Forming device and forming method for manufacturing TC4 titanium alloy material cavity type structural part through current-assisted hot air expansion mold

Abstract

The invention discloses a forming device and a forming method for manufacturing a TC4 titanium alloy material cavity type structural part through a current-assisted hot air expansion mold, belongs to the field of material processing engineering, and aims to solve the problems of long period, low efficiency, high labor intensity and low film pasting degree during processing of a TC4 titanium alloy component. A current-assisted hot air expansion and ultrasonic vibration device is innovatively introduced. And through the current heat effect, the heating efficiency can be improved, the current has unpopular potential in improving the plasticity of the material, and finally the forming efficiency and quality of the titanium alloy structural part are improved. The ultrasonic vibration device is used for finely controlling the oscillation airflow, so that the elongation, the thickness uniformity and the forming speed of the material are increased, and the forming of parts with extremely complex shapes is facilitated. The forming device and the forming method are mainly used for the TC4 titanium alloy material cavity type structural part.

Description

Technical Field

[0001] The present invention belongs to the field of materials processing engineering, and particularly relates to a forming device and a forming method for manufacturing a cavity structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die. Background Art

[0002] Nowadays, with the development of the times, modern industry is experiencing unprecedented rapid growth, and the demand for high-performance components in various industries is increasing day by day. Especially in high-tech fields such as aerospace and biomedicine, the demand for titanium alloy material components with complex structures has become extremely urgent. In terms of material properties, titanium alloy materials have outstanding performances in various fields due to many remarkable advantages, such as high strength, low density, excellent corrosion resistance and biocompatibility. However, there are great contradictions in the forming and manufacturing of titanium alloy materials. There are certain problems in manufacturing complex components by traditional manufacturing methods, such as high plasticity difficulty, high scrap rate, and easy damage to the original mechanical properties, such as defects like cracks. This has severely restricted the application of titanium alloy.

[0003] From the perspective of process development, traditional hot gas expansion processing, which adopts a thermal cycle method, can indeed improve the plasticity of titanium alloy to a certain extent and manufacture some preliminary parts with complex structures, but the problems are also very obvious, such as extremely low thermal efficiency, long forming cycle, and low film sticking degree. From the processing of complex parts, in the superplastic forming process of parts with extremely complex shapes, such as small-round-corner deep-cavity parts, problems such as insufficient corner die sticking or even cracking are likely to occur during the forming process. Therefore, based on this, in order to solve the problems of long cycle, low efficiency, high labor intensity, and low film sticking degree existing in the processing of TC4 titanium alloy components, a forming device and a forming method for manufacturing a cavity structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die are provided. Summary of the Invention

[0004] The present invention aims to solve the problems of long cycle, low efficiency, high labor intensity, and low film sticking degree existing in the processing of TC4 titanium alloy components, and further provides a forming device and a forming method for manufacturing a cavity structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die;

[0005] A forming device for manufacturing a cavity structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die. The forming device includes an experimental platform, a pressing device, a gas expansion die unit and a current heating unit. The pressing device is installed on the inner top of the experimental platform. The gas expansion die unit is arranged directly below the pressing device and is installed on the inner bottom of the experimental platform. The top of the gas expansion die unit is in close contact with the pressing end of the pressing device. The titanium alloy raw material plate is clamped in the gas expansion die unit, and a connecting electrode plate is fixedly connected to each end of the titanium alloy raw material plate. The connecting electrode plates extend to the outside of the gas expansion die unit. The positive connection end and the negative connection end of the current heating unit are respectively arranged on both sides of the gas expansion die unit, and both the positive connection end and the negative connection end of the current heating unit are clamped on the connecting electrode plates at both ends of the titanium alloy raw material plate;

[0006] The gas expansion die unit includes a positive expansion air pipe, a reverse expansion upper die, a positive expansion lower die and a reverse expansion air pipe. The reverse expansion upper die is arranged above the positive expansion lower die, and the top of the reverse expansion upper die is in close contact with the pressing end of the pressing device. The bottom of the reverse expansion upper die is processed with a reverse expansion cavity. The positive expansion lower die is installed on the inner bottom of the experimental platform. The top of the positive expansion lower die is processed with a positive expansion cavity, and the reverse expansion cavity and the positive expansion cavity are arranged corresponding to each other. A positive expansion air pipe is arranged in the reverse expansion upper die. The air inlet end of the positive expansion air pipe extends to the outside of the reverse expansion upper die and is connected to an external gas supply device. The air outlet end of the positive expansion air pipe is communicated with the reverse expansion cavity. An ultrasonic vibrator is connected in series on the positive expansion air pipe. A reverse expansion air pipe is arranged in the positive expansion lower die. The air inlet end of the reverse expansion air pipe extends to the outside of the positive expansion lower die and is connected to an external gas supply device. The air outlet end of the reverse expansion air pipe is communicated with the positive expansion cavity.

[0007] Further, the experimental platform includes a ceiling and a bottom plate. The ceiling and the bottom plate are arranged parallel to each other up and down, and are connected by multiple support columns. The pressing device is installed on the bottom surface of the ceiling, and the positive expansion lower die is installed on the top surface of the bottom plate;

[0008] Further, the reverse expansion upper die is made of nickel-based alloy, and the positive expansion lower die is made of ceramic;

[0009] Further, mica sheets are attached to the bottom of the reverse expansion upper die and the top of the positive expansion lower die. The reverse expansion upper die and the positive expansion lower die are in close contact with the titanium alloy raw material plate through the mica sheets;

[0010] Further, the current heating unit includes a current source and two copper electrodes. The two copper electrodes are respectively clamped on a connecting electrode plate. One of the two copper electrodes is connected to the positive pole of the current source through a wire, and the other copper electrode of the two copper electrodes is connected to the negative pole of the current source through a wire;

[0011] Furthermore, the current heating unit further includes a water circulation system, which includes a water tank, two circulation water pumps, and two water circulation pipelines. The two water circulation pipelines are connected to the water tank through the two circulation water pumps, and each water circulation pipeline is correspondingly arranged in cooperation with a copper electrode;

[0012] A forming method realized by a forming device for manufacturing a cavity structure part of TC4 titanium alloy material by current-assisted hot gas bulging die. The forming method is realized through the following steps;

[0013] Step 1: Obtain a titanium alloy raw material plate and connecting electrode plates through machining: Cut the titanium alloy raw material plate and the connecting electrode plates located at both ends of the titanium alloy raw material plate from the raw material plate according to the established design dimensions by numerical control wire cutting, and ensure that all plate bodies are rectangular structures;

[0014] Step 2: Perform surface treatment on the titanium alloy raw material plate and the connecting electrode plates: First, perform mechanical treatment on the surfaces of the titanium alloy raw material plate and the connecting electrode plates, and then perform chemical cleaning on the surfaces of the titanium alloy raw material plate and the connecting electrode plates after the mechanical treatment;

[0015] Step 3: Perform hot gas bulging forming on the titanium alloy raw material plate: Arrange the two connecting electrode plates that have undergone surface treatment on both sides of the titanium alloy raw material plate and fix the three plate bodies. Place the titanium alloy raw material plate between the reverse bulging upper die and the forward bulging lower die. At the same time, clamp each copper electrode in the current heating unit on a connecting electrode plate. Use current heating to heat the titanium alloy raw material plate to the temperature required for hot gas bulging forming. At the same time, apply appropriate pressure through the pressing device to ensure the stable positions of the reverse bulging upper die, the forward bulging lower die, and the titanium alloy raw material plate. Finally, introduce inert gas with appropriate pressure through the air pipe to perform hot gas bulging forming. During the bulging process, the reverse bulging upper die, the forward bulging lower die, and the titanium alloy raw material plate are always in contact with the mica sheet to maintain insulation and the stability of the plate. When performing bulging, first perform reverse bulging according to a certain pressure curve pattern. After completing the reverse bulging, then perform forward bulging according to a certain pressure curve pattern through the ultrasonic vibrator to obtain the workpiece with the final target shape;

[0016] Step 4: Perform final processing on the target shape workpiece obtained in Step 3: Take out the workpiece after hot gas bulging forming from the reverse bulging upper die and the forward bulging lower die, and use machining to polish and clean the outer surface of the workpiece to obtain the final titanium alloy cavity structure;

[0017] Furthermore, the specific methods for performing mechanical treatment and surface chemical cleaning on the surfaces of the connecting electrode plates and the titanium alloy raw material plate in Step 2 are as follows:

[0018] The titanium alloy raw material plate and the connecting electrode plate obtained after processing in Step 1 are polished with sandpaper. The sandpaper is used for polishing in sequence of 180#, 240#, 400#, 800#, 1200#, and 1500# until the surfaces of the titanium alloy raw material plate and the connecting electrode plate are smooth and flat.

[0019] The titanium alloy raw material plate and the connecting electrode plate after being polished with sandpaper are cleaned with 95% alcohol on the plate surface to remove surface oil stains and impurities, then rinsed with distilled water, and then placed in an acid pickling solution. The ratio of the acid solution is HF:HNO 3 :H 2 O = 1:6:13. After acid pickling, the upper and lower plates are fully rinsed with distilled water to ensure that the residual acid solution on the plate surface is completely rinsed off. Finally, the upper and lower plates are dried with a hair dryer.

[0020] Further, in Step 3, through the current heating unit, the temperature of the titanium alloy raw material plate is raised to 900°C. At this time, the current density in the current heating unit is set to 4.61 A / mm 2 , and this temperature is maintained for 30 minutes. Subsequently, a pressure of 2 MPa is applied through the pressing device 2, and at the same time, an inert gas is introduced through the gas pipe for hot gas bulging forming operation:

[0021] Further, when bulging in Step 3, first perform reverse bulging according to a certain pressure curve. The reverse bulging pressurization process route for introducing gas through the reverse bulging gas pipe is: slowly reach 0.5 mpa in 20 min, reach 0.7 mpa in 10 min, reach 0.9 mpa in 10 min, reach 1.2 mpa in 10 min, reach 1.4 mpa in 10 min, and complete reverse bulging forming under the pressure of 1.4 mpa. After the reverse bulging forming is completed, then perform forward bulging according to a certain pressure curve through the ultrasonic vibrator. The forward bulging pressurization process route for introducing gas through the forward bulging gas pipe is: slowly reach 0.1 mpa in 5 min, slowly reach 0.2 mpa in 4 min, slowly reach 0.3 mpa in 4 min, slowly reach 0.4 mpa in 4 min, slowly reach 0.5 mpa in 5 min, reach 0.6 mpa in 10 min, reach 0.7 mpa in 10 min, reach 0.8 mpa in 10 min, and complete forward bulging forming under the pressure of 0.8 mpa. The forward bulging pressurization process route relies on the ultrasonic vibrator to perform periodic loading and unloading of the pressure and ensure that the pressure rises steadily and oscillates step by step to complete the hot gas bulging process.

[0022] The beneficial effects of this application compared with the prior art:

[0023] A forming device and a forming method for manufacturing a cavity-shaped structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die provided by this application have obvious advantages in manufacturing the cavity-shaped structure part of TC4 titanium alloy material by using the independently designed current-assisted hot gas expansion forming device for TC4 titanium alloy. This application innovatively introduces current-assisted hot gas expansion and an ultrasonic vibration device. Through the current thermal effect, the heating efficiency can be improved, and the current has great potential in improving the plasticity of the material, ultimately improving the forming efficiency and quality of the titanium alloy structural part. Through the ultrasonic vibration device, the oscillating air flow is finely controlled, increasing the elongation, thickness uniformity and forming speed of the material, which helps to form parts with extremely complex shapes. In the die design, the upper and lower dies are prepared from different materials. The upper die is made of nickel-based alloy, and the lower die is made of ceramic. The research work on current-assisted hot forming is carried out, and a one-time high-precision and stable forming method is developed to solve the problems of long manufacturing cycle, low efficiency, high labor intensity and low film sticking degree in the manufacturing of TC4 alloy cavity-shaped structural parts. At the same time, a current-assisted hot forming process is established to improve the problem of excessive fillet thinning rate and fill the gap in the manufacturing process technology of current-assisted hot forming of thin-sheet TC4 titanium alloy.

[0024] This application aims at the many deficiencies existing in the traditional hot gas expansion forming technology, such as large energy consumption and significant workpiece springback problems. In view of this technical background, to effectively overcome the technical problems in the machining of complex structural parts of TC4 titanium alloy material, current is applied to the hot gas expansion forming process. The Joule heat effect of the current causes the material to heat up rapidly, and the electroplastic effect further reduces the deformation resistance of the material. The combined action of these two effects significantly improves the forming quality and efficiency of the TC4 titanium alloy structural part. The introduction of an oscillating air pressure loading device increases the elongation, thickness uniformity and forming speed of the material, which helps to form parts with extremely complex shapes and fully meets the strict requirements of high-end fields for high-performance parts. Brief Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the forming device for manufacturing a cavity-shaped structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die provided by this application;

[0026] Figure 2 It is a schematic diagram of the air pipe area in the forming device for manufacturing a cavity-shaped structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die provided by this application: Detailed Description of the Invention

[0027] Detailed Description of the Invention 1: Combine Figure 1 and Figure 2To describe this embodiment, in this embodiment, a forming device for manufacturing a cavity structure part of TC4 titanium alloy material by using a current-assisted hot gas expansion die is provided. The forming device includes an experimental platform 1, a pressing device 2, a gas expansion die unit, and a current heating unit. The pressing device 2 is installed on the inner top of the experimental platform 1. The gas expansion die unit is arranged directly below the pressing device 2 and is installed on the inner bottom of the experimental platform 1. The top of the gas expansion die unit is in close contact with the pressing end of the pressing device 2. The titanium alloy raw material plate 12 is clamped in the gas expansion die unit, and a connecting electrode plate 11 is fixedly connected to each end of the titanium alloy raw material plate 12. The connecting electrode plates 11 extend to the outside of the gas expansion die unit. The positive connection end and the negative connection end of the current heating unit are respectively arranged on both sides of the gas expansion die unit, and both the positive connection end and the negative connection end of the current heating unit are clamped on the connecting electrode plates 11 at both ends of the titanium alloy raw material plate 12;

[0028] The gas expansion die unit includes a positive expansion gas pipe 3, a reverse expansion upper die 4, a positive expansion lower die 5, and a reverse expansion gas pipe 6. The reverse expansion upper die 4 is arranged above the positive expansion lower die 5, and the top of the reverse expansion upper die 4 is in close contact with the pressing end of the pressing device 2. The bottom of the reverse expansion upper die 4 is processed with a reverse expansion cavity. The positive expansion lower die 5 is installed on the inner bottom of the experimental platform 1. The top of the positive expansion lower die 5 is processed with a positive expansion cavity, and the reverse expansion cavity and the positive expansion cavity are arranged corresponding to each other. The positive expansion gas pipe 3 is arranged in the reverse expansion upper die 4. The intake end of the positive expansion gas pipe 3 extends to the outside of the reverse expansion upper die 4 and is connected to an external gas supply device. The outlet end of the positive expansion gas pipe 3 is communicated with the reverse expansion cavity. An ultrasonic vibrator 9 is connected in series on the positive expansion gas pipe 3. The reverse expansion gas pipe 6 is arranged in the positive expansion lower die 5. The intake end of the reverse expansion gas pipe 6 extends to the outside of the positive expansion lower die 5 and is connected to an external gas supply device. The outlet end of the reverse expansion gas pipe 6 is communicated with the positive expansion cavity.

[0029] Specific embodiment two: In combination with Figure 1 and Figure 2 To describe this embodiment, the difference between this embodiment and the first specific embodiment is that the experimental platform 1 includes a ceiling and a bottom plate. The ceiling and the bottom plate are arranged parallel to each other up and down, and are connected by multiple support columns. The pressing device 2 is installed on the bottom surface of the ceiling, and the positive expansion lower die 5 is installed on the top surface of the bottom plate. Other components and connection methods are the same as those in the first specific embodiment.

[0030] Specific embodiment three: In combination with Figure 1 and Figure 2 To describe this embodiment, the difference between this embodiment and the second specific embodiment is that the reverse expansion upper die 4 is made of nickel-based alloy, and the positive expansion lower die 5 is made of ceramic. Other components and connection methods are the same as those in the second specific embodiment.

[0031] Specific embodiment four: In combination with Figure 1 and Figure 2Regarding this embodiment, the difference between this embodiment and the third specific embodiment is that mica sheets are attached to the bottom of the reverse bulging upper die 4 and the top of the forward bulging lower die 5, and the reverse bulging upper die 4 and the forward bulging lower die 5 are in close contact with the titanium alloy raw material plate 12 through the mica sheets. The other components and connection methods are the same as those in the third specific embodiment.

[0032] Specific embodiment five: Combining Figure 1 and Figure 2 Regarding this embodiment, the difference between this embodiment and the fourth specific embodiment is that the current heating unit includes a current source 7 and two copper electrodes 10. The two copper electrodes 10 are respectively clamped on a connecting electrode plate 11, and one of the two copper electrodes 10 is connected to the positive pole of the current source 7 through a wire, and the other copper electrode 10 of the two copper electrodes 10 is connected to the negative pole of the current source 7 through a wire. The other components and connection methods are the same as those in the fourth specific embodiment.

[0033] Specific embodiment six: Combining Figure 1 and Figure 2 Regarding this embodiment, the difference between this embodiment and the fifth specific embodiment is that the current heating unit further includes a water circulation system. The water circulation system includes a water tank, two circulation water pumps and two water circulation pipelines 8. The two water circulation pipelines 8 are communicated with the water tank through the two circulation water pumps, and each water circulation pipeline 8 is correspondingly arranged in cooperation with one copper electrode 10. The other components and connection methods are the same as those in the fifth specific embodiment.

[0034] Combined with Embodiment 1 to Embodiment 6, through the experimental platform 1, the pressing device 2, the ultrasonic vibrator 9, the water circulation system, the current source 7, the copper electrode 10, the positive bulging lower die 5 (ceramics), the reverse bulging upper die 4 (nickel-based alloy), the positive bulging air pipe 3 and the reverse bulging air pipe 6. The combined action of these components enables the smooth implementation of the current-assisted hot gas bulging forming technology. The experimental platform 1 provides a stable working surface for hot gas bulging forming; the pressing device 2 ensures that the pressure required during the hot gas bulging forming process can be applied, and generally a hydraulic loading device is selected; the ultrasonic vibrator 9, as an oscillating air pressure loading device, forms an oscillating air flow in the exhaust chamber, and then can provide oscillating air pressure for the superplastic forming equipment, which is beneficial to the superplastic forming process of complex parts, improves the product quality of the parts, and reduces the defective rate; the water circulation system ensures the stability of the copper electrode during the hot gas bulging forming process; the current source 7 provides the necessary current for the entire forming process; the copper electrode 10 is mainly responsible for connecting the composite material to be formed, ensuring that the composite material, the current source and the sheet form a complete circuit; the positive bulging lower die 5 is designed with an integral flat surface made of ceramic material, which can withstand greater pressure and assist in workpiece forming; the reverse bulging upper die 4 is designed with a locally hollowed-out nickel-based alloy material and has two key functions: one is to provide a continuous blank holding force during forming to ensure the stable position of the sheet and the die; the other is to determine the specific position of the hot gas bulging forming; the function of the pressurized air pipe is to inject inert gas at a certain pressure to make the sheet bulge.

[0035] Embodiment 7: Combined with Figure 1 and Figure 2 describe this embodiment. In this embodiment, a forming device for manufacturing a cavity-shaped structural part of TC4 titanium alloy material by current-assisted hot gas bulging die is provided. The forming method is realized through the following steps:

[0036] Step 1: Obtain the titanium alloy raw material plate 12 and the connecting electrode plate 11 through machining: Use numerical control wire cutting to cut the titanium alloy raw material plate 12 and the connecting electrode plates 11 located at both ends of the titanium alloy raw material plate 12 from the raw material plate according to the established design dimensions, and ensure that all plates are rectangular structures;

[0037] Step 2: Perform surface treatment on the titanium alloy raw material plate 12 and the connecting electrode plate 11: First, perform mechanical treatment on the surfaces of the titanium alloy raw material plate 12 and the connecting electrode plate 11, and then perform chemical cleaning on the surfaces of the titanium alloy raw material plate 12 and the connecting electrode plate 11 after mechanical treatment;

[0038] Step 3: Perform gas inflation forming on the titanium alloy raw material plate 12: Arrange two connected electrode plates 11 that have undergone surface treatment on both sides of the titanium alloy raw material plate 12 and fix the three plate bodies. Place the titanium alloy raw material plate 12 between the reverse inflation upper die 4 and the forward inflation lower die 5. At the same time, clamp each copper electrode 10 in the current heating unit onto a connected electrode plate 11. Use current heating to heat the titanium alloy raw material plate 12 to the temperature required for hot gas inflation forming. At the same time, apply an appropriate pressure through the pressing device 2 to ensure the stable positions of the reverse inflation upper die 4, the forward inflation lower die 5, and the titanium alloy raw material plate 12. Finally, introduce an inert gas with an appropriate pressure through a gas pipe to perform hot gas inflation forming. During the gas inflation process, the reverse inflation upper die 4, the forward inflation lower die 5, and the titanium alloy raw material plate 12 are always in contact with the mica sheet to maintain insulation and the stability of the sheet. When performing the bulging, first perform reverse bulging according to a certain pressure curve pattern. After completing the reverse bulging, then perform forward bulging according to a certain pressure curve pattern through the ultrasonic vibrator 9 to obtain the workpiece with the final target shape;

[0039] Step 4: Perform final processing on the target shape workpiece obtained in Step 3: Take out the workpiece after hot gas inflation forming from the reverse inflation upper die 4 and the forward inflation lower die 5, and polish and clean the outer surface of the workpiece by mechanical processing to obtain the final titanium alloy cavity structure.

[0040] Specific Embodiment VIII: Combining Figure 1 and Figure 2 to illustrate this embodiment. The difference between this embodiment and Specific Embodiment VII is that the specific methods for mechanical treatment and surface chemical cleaning of the connected electrode plate 11 and the titanium alloy raw material plate 12 in Step 2 are as follows:

[0041] Sandpaper the titanium alloy raw material plate 12 and the connected electrode plate 11 obtained after processing in Step 1. The sandpaper is used for sanding in sequence according to 180#, 240#, 400#, 800#, 1200#, and 1500# until the surfaces of the titanium alloy raw material plate 12 and the connected electrode plate 11 are smooth and flat;

[0042] Clean the surfaces of the titanium alloy raw material plate 12 and the connected electrode plate 11 after sanding with 95% alcohol to remove surface oil stains and impurities, then rinse with distilled water, and then place them in an acid pickling solution. The ratio of the acid solution is HF:HNO 3 :H 2 O = 1:6:13. After pickling, thoroughly rinse the upper and lower plates with distilled water to ensure that the residual acid solution on the plate surface is completely rinsed off. Finally, dry the surfaces of the upper and lower plates with a hair dryer. Other compositions and connection methods are the same as those in Specific Embodiment VII.

[0043] Specific Embodiment IX: Combining Figure 1 and Figure 2Describing this embodiment, the difference between this embodiment and the eighth specific embodiment is that in step 3, the temperature of the titanium alloy raw material plate 12 is raised to 900 °C through the current heating unit, and at this time, the current density in the current heating unit is set to 4.61 A / mm 2 , and this temperature is maintained for 30 minutes. Subsequently, a pressure of 2 MPa is applied through the pressing device 2, and at the same time, an inert gas is introduced through the gas pipe for hot gas bulging forming operation. Other compositions and connection methods are the same as those in the eighth specific embodiment.

[0044] Tenth specific embodiment: Combining Figure 1 and Figure 2 to describe this embodiment, the difference between this embodiment and the ninth specific embodiment is that during the bulging process in step 3, reverse bulging is first performed according to a certain pressure curve. The reverse bulging pressurization process route for introducing gas through the reverse bulging gas pipe 6 is as follows: slowly reach 0.5 mpa in 20 minutes, reach 0.7 mpa in 10 minutes, reach 0.9 mpa in 10 minutes, reach 1.2 mpa in 10 minutes, reach 1.4 mpa in 10 minutes, and complete the reverse bulging forming under the pressure of 1.4 mpa. After the reverse bulging forming is completed, then forward bulging is performed according to a certain pressure curve through the ultrasonic vibrator 9. The forward bulging pressurization process route for introducing gas through the forward bulging gas pipe 3 is as follows: slowly reach 0.1 mpa in 5 minutes, slowly reach 0.2 mpa in 4 minutes, slowly reach 0.3 mpa in 4 minutes, slowly reach 0.4 mpa in 4 minutes, slowly reach 0.5 mpa in 5 minutes, reach 0.6 mpa in 10 minutes, reach 0.7 mpa in 10 minutes, reach 0.8 mpa in 10 minutes, and complete the forward bulging forming under the pressure of 0.8 mpa. The forward bulging pressurization process route relies on the ultrasonic vibrator to perform periodic loading and unloading of the pressure and ensure that the pressure rises steadily in a step-by-step oscillating manner to complete the hot gas bulging process. Other compositions and connection methods are the same as those in the eighth specific embodiment.

[0045] Combined with the seventh to tenth specific embodiments, it shows that the forming method provided by this application innovatively introduces current-assisted hot gas bulging and ultrasonic vibration devices. Through the current thermal effect, the heating efficiency can be improved, and the current has great potential in improving the plasticity of materials, ultimately improving the forming efficiency and quality of titanium alloy structural parts. Through the ultrasonic vibration device, the oscillating air flow can be precisely controlled, increasing the elongation, thickness uniformity, and forming speed of the material, which helps to form parts with extremely complex shapes.

[0046] The present invention has been disclosed above with preferred embodiments. However, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or equivalents within the scope of the technical solution of the present invention by using the disclosed structure and technical content. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention. Specific embodiments:

[0048] Taking the preparation process of a cavity-structured part made of TC4 titanium alloy material as an example, the hot gas expansion process steps of the current-assisted hot gas expansion forming die independently designed based on the present invention are described. The specific implementation methods are as follows

[0049] Step 1: Cut the titanium alloy raw material plate 12 and the connecting electrode plates 11 at both ends of the titanium alloy raw material plate 12 from the TC4 titanium alloy sheet according to the established design dimensions by means of numerical control wire cutting, and ensure that all plates are rectangular structures;

[0050] Step 2: Polish the processed TC4 titanium alloy raw material plate and the TC4 connecting electrode plate with sandpaper to make the surface smooth and flat. The sandpaper is used in sequence of 180#, 240#, 400#, 800#, 1200#, 1500#. After polishing, clean the surface of the TC4 titanium alloy raw material plate with 95% alcohol to remove surface oil stains and impurities, then rinse with distilled water, and then put it into the pickling solution. The ratio of the acid solution is HF:HNO 3 :H 2 O = 1:6:13. After pickling, thoroughly rinse the upper and lower plates with distilled water to ensure that the residual acid solution on the composite material surface is completely rinsed off. Finally, dry the surfaces of the upper and lower plates with a hair dryer;

[0051] Step 3: Arrange the two TC4 connecting electrode plates obtained in Step 2, i.e., connecting electrode plate 11, on the TC4 titanium alloy raw material plate 12 and fix the three plates. Place the TC4 titanium alloy raw material plate 12 between the reverse bulging upper die 4 and the forward bulging lower die 5. At the same time, clamp each copper electrode 10 in the current heating unit onto a TC4 connecting electrode plate 11. Use current heating to raise the temperature of the TC4 titanium alloy raw material plate 12 to 900°C. At this time, the current density is set to 4.61 A / mm2, and maintain this temperature for 30 minutes. At the same time, apply a pressure of 2 MPa through the hydraulic pressing device to ensure the stable positions of the reverse bulging upper die 4, the forward bulging lower die 5, and the titanium alloy raw material plate 12. At the same time, introduce inert gas through the air pipe to perform the hot gas bulging forming operation. The gas bulging process is divided into reverse and forward bulging. First, perform reverse bulging, and then perform forward bulging. The reverse bulging pressurization process route for introducing gas through the reverse bulging air pipe 6 is as follows: slowly reach 0.5 mpa in 20 minutes, reach 0.7 mpa in 10 minutes, reach 0.9 mpa in 10 minutes, reach 1.2 mpa in 10 minutes, reach 1.4 mpa in 10 minutes, and complete the reverse bulging forming while maintaining a pressure of 1.4 mpa. After the reverse bulging forming is completed, then perform forward bulging through the ultrasonic vibrator 9 according to a certain pressure curve. The forward bulging pressurization process route for introducing gas through the forward bulging air pipe 3 is as follows: slowly reach 0.1 mpa in 5 minutes, slowly reach 0.2 mpa in 4 minutes, slowly reach 0.3 mpa in 4 minutes, slowly reach 0.4 mpa in 4 minutes, slowly reach 0.5 mpa in 5 minutes, reach 0.6 mpa in 10 minutes, reach 0.7 mpa in 10 minutes, reach 0.8 mpa in 10 minutes, and complete the forward bulging forming while maintaining a pressure of 0.8 mpa. The forward bulging pressurization process route relies on the ultrasonic vibrator to perform periodic loading and unloading of the pressure and ensure that the pressure rises steadily and oscillates step by step to complete the hot gas bulging process;

[0052] Step 4: Perform final machining on the target-shaped workpiece obtained in Step 3: Take out the workpiece after hot gas bulging forming from the reverse bulging upper die 4 and the forward bulging lower die 5, and polish and clean the surface of the workpiece by mechanical machining to obtain the final titanium alloy cavity structure.

[0053] Use the self-designed TC4 titanium alloy current-assisted hot gas bulging forming device of the present application to prepare cavity structure parts. The prepared products have good surface quality, regular forming appearance, good film sticking, the film sticking gap is not greater than 0.5 mm, the fillet thinning rate is less than 50%, and the grain size is not greater than 8 microns. The preparation cycle is short. Compared with traditional superplastic forming, the efficiency is increased by 70 - 80%, showing good application potential in the field of hot gas bulging forming of complex structure parts.

Claims

1. A forming device for manufacturing TC4 titanium alloy cavity structure parts using an electric current-assisted hot inflation die, characterized in that: The forming device comprises an experimental platform (1), a pressure device (2), an air-expanding mold unit and an electric current heating unit, wherein the pressure device (2) is installed on the inner top of the experimental platform (1), the air-expanding mold unit is arranged directly below the pressure device (2), and the air-expanding mold unit is installed on the inner bottom of the experimental platform (1), the top of the air-expanding mold unit is in close contact with the pressure end of the pressure device (2), the titanium alloy raw material plate (12) is clamped in the air-expanding mold unit, and the two ends of the titanium alloy raw material plate (12) are respectively fixed with a connecting electrode plate (11), and the connecting electrode plate (11) extends to the outside of the air-expanding mold unit, the positive electrode connecting end and the negative electrode connecting end of the electric current heating unit are respectively arranged on both sides of the air-expanding mold unit, and the positive electrode connecting end and the negative electrode connecting end of the electric current heating unit are both clamped on the connecting electrode plates (11) at both ends of the titanium alloy raw material plate (12); The gas expansion mold unit comprises a positive expansion tube (3), a reverse expansion upper mold (4), a positive expansion lower mold (5) and a reverse expansion tube (6), wherein the reverse expansion upper mold (4) is arranged above the positive expansion lower mold (5), and the top of the reverse expansion upper mold (4) is in close contact with the pressure end of the pressure applying device (2), the bottom of the reverse expansion upper mold (4) is processed with a reverse expansion cavity, the positive expansion lower mold (5) is installed on the inner bottom of the experimental platform (1), the top of the positive expansion lower mold (5) is processed with a positive expansion cavity, and the reverse expansion cavity is arranged corresponding to the positive expansion cavity, and the reverse expansion upper mold (4) is in close contact with the pressure applying end of the pressure applying device (2). A positive inflation tube (3) is provided in the mold (4), an air inlet end of the positive inflation tube (3) extends to the outside of the reverse inflation upper mold (4) and is connected to an external air supply device, an air outlet end of the positive inflation tube (3) is connected to the reverse inflation cavity, an ultrasonic vibrator (9) is connected in series to the positive inflation tube (3), a reverse inflation tube (6) is provided in the positive inflation lower mold (5), an air inlet end of the reverse inflation tube (6) extends to the outside of the positive inflation lower mold (5) and is connected to an external air supply device, and an air outlet end of the reverse inflation tube (6) is connected to the positive inflation cavity.

2. According to claim 1, a forming device for manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die, characterized in that: The experimental platform (1) comprises a ceiling and a bottom plate. The ceiling and the bottom plate are arranged parallel to each other and are connected via a plurality of supporting columns. A pressure device (2) is installed on the bottom surface of the ceiling, and a positive expansion lower mold (5) is installed on the top surface of the bottom plate.

3. The forming device for manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die according to claim 2 is characterized in that: The reverse expansion upper die (4) is made of nickel-based alloy, and the positive expansion lower die (5) is made of ceramic.

4. The forming device for manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die according to claim 3 is characterized in that: The bottom of the reverse expansion upper die (4) and the top of the positive expansion lower die (5) are both attached with mica sheets, and the reverse expansion upper die (4) and the positive expansion lower die (5) are both in close contact with the titanium alloy raw material plate (12) through the mica sheets.

5. The forming device for manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die according to claim 3 is characterized in that: The current heating unit comprises a current source (7) and two copper electrodes (10), the two copper electrodes (10) are respectively clamped on a connecting electrode plate (11), and one of the two copper electrodes (10) is connected to the positive electrode of the current source (7) through a wire, and the other of the two copper electrodes (10) is connected to the negative electrode of the current source (7) through a wire.

6. The forming device for manufacturing TC4 titanium alloy cavity structure parts by using current-assisted hot inflation die according to claim 1 is characterized in that: The electric current heating unit also includes a water circulation system, which includes a water tank, two circulating water pumps and two water circulation pipelines (8). The two water circulation pipelines (8) are connected to the water tank via the two circulating water pumps, and each water circulation pipeline (8) is arranged in correspondence with a copper electrode (10).

7. A forming method implemented by a forming device for manufacturing a cavity-shaped structural part made of TC4 titanium alloy material using a current-assisted hot inflation die according to any one of claims 1 to 6, characterized in that: The forming method is achieved by the following steps: Step 1: obtaining a titanium alloy raw material plate (12) and a connecting electrode plate (11) by mechanical processing: cutting the titanium alloy raw material plate (12) and the connecting electrode plates (11) located at both ends of the titanium alloy raw material plate (12) from the raw material plate according to a predetermined design size by using a CNC wire cutting method, and ensuring that all plates are of a rectangular structure; Step 2: Surface treatment of the titanium alloy raw material plate (12) and the connecting electrode plate (11): firstly mechanically treat the surfaces of the titanium alloy raw material plate (12) and the connecting electrode plate (11), and then chemically clean the surfaces of the titanium alloy raw material plate (12) and the connecting electrode plate (11) after the mechanical treatment; Step 3: Performing air bulging forming on the titanium alloy raw material plate (12): Arranging two surface-treated connecting electrode plates (11) on both sides of the titanium alloy raw material plate (12) and fixing the three plates, placing the titanium alloy raw material plate (12) between the reverse bulging upper die (4) and the positive bulging lower die (5), and clamping each copper electrode (10) in the current heating unit on a corresponding connecting electrode plate (11), heating the titanium alloy raw material plate (12) to the required temperature for hot air bulging by using current heating, and applying appropriate pressure by the pressure device (2) to ensure The positions of the reverse expansion upper die (4), the positive expansion lower die (5) and the titanium alloy raw material plate (12) are stable. Finally, an inert gas of appropriate pressure is introduced through the air pipe to perform hot air expansion. During the air expansion process, the reverse expansion upper die (4), the positive expansion lower die (5) and the titanium alloy raw material plate (12) are always in contact with the mica sheet to maintain insulation and stability of the plate. When the expansion is performed, the reverse expansion is first performed according to a certain regular pressure curve. After the reverse expansion is completed, the ultrasonic vibrator (9) is used to perform the forward expansion according to a certain regular pressure curve to obtain a workpiece with a final target shape. Step 4: Final processing is performed on the target shaped workpiece obtained in step 3: the workpiece formed by hot air bulging is taken out from the reverse bulging upper die (4) and the positive bulging lower die (5), and the surface of the workpiece is polished and cleaned by mechanical processing to obtain the final titanium alloy cavity structure.

8. The forming method of manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die according to claim 7 is characterized in that: The specific method of mechanically treating and chemically cleaning the surfaces of the connecting electrode plate (11) and the titanium alloy raw material plate (12) in step 2 is as follows: The titanium alloy raw material plate (12) and the connecting electrode plate (11) obtained after processing in step 1 are polished with sandpaper, and the sandpaper is polished in sequence according to 180#, 240#, 400#, 800#, 1200#, and 1500# until the surfaces of the titanium alloy raw material plate (12) and the connecting electrode plate (11) are smooth and flat; The titanium alloy raw material plate (12) and the connecting electrode plate (11) after sandpaper polishing are cleaned with 95% alcohol to remove surface oil and impurities, and then rinsed with distilled water, and then placed in a pickling solution, the ratio of the acid solution is HF:HNO3:H2O=1:6:

13. After pickling, the upper and lower plates are fully rinsed with distilled water to ensure that the residual acid solution on the surface of the plate is completely rinsed off, and finally the upper and lower plates are blown dry with a hair dryer.

9. The forming method of manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die according to claim 8 is characterized in that: In step 3, the temperature of the titanium alloy raw material plate (12) is raised to 900° C. by means of an electric current heating unit, and the current density in the electric current heating unit is set to 4.61 A / mm 2 , maintaining the temperature for 30 minutes, and then applying a pressure of 2 MPa through the pressure applying device 2, while introducing inert gas through the air pipe to perform hot air bulging operation.

10. The forming method of manufacturing TC4 titanium alloy cavity structure parts by using a current-assisted hot inflation die according to claim 9, characterized in that: When the bulging is performed in step 3, reverse bulging is first performed according to a certain regular pressure curve, and the reverse bulging pressurization process route of introducing gas through the reverse bulging tube (6) is: slowly reaching 0.5 MPa in 20 minutes, reaching 0.7 MPa in 10 minutes, reaching 0.9 MPa in 10 minutes, reaching 1.2 MPa in 10 minutes, reaching 1.4 MPa in 10 minutes, and completing the reverse bulging forming under the pressure of 1.4 MPa. After the reverse bulging forming is completed, the ultrasonic vibrator (9) is used to perform forward bulging according to a certain regular pressure curve, and the gas is introduced through the positive bulging tube (3). Positive expansion pressurization process route: slowly reach 0.1 MPa in 5 minutes, slowly reach 0.2 MPa in 4 minutes, slowly reach 0.3 MPa in 4 minutes, slowly reach 0.4 MPa in 4 minutes, slowly reach 0.5 MPa in 5 minutes, reach 0.6 MPa in 10 minutes, reach 0.7 MPa in 10 minutes, reach 0.8 MPa in 10 minutes, and maintain the pressure of 0.8 MPa to complete the positive expansion forming. The positive expansion pressurization process route relies on an ultrasonic vibrator to periodically increase and decrease the pressure and ensure that the pressure rises steadily and gradually in an oscillating manner to complete the hot air expansion process.

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