Gas channel setting method for superplastic forming / diffusion bonding of titanium alloy longitudinal and transverse high rib four-layer structure

Abstract

The application relates to a gas path setting method for superplastic forming / diffusion bonding of a titanium alloy longitudinal and transverse high rib four-layer structure member, and belongs to the technical field of aviation manufacturing. The forming method completes the superplastic forming and diffusion bonding of a longitudinal and transverse high rib four-layer integral complex structure part in two steps in one heat cycle, adopts optimal gas path and gas pressure setting parameters, and fully utilizes the excellent superplastic performance and diffusion performance of the titanium alloy; meanwhile, under the premise of ensuring the forming performance of the part, the forming quality of the part is ensured by reasonably setting the air passage and air passage intensity to prevent the material from collapsing in the hot state, and a technical foundation is laid for the application of the titanium alloy to complex structure parts of an aviation aircraft.

Description

Technical Field

[0001] This invention relates to a method for superplastic forming / diffusion connection gas path setting of a four-layer structure with longitudinal and transverse high ribs in titanium alloy, belonging to the field of aerospace manufacturing technology. Background Technology

[0002] Superplastic forming and superplastic forming / diffusion bonding processes are widely used in the forming of complex thin-walled titanium alloy components for aerospace applications, and are the main forming methods for titanium alloy parts in the aerospace field. However, traditional titanium alloy superplastic forming and superplastic forming / diffusion bonding processes are carried out at temperatures above 900℃. In the fabrication of multi-layer structural parts, due to the slow heating process and material softening under heat, the inner layer material softens and collapses under its own weight. During forming, the inner layer material needs to flow more due to collapse, which easily leads to defects such as shrinkage grooves on the part surface and excessive thinning of inner layer ribs. At the same time, as the structural design becomes more complex and the rib height gradually increases, the defects become more severe, failing to meet the forming requirements. Therefore, there is an urgent need for a gas path setting method for superplastic forming / diffusion bonding of four-layer structural parts with high longitudinal and transverse ribs in titanium alloys to ensure the forming quality and accuracy of multi-layer complex structural parts, and to achieve precise integrated manufacturing of complex structures. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for setting up a superplastic forming / diffusion connection gas path for a four-layer structure with high longitudinal and transverse ribs in titanium alloy. This method uses a superplastic forming / diffusion connection process to manufacture a four-layer structure with high longitudinal and transverse ribs in titanium alloy. This method can not only give full play to the superplastic properties of the material and manufacture high-quality parts, but also ensure the final forming quality of the parts and ensure that the various performance indicators of the parts after forming meet the requirements.

[0004] To solve the above problems, the specific technical solution of the present invention is as follows:

[0005] A method for setting up a superplastic forming / diffusion connection gas path for a four-layer structure with high longitudinal and transverse ribs in titanium alloy includes the following steps:

[0006] Step 1: The ventilation grooves of the first and second layers of the part, and the ventilation grooves of the third and fourth layers of the part are set on the same side of the part but staggered.

[0007] Step 2: The ventilation grooves of the second and third layers of the part are set on the other side of the part.

[0008] Step 3: Apply solder resist to the contact surface between the third and second layers of the part, following the unfolded template. When applying the solder resist, the width of the internal longitudinal and transverse ribs should be (2 × material thickness + 0.2) mm.

[0009] Step 4: When applying the anti-welding flux, leave a 5mm vent between the internal longitudinal and transverse ribs to facilitate uniform gas flow during vacuuming and gas-filling molding.

[0010] Step 5: Position the four layers of boards according to the ventilation grooves and shape, and then seal them with welding.

[0011] Step 6: During sealing, titanium tubes are welded to the ventilation grooves of the first and second layers of the plate, the third and fourth layers of the plate, the first and second layers of the plate, the third and fourth layers of the plate, and the second and third layers of the plate, respectively, and the ventilation grooves of the second and third layers of the plate are kept open.

[0012] Step 7: Place the four-layer sheet material after sealing and welding into the mold, and then place it together on the superplastic forming / diffusion bonding equipment platform.

[0013] Step 8: Heat the material to a higher temperature, and simultaneously introduce 0.5 bar of argon gas into the ventilation slots of the first and second layers of the board. The argon gas intensity introduced into the ventilation slots of the third and fourth layers of the board is [0.5 bar + × 9.8 / S], where G2 is the weight of the second layer of the board, G3 is the weight of the third layer of the board, and S is the surface area of ​​the second layer of the board / the third layer of the board. The ventilation slots of the second and third layers of the board are then evacuated.

[0014] Step 9: After the temperature rises to 780-790℃ and becomes uniform, argon gas is introduced into the ventilation grooves of the first and second layers of the sheet metal, as well as the ventilation grooves of the third and fourth layers of the sheet metal. The argon gas pressure is determined based on Formula 1 and the pressure required for diffusion bonding of the titanium alloy. Then, the superplastic forming of the first and fourth layers of the sheet metal and the diffusion bonding of the second and third layers of the sheet metal begin.

[0015]

[0016] in, σ represents the optimal strain rate at the forming temperature. A, B, C, and n are all anisotropic constants obtained from the calculation of the tensile stress-strain curve of the material at the forming temperature. σ is the rheological stress, and D is the ratio of the deformation activation energy to the forming temperature of the material at the forming temperature.

[0017] Step 10: After the superplastic forming process is completed, argon gas is introduced into the ventilation slots of the second and third layers of the sheet metal. The argon gas intensity is designed according to Formula 2. The holding time for each argon gas intensity is dynamically adjusted between 40 and 60 minutes based on the rib height. At this time, the ventilation slots of the first and second layers, as well as the ventilation slots of the third and fourth layers of the sheet metal, are evacuated for the diffusion bonding process.

[0018] P=[6+2×]bar……………………(2)

[0019] Where P is the argon gas intensity and n is the number of process steps.

[0020] Step 11: After the diffusion bonding process is completed, begin cooling. Simultaneously, introduce 0.3 bar of argon gas into the ventilation slots of the second and third layers of the substrate, and 0.2 bar of argon gas into the ventilation slots of the first and second layers, and the third and fourth layers. When the temperature drops to 300℃, remove the part and shape it.

[0021] The beneficial effects of this invention are:

[0022] This forming method completes the two-step process of superplastic forming and diffusion bonding of a complex four-layer integral structure part with high longitudinal and transverse ribs in one thermal cycle. It adopts the optimal air path and air pressure setting parameters to give full play to the excellent superplastic and diffusion properties of titanium alloy. At the same time, while ensuring the forming performance of the part, the method ensures that the material does not collapse under hot conditions by reasonably setting the air groove and air intensity, thus ensuring the forming quality of the part. This lays the technical foundation for the application of titanium alloy in complex structural parts of aerospace vehicles. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a four-layer structure with longitudinal and transverse high-strength ribs;

[0024] Figure 2 A schematic diagram of the ventilation groove 5 for the first layer of board 1 and the second layer of board 2;

[0025] Figure 3 A schematic diagram of the ventilation grooves 6 for the third layer board 3 and the fourth layer board 4;

[0026] Figure 4 A schematic diagram of the ventilation groove 7 for the second layer board 2 and the third layer board 3;

[0027] Figure 5 This is a schematic diagram of the overall layout of the ventilation ducts;

[0028] Figure 6 This is a schematic diagram of the unfolded template.

[0029] Among them, 1. First layer board, 2. Second layer board, 3. Third layer board, 4. Fourth layer board, 5. Ventilation grooves of the first and second layers board, 6. Ventilation grooves of the third and fourth layers board, 7. Ventilation grooves of the second and third layers board, 8. Contact surface between the third and second layers board, 9. Unfolded template, 10. Internal longitudinal and transverse ribs, 11. Ventilation openings reserved between internal longitudinal and transverse ribs. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. This embodiment is based on the technical solution of the invention and provides detailed implementation methods and specific implementation processes. However, the scope of protection of the present invention is not limited to the following implementation examples.

[0031] A method for setting up a superplastic forming / diffusion connection gas path for a four-layer structure with high longitudinal and transverse ribs in titanium alloy includes the following steps:

[0032] Step 1: The ventilation grooves 5 of the first and second layers of the first and second layers of the part, and the ventilation grooves 6 of the third and fourth layers of the third and fourth layers of the part are staggered on the same side of the part.

[0033] Step 2: The ventilation grooves 7 of the second and third layers of the part are set on the other side of the part.

[0034] Step 3: Apply solder resist to the contact surface 8 between the third layer plate 3 and the second layer plate 2, according to the unfolded template 9. When applying the solder resist, the width of the internal longitudinal and transverse ribs 10 should be (2 × material thickness + 0.2) mm.

[0035] Step 4: When applying the anti-welding flux, leave a 5mm vent 11 between the internal longitudinal and transverse ribs to facilitate uniform gas flow during vacuuming and gas-filling molding.

[0036] Step 5: Position the four layers of boards according to the ventilation grooves and shape, and then seal them with welding.

[0037] Step 6: During sealing, titanium tubes are welded to the ventilation grooves 5 of the first and second layers of the first and second layers of the first, third and fourth layers of the third layers of the second and third layers of the third layers of the second layers of the third layers of the third layers of the second layers of the third layers of the third layers of the second layers of the third layers of the third layers of the second layers of the third layers of the third layers of the second layers of the third layers of the third layers of the first ... second layers of the third layers of the first layers of the second layers of the third layers of the third layers of the second layers of the third layers of the first layers of the second layers of the third layers of the second layers of the third layers of the first layers of the second layers of the third layers of the second layers of the third layers of the first layers of the second layers of the third layers of the second layers of

[0038] Step 7: Place the four-layer sheet material after sealing and welding into the mold, and then place it together on the superplastic forming / diffusion bonding equipment platform.

[0039] Step 8: Heat the material to a higher temperature, and simultaneously introduce 0.5 bar of argon gas into the ventilation slots 5 of the first and second layers of the board. The argon gas intensity introduced into the ventilation slots 6 of the third and fourth layers of the board is [0.5 bar + G2 + G3 × 9.8 / S], where G2 is the gravity of the second layer 2, G3 is the gravity of the third layer 3, and S is the surface area of ​​the second layer 2 / the third layer 3. Vacuum the ventilation slots 7 of the second and third layers of the board.

[0040] Step 9: After the temperature rises to 780-790℃ and becomes uniform, argon gas is introduced into the ventilation grooves 5 of the first and second layers of the sheet metal, and the ventilation grooves 6 of the third and fourth layers of the sheet metal. The argon gas pressure is determined by a combination of Formula 1 and the pressure required for diffusion bonding of titanium alloy. Then, the superplastic forming of the first and fourth layers of the sheet metal and the diffusion bonding of the second and third layers of the sheet metal begin.

[0041]

[0042] in, σ represents the optimal strain rate at the forming temperature. A, B, C, and n are all anisotropic constants obtained from the calculation of the tensile stress-strain curve of the material at the forming temperature. σ is the rheological stress, and D is the ratio of the deformation activation energy to the forming temperature of the material at the forming temperature.

[0043] Step 10: After the superplastic forming process is completed, argon gas is introduced into the ventilation grooves 7 of the second and third layers of the sheet metal. The argon gas intensity is designed according to Formula 2. The holding time for each argon gas intensity is dynamically adjusted between 40 and 60 minutes based on the rib height. At this time, the ventilation grooves 5 of the first and second layers of the sheet metal, and the ventilation grooves 6 of the third and fourth layers of the sheet metal are evacuated for the diffusion bonding process.

[0044] P = [6 + 2 × n - 1] bar……………………2 where P is the argon gas intensity and n is the number of process steps.

[0045] Step 11: After the diffusion bonding process is completed, begin cooling. Simultaneously, introduce 0.3 bar argon gas into the ventilation slots 7 of the second and third layers of the substrate, and 0.2 bar argon gas into the ventilation slots 5 of the first and second layers, and the ventilation slots 6 of the third and fourth layers. When the temperature drops to 300℃, remove the part and shape it.

Claims

1. A method for setting a gas path in a titanium alloy longitudinal and transverse high rib four-layer structural member by superplastic forming / diffusion bonding, characterized by, It comprises the following steps: The first step: the first layer and the second layer of the first layer and the second layer of the part (1) and the second layer of the part (2) are distributed on the same side of the part, and the third layer and the fourth layer of the third layer and the fourth layer of the part (3) and the fourth layer of the part (4) are distributed on the same side of the part; The second step: the second layer and the third layer of the second layer and the third layer of the part (2) and the third layer of the part (3) are arranged on the other side of the part; The third step: the third layer and the second layer of the third layer and the second layer of the part (3) and the second layer of the part (2) are in contact with each other, and the third layer and the second layer of the part (3) and the second layer of the part (2) are in contact with each other according to the expansion template (9); The fourth step: when the flux is coated, the reserved vent (11) between the internal longitudinal and transverse ribs is reserved between the internal longitudinal and transverse ribs by 5mm; The fifth step: the four layers of the part are positioned according to the vent and the shape, and are sealed and welded; The sixth step: when the part is sealed and welded, the first layer and the second layer of the part (1) and the second layer of the part (2), the third layer and the fourth layer of the part (3) and the fourth layer of the part (4), the first layer and the second layer of the part (5), the third layer and the fourth layer of the part (6), the second layer and the third layer of the part (7) are respectively welded with titanium pipes, and the gas path is kept unobstructed; The seventh step: the four layers of the part after sealing and welding are put into the mold and are put together on the platform of the superplastic forming / diffusion bonding equipment; The eighth step: heating, while 0.5bar argon is introduced into the first layer and the second layer of the part (5), and argon is introduced into the third layer and the fourth layer of the part (6); the second layer and the third layer of the part (7) are vacuumized; The ninth step: after the temperature rises to 780-790℃ and the temperature is uniform, argon is introduced into the first layer and the second layer of the part (5) and the third layer and the fourth layer of the part (6); The tenth step: after the superplastic forming process is completed, argon is introduced into the second layer and the third layer of the part (7); at this time, the first layer and the second layer of the part (5) and the third layer and the fourth layer of the part (6) are vacuumized, and the diffusion bonding process is carried out; The eleventh step: after the diffusion bonding process is completed, the temperature is lowered, while 0.3bar argon is introduced into the second layer and the third layer of the part (7), and 0.2bar argon is introduced into the first layer and the second layer of the part (5) and the third layer and the fourth layer of the part (6); when the temperature drops to 300℃, the part is taken out, and the shape is made.

2. The method of claim 1, wherein the titanium alloy orthogrid four-layer structural member superplastic forming / diffusion bonding airway setting method is characterized by, In the third step, when the flux is coated, the width of the internal longitudinal and transverse rib part (10) is (2×material thickness+0.2)mm.

3. The method of claim 1 or 2, wherein the titanium alloy longitudinal high-aspect-ratio four-layer structure superplastic forming / diffusion bonding gas path setting method is characterized by, In the ninth step, the argon pressure is determined according to formula (1) and the pressure required for titanium alloy diffusion bonding, and the superplastic forming of the first layer and the fourth layer of the part and the diffusion bonding of the second layer and the third layer of the part are started; wherein, is the optimum strain rate at the forming temperature, A, B, C, n are constants calculated from the tensile stress-strain curve of the material at the forming temperature, σ is the flow stress, and D is the ratio of the deformation activation energy of the material at the forming temperature to the forming temperature.

4. The method of claim 1 or 2, wherein the titanium alloy longitudinal high-aspect-ratio four-layer structure superplastic forming / diffusion bonding gas path setting method is characterized by, In the eighth step, the argon strength is 0.5bar+(G2+G3)×9.8 / S; Wherein, G2 is the gravity of the second layer of plate (2), G3 is the gravity of the third layer of plate (3), and S is the surface area of the second layer of plate (2) / third layer of plate (3).

5. The method of claim 3, wherein the titanium alloy orthogrid four-layer structure superplastic forming / diffusion bonding air passage setting method is characterized by, In the eighth step, the argon gas intensity is 0.5 bar+(G2+G3)×9.8 / S; Wherein, G2 is the gravity of the second layer of plate (2), G3 is the gravity of the third layer of plate (3), and S is the surface area of the second layer of plate (2) / third layer of plate (3).

6. The method of claim 1 or 2 or 5, wherein the titanium alloy orthotropic four-layer structural member superplastic forming / diffusion bonding gas path setting method is characterized by, In the tenth step, the argon gas intensity is designed according to formula (2): P=6+2×(n-1) (2) Wherein, P is the argon gas intensity, and the unit is bar, and n is the step number; The argon gas intensity holding time of each step is dynamically adjusted between 40min-60min according to the rib height.

7. The method of claim 3, wherein the method is a method of gas passage arrangement for superplastic forming / diffusion bonding of a titanium alloy orthogrid four-layer structure, characterized by In the tenth step, the argon gas intensity is designed according to formula (2): P=6+2×(n-1) (2) Wherein, P is the argon gas intensity, and the unit is bar, and n is the step number; The argon gas intensity holding time of each step is dynamically adjusted between 40min-60min according to the rib height.

8. The method of claim 4, wherein the titanium alloy orthogrid four-layer structural member superplastic forming / diffusion bonding airway arrangement method is characterized by, In the tenth step, the argon gas intensity is designed according to formula (2): P=6+2×(n-1) (2) Wherein, P is the argon gas intensity, and the unit is bar, and n is the step number; The argon gas intensity holding time of each step is dynamically adjusted between 40min-60min according to the rib height.

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