Attached Figure Description

[0031] Figure 1 This is a flowchart of an ultrasonic vibration-assisted superplastic forming method for titanium alloys;

[0032] Figure 2 This is a schematic diagram of the ultrasonic vibration-assisted titanium alloy superplastic forming device (initial state).

[0033] Figure 3 This is a schematic diagram of an ultrasonic vibration-assisted titanium alloy superplastic forming device (forming state).

[0034] Figure 4 The graph shows the change in forming air pressure with the amplitude of ultrasonic vibration.

[0035] The attached figures are labeled as follows:

[0036] 1. Transducer, 2. Amplitude bar, 3. Water cooling system, 4. High-temperature steel column, 5. Insulation layer, 6. Heating block, 7. Upper mold, 8. Lower mold, 9. Titanium alloy sheet, 10. Forming air passage, 11. Ultrasonic generator. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0038] refer to Figure 1-4 A method for ultrasonic vibration-assisted superplastic forming of titanium alloys includes the following steps:

[0039] Step S1: Select the ultrasonic vibration frequency generated by the ultrasonic generator according to the different types, thicknesses, sizes and forming shapes of titanium alloy plates, adjust the ultrasonic vibration amplitude, and generate a suitable ultrasonic vibration mode by changing the transducer or amplitude transformer; adjust the heating temperature, heating time and output pressure of the gas source system of the heating furnace.

[0040] Step S2: Place the titanium alloy sheet into the forming mold of the heating furnace, turn on the gas source system to extract the air from the forming mold and fill it with argon gas.

[0041] Step S3: Control the heating temperature of the electric furnace to heat the titanium alloy sheet to the superplastic temperature and hold it at that temperature;

[0042] Step S4: The gas source system introduces pressurized argon gas into the forming mold, and at the same time turns on the ultrasonic generator. The high-temperature steel column is driven by the amplitude transformer to output a stable cyclic ultrasonic load and transfer it to the forming mold. Ultrasonic vibration is applied to the titanium alloy sheet to be processed until the titanium alloy sheet is completely attached to the forming mold. The mold is then kept warm for a period of time to ensure the dimensional accuracy of the formed part.

[0043] Step S5: Cool down the heating furnace, open the furnace door, remove the formed titanium alloy parts, and clean the forming mold.

[0044] Furthermore, in step S1, the frequency range of the ultrasonic vibration generated by the ultrasonic generator is 18~60KHz, the amplitude range of the ultrasonic vibration is 8~20um, and the vibration mode used in the ultrasonic vibration during the superplastic forming process is longitudinal vibration.

[0045] Furthermore, in step S2, the vacuum degree inside the forming mold when the air is extracted is ≤2×10⁻⁶. -4 The pressure is MPa, and the purity of the argon gas used is 99.99%, which is intended to prevent oxidation of the molded parts.

[0046] Furthermore, in step S3, the heating temperature and holding time are determined according to the temperature and holding time required for the forming process of the selected titanium alloy. Different titanium alloy plates require different temperatures and holding times.

[0047] Furthermore, in step S4, when the titanium alloy sheet is heated to a superplastic state, the gas source system introduces argon gas into the forming mold to blow-form the titanium alloy sheet. The pressure of the introduced argon gas is 2MPa~4MPa.

[0048] Furthermore, in step S4, the forming time of the titanium alloy sheet under the action of argon gas is 1.5~2h. Under the frequency and amplitude of ultrasonic vibration in step S1, the forming time of the titanium alloy sheet decreases as the frequency and amplitude of ultrasonic vibration increase.

[0049] Furthermore, in step 5, ultrasonic vibration is continued to be applied during the cooling process of the heating device to improve the precision of the formed part.

[0050] An ultrasonic vibration-assisted superplastic forming apparatus for titanium alloys, applied in the aforementioned ultrasonic vibration-assisted superplastic forming method for titanium alloys; comprising: a heating furnace, a forming mold, a forming gas path, and an ultrasonic vibration mechanism;

[0051] A heating furnace is a device used to heat titanium alloy sheets to superplastic temperatures. It is shaped like a cuboid, with an internal insulation layer and heating blocks, and an external furnace door and temperature controller to adjust the heating temperature and time.

[0052] The forming mold is located inside the heating furnace, and a heat insulation layer and heating blocks are arranged around the forming mold; the forming mold includes an upper mold and a lower mold, and the cavities of the upper mold and the lower mold are arranged opposite to each other;

[0053] The output end of the forming gas path is connected to the lower mold; the input end of the forming gas path is connected to an external gas source system; the gas source system extracts air from inside the forming mold and inputs argon gas into the forming mold through the forming gas path.

[0054] An ultrasonic vibration mechanism is used to generate and transmit ultrasonic vibrations; it includes an ultrasonic generator, a transducer, an amplitude transformer, and a high-temperature steel column. The ultrasonic generator is connected to the transducer via wires. The transducer and amplitude transformer are located outside the heating furnace. The transducer is connected to the amplitude transformer via studs and threads. One end of the high-temperature steel column is connected to the amplitude transformer via studs and threads, and the other end is connected to the upper mold via studs and threads.

[0055] The ultrasonic generator generates and modulates electrical signals and transmits them to the transducer. The transducer converts the electrical signals into mechanical vibrations and transmits the mechanical vibrations to the amplitude transformer. The amplitude transformer amplifies the mechanical vibrations and transmits them to the high-temperature steel column. The high-temperature steel column transmits the ultrasonic vibrations to the forming mold and applies ultrasonic vibrations to the titanium alloy sheet.

[0056] Furthermore, it also includes a water cooling system; the water cooling system is installed inside the high-temperature steel column to prevent the high temperature from affecting the ultrasonic vibration effect.

[0057] Furthermore, the external gas supply system is a device used to control the pressure and flow rate of the forming gas. It consists of a gas source, gas passage, valves, pressure gauges, flow meters, etc. The gas supply system is connected to the lower mold through the forming gas passage, and can introduce high-pressure argon gas into the mold to blow-form the titanium alloy sheet. The gas supply system can also extract air from the mold and fill it with argon gas to prevent the titanium alloy sheet from oxidizing at high temperatures.

[0058] Example 1

[0059] The initial structure of the ultrasonic vibration-assisted titanium alloy superplastic forming device is shown in the attached figure. Figure 2 As shown, this example uses titanium alloy sphere forming as an example, and includes the following steps:

[0060] Step 1: Select titanium alloy sheet; In this embodiment, TC3 titanium alloy sheet is selected, with a thickness of 2mm, a length of 60mm, and a width of 40mm; the forming temperature is 920℃; the ultrasonic vibration frequency is 18KHz and the amplitude is 8um; the vibration mode used in the ultrasonic vibration during the superplastic forming process is longitudinal vibration.

[0061] Step 2: Place the titanium alloy sheet between the upper and lower molds of the forming mold, place the forming mold into the heating furnace, extract the air from the forming mold through the forming gas path and fill it with argon gas.

[0062] Step 3: Start the heating furnace, and stop heating when the temperature reaches 920℃ and maintain the temperature.

[0063] Step 4: Pressurized argon gas is introduced into the forming mold by the gas supply system. Simultaneously, the ultrasonic generator is activated, driving a high-temperature steel column via an amplitude transformer to output a stable cyclic ultrasonic load, which is then transferred to the forming mold. Ultrasonic vibration is applied to the titanium alloy sheet to be processed until it completely adheres to the forming mold. The mold is then held at this temperature for 30 minutes to ensure the dimensional accuracy of the formed part. A schematic diagram of the ultrasonic vibration-assisted superplastic forming device for titanium alloys in its forming state is shown below. Figure 3 ;

[0064] Step 5: After the heating furnace cools down to 200℃, turn off the ultrasonic generator and stop the ultrasonic vibration. After the temperature drops to room temperature, open the furnace door, take out the formed titanium alloy parts, and clean the mold.

[0065] In the forming process of Example 1, ultrasonic vibration with a frequency of 18KHz and an amplitude of 8µm is applied to the titanium alloy to improve the high-temperature plastic deformation ability of the titanium alloy and improve the friction between the sheet and the mold. The formed part has good contour accuracy. The forming time of the titanium alloy sheet is 2 hours, which significantly shortens the forming cycle of the part compared with the traditional method.

[0066] Example 2

[0067] The initial structure of the ultrasonic vibration-assisted titanium alloy superplastic forming device is shown in the attached figure. Figure 2 As shown, this example uses titanium alloy sphere forming as an example, and includes the following steps:

[0068] Step 1: Select titanium alloy sheet; In this embodiment, TC3 titanium alloy sheet is selected, with a thickness of 2mm, a length of 60mm, and a width of 40mm; the forming temperature is 920℃; the ultrasonic vibration frequency is 60KHz and the amplitude is 20um; the vibration mode used in the ultrasonic vibration during the superplastic forming process is longitudinal vibration.

[0069] Step 2: Place the titanium alloy sheet between the upper and lower molds of the forming mold, place the forming mold into the heating furnace, extract the air from the forming mold through the forming gas path and fill it with argon gas.

[0070] Step 3: Start the heating furnace, and stop heating when the temperature reaches 920℃ and maintain the temperature.

[0071] Step 4: Pressurized argon gas is introduced into the forming mold by the gas supply system. Simultaneously, the ultrasonic generator is activated, driving a high-temperature steel column via an amplitude transformer to output a stable cyclic ultrasonic load, which is then transferred to the forming mold. Ultrasonic vibration is applied to the titanium alloy sheet to be processed until it completely adheres to the forming mold. The mold is then held at this temperature for 30 minutes to ensure the dimensional accuracy of the formed part. A schematic diagram of the ultrasonic vibration-assisted superplastic forming device for titanium alloys in its forming state is shown below. Figure 3 ;

[0072] Step 5: After the heating furnace cools down to 200℃, turn off the ultrasonic generator and stop the ultrasonic vibration. After the temperature drops to room temperature, open the furnace door, take out the formed titanium alloy parts, and clean the mold.

[0073] In Example 2, ultrasonic vibration with a frequency of 60 kHz and an amplitude of 20 μm was applied to the titanium alloy during the forming process, which improved the high-temperature plastic deformation ability of the titanium alloy, improved the friction between the sheet and the mold, and the formed part had good contour accuracy. The forming time of the titanium alloy sheet was 1.5 h, which further shortened the forming time compared with Example 1.

[0074] Example 3

[0075] The initial structure of the ultrasonic vibration-assisted titanium alloy superplastic forming device is shown in the attached figure. Figure 2 As shown, this example uses titanium alloy sphere forming as an example, and includes the following steps:

[0076] Step 1: Select titanium alloy sheet; In this embodiment, TC3 titanium alloy sheet is selected, with a thickness of 2mm, a length of 60mm, and a width of 40mm; the forming temperature is 920℃; the ultrasonic vibration frequency is 20KHz, and the amplitude is 5um; the vibration mode used in the ultrasonic vibration during the superplastic forming process is longitudinal vibration.

[0077] Step 2: Place the titanium alloy sheet between the upper and lower molds of the forming mold, place the forming mold into the heating furnace, extract the air from the forming mold through the forming gas path and fill it with argon gas.

[0078] Step 3: Start the heating furnace, and stop heating when the temperature reaches 920℃ and maintain the temperature.

[0079] Step 4: Pressurized argon gas is introduced into the forming mold by the gas supply system. Simultaneously, the ultrasonic generator is activated, driving a high-temperature steel column via an amplitude transformer to output a stable cyclic ultrasonic load, which is then transferred to the forming mold. Ultrasonic vibration is applied to the titanium alloy sheet to be processed until it completely adheres to the forming mold. The mold is then held at this temperature for 30 minutes to ensure the dimensional accuracy of the formed part. A schematic diagram of the ultrasonic vibration-assisted superplastic forming device for titanium alloys in its forming state is shown below. Figure 3 ;

[0080] Step 5: After the heating furnace cools down to 200℃, turn off the ultrasonic generator and stop the ultrasonic vibration. After the temperature drops to room temperature, open the furnace door, take out the formed titanium alloy parts, and clean the mold.

[0081] In Example 3, ultrasonic vibration with a frequency of 20 kHz and an amplitude of 5 μm was applied to the titanium alloy during the forming process. The wall thickness distribution of the formed part was relatively uneven, the surface quality was poor, and some defects such as pores and cracks led to the finished parts being unqualified. This shows that the amplitude of ultrasonic vibration has a significant impact on the performance and quality of superplastic forming of titanium alloys. Within a reasonable range, the larger the amplitude, the better the forming effect.

[0082] Method Mechanism

[0083] On a macroscopic level: Applying ultrasonic vibration during the superplastic forming process of titanium alloys improves the friction between the titanium alloy sheet and the mold, and achieves a uniform strain distribution in the sheet during gas expansion forming, resulting in more uniform wall thickness of the finished parts; it also improves the mold fit of the parts and reduces the occurrence of defects in the parts.

[0084] At the microscopic level: After ultrasonic vibration energy is input, the activation energy inside the material increases, thus continuously reducing the dynamic deformation resistance of the material; during the heating process, as the aging temperature increases, the martensite α′ decomposes into fine needle-like α+β mixture, and the application of ultrasonic vibration helps to promote the increase of grain size, decrease the aspect ratio, reduce grain boundaries, reduce the resistance to dislocation movement, and decrease the tensile strength; at the same time, during plastic deformation, the orientation difference between needle-like grains and between grains and grain boundaries is small, the deformation coordination and uniformity are better, and the elongation of the material is improved.

[0085] Compared with conventional superplastic forming, this invention can further improve the forming performance and forming quality of titanium alloy sheets through ultrasonic vibration, while also reducing the forming temperature and forming time of titanium alloy sheets.

[0086] In superplastic forming, ultrasonic vibration reduces the yield strength and flow stress of titanium alloy sheets, thereby lowering the pressure of the forming gas source required for forming. When the ultrasonic frequency is constant, the required forming gas pressure decreases as the amplitude increases, such as... Figure 4 As shown.

[0087] The shaping air pressure is represented by the dependent variable y, and the ultrasonic amplitude is represented by the independent variable x. The data curve can be fitted to the expression using the Origin software:

[0088]

[0089] The range of the independent variable x is 8~20um.

[0090] By adjusting the temperature of the heating furnace, the pressure of the gas source system, and the amplitude, frequency, and vibration mode of the ultrasonic vibration, this device can be applied to the superplastic forming of parts of different shapes, sheet materials, sizes, and thicknesses, making it widely applicable; it also reduces mold requirements and improves the part qualification rate.

[0091] In the description of this specification, the references to "one embodiment," "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0092] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0093] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for ultrasonic vibration-assisted superplastic forming of titanium alloys, characterized in that, Includes the following steps: Step S1: Select the ultrasonic vibration frequency generated by the ultrasonic generator according to the different types, thicknesses, sizes and forming shapes of titanium alloy plates, adjust the ultrasonic vibration amplitude, and generate a suitable ultrasonic vibration mode by changing the transducer or amplitude transformer; adjust the heating temperature, heating time and output pressure of the gas source system of the heating furnace. Step S2: Place the titanium alloy sheet to be processed into the forming mold of the heating furnace, turn on the gas source system to extract the air from the forming mold and fill it with argon gas. Step S3: Control the heating temperature of the electric furnace to heat the titanium alloy sheet to the superplastic temperature and hold it at that temperature; Step S4: The gas source system introduces pressurized argon gas into the forming mold, and at the same time turns on the ultrasonic generator. The high-temperature steel column is driven by the amplitude transformer to output a stable cyclic ultrasonic load and transfer it to the forming mold. Ultrasonic vibration is applied to the titanium alloy sheet to be processed until the titanium alloy sheet is completely attached to the forming mold. The mold is then kept warm for a period of time to ensure the dimensional accuracy of the formed part. Step S5: Cool down the heating furnace, open the furnace door, remove the formed titanium alloy parts, and clean the forming mold; In step S1, the ultrasonic generator generates ultrasonic vibrations with a frequency range of 18~60KHz and an amplitude range of 8~20um. The ultrasonic vibration mode used in the superplastic forming process is longitudinal vibration.

2. The method for ultrasonic vibration-assisted superplastic forming of titanium alloys according to claim 1, characterized in that, In step S2, the vacuum degree inside the forming mold during the extraction of air is ≤2×10⁻⁶. -4 The pressure is MPa, and the purity of the argon gas used is 99.99%, which is intended to prevent oxidation of the molded parts.

3. The method for ultrasonic vibration-assisted superplastic forming of titanium alloys according to claim 2, characterized in that, In step S3, the heating temperature and holding time are determined according to the temperature and holding time required for the forming process of the selected titanium alloy. Different titanium alloy plates require different temperatures and holding times.

4. The method for ultrasonic vibration-assisted superplastic forming of titanium alloys according to claim 3, characterized in that, In step S4, when the titanium alloy sheet is heated to a superplastic state, the gas source system introduces argon gas into the forming mold to blow-form the titanium alloy sheet. The pressure of the introduced argon gas is 2MPa~4MPa.

5. The method for ultrasonic vibration-assisted superplastic forming of titanium alloys according to claim 4, characterized in that, In step S4, the forming time of the titanium alloy sheet under the action of argon gas is 1.5~2h. Under the frequency and amplitude of ultrasonic vibration described in step S1, the forming time of the titanium alloy sheet decreases as the frequency and amplitude of ultrasonic vibration increase.

6. The method for ultrasonic vibration-assisted superplastic forming of titanium alloys according to claim 5, characterized in that, In step 5, ultrasonic vibration is continued to be applied during the cooling process of the heating device to improve the accuracy of the formed parts.

7. An ultrasonic vibration-assisted superplastic forming apparatus for titanium alloys, which is applied in the ultrasonic vibration-assisted superplastic forming method for titanium alloys according to any one of claims 1-6; characterized in that, include: Heating furnace, forming mold, forming air passage and ultrasonic vibration mechanism; The heating furnace is a heating device for titanium alloy plates; the heating furnace is equipped with a heat insulation layer and a heating block. The forming mold is located inside the heating furnace, and a heat insulation layer and heating blocks are arranged around the forming mold; the forming mold includes an upper mold and a lower mold, and the cavities of the upper mold and the lower mold are arranged opposite to each other; The output end of the forming air passage is connected to the lower mold; the input end of the forming air passage is connected to an external air source system. The ultrasonic vibration mechanism is used to generate and transmit ultrasonic vibrations; It includes an ultrasonic generator, a transducer, an amplitude transformer, and a high-temperature steel column. The ultrasonic generator is connected to the transducer via a wire. The transducer and the amplitude transformer are located outside the heating furnace. The transducer is threadedly connected to the amplitude transformer via a stud. One end of the high-temperature steel column is threadedly connected to the amplitude transformer via a stud, and the other end is threadedly connected to the upper mold via a stud.

8. The ultrasonic vibration-assisted titanium alloy superplastic forming device according to claim 7, characterized in that, It also includes a water cooling system; the water cooling system is installed inside the high-temperature steel column.

9. The ultrasonic vibration-assisted titanium alloy superplastic forming device according to claim 7, characterized in that, The external gas supply system is used to extract air from the mold and to introduce argon gas into the mold.

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