A method for manufacturing a titanium alloy honeycomb sandwich panel by superplastic forming and diffusion bonding

Abstract

The application discloses a kind of titanium alloy honeycomb sandwich plate superplastic forming diffusion connection preparation method, belong to titanium alloy plate processing field, comprising the following steps: preparation panel, core plate and forming kit, carry out surface pretreatment and process air hole;In non diffusion connection area, coating resistance solder;Sequentially assembled and seal welded to form honeycomb sandwich preform;In hot press forming equipment, temperature is raised to diffusion connection temperature, mechanical pressure is applied and argon is filled into package to realize diffusion connection;Transferred to superplastic forming mould, temperature is raised to superplastic forming temperature and argon is filled to complete superplastic forming;Finally, with furnace cooling to obtain finished product.The forming kit can be selected stainless steel welding bag or titanium alloy package according to the thickness of panel.The method effectively solves the problems of mold cavity sealing difficulty and surface groove in traditional method, improves the forming quality, dimensional accuracy and material utilization rate of titanium alloy honeycomb sandwich plate, and is suitable for the field with high lightweight requirement such as aerospace.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy sheet processing, and in particular to a method for preparing titanium alloy honeycomb sandwich panels by superplastic forming diffusion bonding. Background Technology

[0002] Superplastic forming / diffusion bonding technology is an advanced metal processing technique widely used in the fabrication of hollow structures from metallic materials, such as titanium alloy honeycomb sandwich panels, corrugated three-layer structures, four-layer hollow structures, and lattice structures. This technology offers significant advantages, including high material utilization and short production cycles, and the resulting hollow structures possess complex geometries, high strength, and light weight. These characteristics make it an ideal choice for manufacturing components such as aircraft control wings and projectile casings in industries with urgent needs for lightweighting, such as aerospace and high-end weaponry.

[0003] Titanium alloy honeycomb sandwich panels are favored in numerous applications due to their advantages such as high specific strength, high specific stiffness, light weight, and integrated thermal and sound insulation. However, traditional methods for manufacturing titanium alloy honeycomb sandwich panels have some problems that urgently need to be solved. This method typically involves pressing titanium alloy sheets into a sealing groove of a superplastic forming mold under mechanical pressure to seal the mold cavity. Subsequently, the air inside the mold cavity is extracted and argon is injected to complete the diffusion bonding between the unformed titanium alloy honeycomb sandwich panels at the process temperature. During this process, it is necessary to extract air from the cavity and inject argon between the unformed titanium alloy honeycomb sandwich panels to complete the forming of the upper and lower panels and the honeycomb sandwich. However, traditional methods suffer from difficulties in sealing the mold cavity. This not only affects the vacuuming and inflation effects of the mold cavity but may also lead to the formation of planar grooves caused by the pulling of the honeycomb core cells during superplastic forming when the panel thickness of the titanium alloy honeycomb sandwich panel is less than 1 mm, thus affecting the surface quality and dimensional accuracy of the titanium alloy honeycomb sandwich panel. Therefore, solving the problems of difficult mold cavity sealing and easy formation of planar grooves in titanium alloy honeycomb sandwich panels is the key to superplastic forming / diffusion bonding in the preparation of titanium alloy honeycomb sandwich panels. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing titanium alloy honeycomb sandwich panels by superplastic forming diffusion bonding, in order to solve the problems of difficult mold cavity sealing and easy formation of planar grooves in titanium alloy honeycomb sandwich panels in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: a method for preparing a titanium alloy honeycomb sandwich panel by superplastic forming diffusion bonding, comprising the following steps:

[0006] Step S1: Prepare the panel, core board and molding kit. Mill air inlet holes at the mating positions of the panel, core board and molding kit. Grind and polish the panel and core board, pickle to remove the oxide layer, and clean and dry them.

[0007] Step S2: Apply solder resist to the non-diffusion bonding areas between the panel and the core board, and between the core boards;

[0008] Step S3: After placing the panel and core board in sequence, seal and weld them to form a honeycomb sandwich preform;

[0009] Step S4: Place the assembled honeycomb sandwich preform in a hot press forming equipment, heat it to the diffusion bonding process temperature of titanium alloy and keep it at that temperature, apply mechanical pressure, and fill the forming kit with argon gas to achieve diffusion bonding.

[0010] Step S5: After diffusion bonding is completed, the honeycomb sandwich preform is transferred to the superplastic forming mold, heated to the superplastic forming process temperature of titanium alloy and kept at that temperature, and argon gas is injected into the honeycomb sandwich preform to achieve superplastic forming.

[0011] Step S6: Cool the furnace to room temperature and remove the prepared titanium alloy honeycomb sandwich panel.

[0012] Furthermore, the forming kit is a stainless steel welded bag, which is formed by sealing two layers of stainless steel plates together. The length and width of the stainless steel welded bag are greater than the panel and the core plate.

[0013] Furthermore, the hot pressing forming equipment includes an upper hot pressing forming upper mold and a lower hot pressing forming lower mold, wherein the upper hot pressing forming upper mold and / or the lower hot pressing forming lower mold are flat molds or concave-convex molds.

[0014] Furthermore, when the upper die of the hot pressing forming equipment or the lower die of the hot pressing forming equipment is a concave die, the stainless steel welding bag is placed between the honeycomb sandwich preform and the concave die.

[0015] Furthermore, the forming kit is a titanium alloy sleeve, which consists of two cover plates of the same material and size as the panel and the core plate, and is welded to the upper and lower surfaces of the two panels. The titanium alloy sleeve undergoes the same drilling, grinding and pickling pretreatment as the panel and the core plate.

[0016] Furthermore, the cover plate, panel, and core plate are made of 0.3~1.5mm thick Ti65 titanium alloy sheet.

[0017] Furthermore, the hot pressing forming equipment directly adopts the superplastic forming mold.

[0018] Furthermore, the mechanical pressure applied by the hot pressing forming equipment is 25t.

[0019] Furthermore, argon gas is introduced into the molding kit to achieve diffusion connection, and the pressure is maintained at 0.01~0.1MPa / min until it reaches 2~3MPa for 2 hours.

[0020] Furthermore, the process involves filling the honeycomb sandwich preform with argon gas to achieve superplastic forming, and then loading it at 0.01~0.1MPa / min to 2~3MPa and holding the pressure until the panel completely fits the cavity of the superplastic forming mold or the inner cavity of the titanium alloy sheath.

[0021] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0022] This invention, in the diffusion bonding process of the layers of a titanium alloy honeycomb sandwich panel, differs from the traditional method of vacuuming and then filling the mold cavity. Instead, it employs a stainless steel welding bag or a similar titanium alloy cover plate for encapsulation. This effectively avoids argon leakage problems caused by difficulties in sealing the sealing groove during vacuuming and excessive deformation of the titanium alloy at the sealing groove due to increased gas pressure in the mold cavity during filling. This improves the welding rate between the layers and further ensures the strength of the component.

[0023] In the method of this invention, when preparing titanium alloy honeycomb sandwich panels using a titanium alloy cover plate, the cover plate is first superplastically formed to fully fit the mold cavity before being diffusely bonded to the titanium alloy honeycomb sandwich panel faceplate. This effectively avoids the appearance of grooves on the component surface, further ensuring the surface quality and dimensional accuracy of the titanium alloy honeycomb sandwich panel.

[0024] In the preparation of titanium alloy honeycomb sandwich panels using titanium alloy cover plates, the method of the present invention addresses the excessive thinning phenomenon that often occurs in large deformation areas such as rounded corners in traditional methods. Welding the cover plate to the panel can increase the wall thickness and eliminate the problem of thin weak areas caused by excessive thinning, thereby further ensuring the structural rigidity and integrity of the component.

[0025] The method of this invention can effectively avoid the material waste caused by severe indentation and damage to the surface of the sheet material during the processing in traditional methods, thereby improving the material utilization rate. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the titanium alloy honeycomb sandwich panel in Embodiment 1 of the present invention;

[0028] Figure 2This is a schematic diagram of the solder resist spraying in Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram of the honeycomb sandwich preform of Embodiment 1 of the present invention after being placed into the first hot pressing forming equipment;

[0030] Figure 4 This is a schematic diagram of the diffusion bonding process of the stainless steel welded bag in Embodiment 1 of the present invention.

[0031] Figure 5 This is a schematic diagram of the forming process using a superplastic forming mold in Embodiment 1 of the present invention. Figure 1 ;

[0032] Figure 6 This is a schematic diagram of the forming process using a superplastic forming mold in Embodiment 1 of the present invention. Figure 2 ;

[0033] Figure 7 This is a schematic diagram of the titanium alloy honeycomb sandwich panel in Embodiment 2 of the present invention;

[0034] Figure 8 This is a schematic diagram of the solder resist spraying in Embodiment 2 of the present invention;

[0035] Figure 9 This is a schematic diagram of the honeycomb sandwich preform of Embodiment 2 of the present invention after being placed into the second hot pressing forming equipment;

[0036] Figure 10 This is a schematic diagram of the diffusion bonding process of the stainless steel welded bag in Embodiment 2 of the present invention.

[0037] Figure 11 This is a schematic diagram of the forming process using a superplastic forming mold in Embodiment 2 of the present invention. Figure 1 ;

[0038] Figure 12 This is a schematic diagram of the forming process using a superplastic forming mold in Embodiment 2 of the present invention. Figure 2 ;

[0039] Figure 13 This is a schematic diagram of the structure of the encased titanium alloy honeycomb sandwich panel in Embodiment 3 of the present invention;

[0040] Figure 14 This is a schematic diagram of the solder resist spraying in Embodiment 3 of the present invention;

[0041] Figure 15 This is a schematic diagram illustrating the superplastic forming of the cover plate and the diffusion connection between the panel and the core plate, and between the core plates, in Embodiment 3 of the present invention. Figure 1 ;

[0042] Figure 16This is a schematic diagram illustrating the superplastic forming of the cover plate and the diffusion connection between the panel and the core plate, and between the core plates, in Embodiment 3 of the present invention. Figure 2 ;

[0043] Figure 17 This is a schematic diagram of the diffusion connection between the cover plate and the panel, and the superplastic forming process between the panel and the core plate in Embodiment 3 of the present invention.

[0044] In the figure: 1. Honeycomb sandwich preform; 101. First panel; 102. First core board; 103. Second core board; 104. Second panel; 105. Solder resist; 106. First cover plate; 107. Second cover plate; 2. First hot press forming upper mold; 3. Rectangular ring; 4. First hot press forming lower mold; 5. Stainless steel welding bag; 6. Superplastic forming mold; 7. Second hot press forming upper mold; 8. Second hot press forming lower mold. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] This invention provides a method for preparing a titanium alloy honeycomb sandwich panel using superplastic forming and diffusion bonding, comprising the following steps: designing the honeycomb unit cell size; selecting a stainless steel welding bag 5 or a titanium alloy sheath as the forming kit based on the thickness of the titanium alloy honeycomb sandwich panel and process requirements; and performing superplastic forming / diffusion bonding. The pre-welding preparation process involves: polishing the panel and core board with sandpaper, removing surface oxide scale by acid pickling, spraying solder resist 105 in the non-diffusion bonding area according to the honeycomb structure design, and sequentially placing the stainless steel welding bag 5 or a similar cover plate and each layer of the titanium alloy honeycomb sandwich panel and sealing them around the perimeter. Subsequently, the entire panel is heated to the process temperature using a hot-press forming device, and mechanical pressure is applied. The stainless steel welding bag 5 or the titanium alloy sheath is pressurized through an air inlet pipe welded before heating, achieving diffusion bonding between the titanium alloy honeycomb sandwich panels. After completing the diffusion bonding, the honeycomb sandwich preform 1 is inflated to prepare the titanium alloy honeycomb sandwich panel.

[0048] In one specific embodiment, the titanium alloy honeycomb sandwich panel is made of titanium alloy blank, the stainless steel welding bag 5 is made of two stainless steel plates welded together, and the titanium alloy cover is made of two cover plates of the same material as the panel and the core plate welded together.

[0049] In one specific embodiment, a stainless steel welding bag 5 or a similar titanium alloy cover plate is selected as the forming kit according to the panel thickness and process requirements of the titanium alloy honeycomb sandwich panel. Specifically, when the panel thickness is 0.3~1mm, a flat, groove-free similar titanium alloy sheet is selected as the cover plate; when the panel thickness is 1~5mm, a stainless steel welding bag 5 is selected.

[0050] In one specific embodiment, a titanium alloy honeycomb sandwich panel is prepared by superplastic forming / diffusion bonding using a stainless steel welding bag 5. The stainless steel welding bag 5 is prepared by sealing two layers of stainless steel plates, and the length and width of the stainless steel plates are greater than those of the panel and the honeycomb sandwich core panel.

[0051] In one specific embodiment, a titanium alloy honeycomb sandwich panel is prepared by superplastic forming / diffusion bonding with the same titanium alloy cover plate. Two plates with the same length and width as the panel and the honeycomb sandwich core plate are prepared as cover plates. The cover plates are subjected to the same sanding and pickling pretreatment as the panel and the honeycomb sandwich core plate to remove the oxide scale on the surface of the cover plates.

[0052] In one specific embodiment, when sequentially placing the stainless steel welding bag 5 and the layers of the titanium alloy honeycomb sandwich panel, different placement methods are selected according to the different structures of the upper and lower mold surfaces of the hot pressing forming equipment. Specifically, this includes: When both the upper and lower mold surfaces of the hot pressing forming equipment are flat, the stainless steel welding bag 5 and the layers of the titanium alloy honeycomb sandwich panel are placed sequentially from bottom to top. A rectangular ring 3 made of high-temperature mold steel is fitted around the outer side of each layer of the titanium alloy honeycomb sandwich panel. The height of the rectangular ring 3 is 15-10 mm greater than the honeycomb sandwich preform, the distance between the inner side of the rectangular ring 3 and the outer side of the honeycomb sandwich preform 1 is 5-15 mm, and the outer side of the rectangular ring 3 is less than or equal to the size of the stainless steel welding bag 5. When the upper mold surface of the hot pressing forming equipment is flat and the lower mold surface is a concave mold cavity, each layer of the titanium alloy honeycomb sandwich panel (honeycomb sandwich preform 1) is placed inside the concave mold cavity. The outer side of the honeycomb sandwich preform 1 is 5-15 mm away from the inner wall of the concave mold cavity, the height of the honeycomb sandwich preform 1 is 5-10 mm lower than the upper surface of the concave mold, and the stainless steel welding bag 5 is placed on the upper surface of the concave mold.

[0053] In one specific embodiment, when placing the same type of titanium alloy cover plate sleeve and titanium alloy honeycomb sandwich panel layers in sequence, the two cover plates are placed on the top and bottom sides of each layer of titanium alloy honeycomb sandwich panel, respectively, and the cover plates and each layer of titanium alloy honeycomb sandwich panel are sealed and welded around their perimeters.

[0054] In one specific embodiment, a titanium alloy honeycomb sandwich panel is prepared by superplastic forming / diffusion bonding using a stainless steel welding bag 5. During mechanical pressurization, heating, and gas filling, the temperature is raised to the titanium alloy diffusion bonding process temperature. Subsequently, mechanical pressure is applied and argon gas is filled into the stainless steel welding bag 5. The gas pressure is increased to 2~3MPa at 0.01~0.1MPa / min and then kept at the temperature for 2h to achieve diffusion bonding.

[0055] In one specific embodiment, when preparing a titanium alloy honeycomb sandwich panel using a stainless steel welding bag 5 for superplastic forming / diffusion bonding, after the diffusion bonding is completed, the honeycomb sandwich preform 1 is moved to the superplastic forming mold 6, heated to the titanium alloy superplastic forming temperature, and argon gas is injected into the space between the panels through the gas inlet pipe. The gas pressure is increased to 2~3MPa at 0.01~0.1MPa / min, and then the pressure is maintained until the panel completely fits the mold cavity. The panel is then cooled to room temperature, and the formed titanium alloy honeycomb sandwich panel is removed.

[0056] In one specific embodiment, a titanium alloy honeycomb sandwich panel with a cover plate is prepared by superplastic forming / diffusion bonding using the same titanium alloy cover plate. During mechanical pressurization, heating, and gas filling, the mold used is a superplastic forming mold 6 designed according to the dimensions of the titanium alloy honeycomb sandwich panel component. The temperature is raised to the titanium alloy diffusion bonding process temperature. Then, mechanical pressure is applied to the process supplementary surfaces of the cover plate and the honeycomb sandwich preform 1, and argon gas is filled between the cover plate and the panel. The gas pressure is loaded to 2~3MPa at 0.01~0.1MPa / min and then held at the temperature for 2h to achieve diffusion bonding.

[0057] In one specific embodiment, a titanium alloy honeycomb sandwich panel is prepared by superplastic forming / diffusion bonding using the same titanium alloy cover plate. After diffusion bonding is completed, the argon gas between the cover plate and the panel is evacuated to a vacuum, and argon gas is injected into the honeycomb sandwich preform 1 through the gas inlet pipe. The gas pressure is increased from 0.01~0.1MPa / min to 2~3MPa. The pressure is maintained until the panel is completely attached to the inner cavity of the cover plate for 2 hours to achieve diffusion bonding between the cover plate and the panel. After cooling to room temperature, the formed titanium alloy honeycomb sandwich panel with cover plate is taken out.

[0058] Example 1

[0059] Reference Figures 1 to 6 As shown, Embodiment 1 of the present invention provides a method for preparing a titanium alloy honeycomb sandwich panel by superplastic forming diffusion bonding. In this method, a Ti65 titanium alloy sheet with a thickness of 1.5 mm is selected as the face plate and core plate of the titanium alloy honeycomb sandwich panel. According to the face plate thickness and process requirements, a stainless steel welding bag 5 is selected for diffusion bonding between the sheets of the honeycomb sandwich preform 1. Simultaneously, the upper and lower surfaces of the first hot pressing forming equipment are both planar. The specific preparation method for a titanium alloy honeycomb sandwich panel with Ti65 titanium alloy sheet material includes the following steps:

[0060] Step S1, Material Pretreatment:

[0061] Prepare four 1.5mm thick Ti65 titanium alloy plates as face plates and core plates, and two stainless steel plates, each 15mm longer and wider than the titanium alloy plates and 2mm thick. The Ti65 titanium alloy plates include a first face plate 101, a first core plate 102, a second core plate 103, and a second face plate 104. The stainless steel plates are used to make the stainless steel welding bag 5 (forming kit). Mill 0.6mm deep air inlets at the mating positions of the face plates, core plates, and stainless steel plates. Grind and polish the face plates and core plates to remove surface oil, and use an acid pickling solution prepared with hydrofluoric acid, nitric acid, and water to remove the surface oxide layer. Finally, clean with anhydrous ethanol and dry.

[0062] Step S2, Spray solder resist 105:

[0063] Based on the design of the titanium alloy honeycomb sandwich panel, silicon nitride is used as solder resist 105 for spraying in the non-diffusion connection areas between the panel and the core board, and between the core boards.

[0064] Step S3: Assemble the boards:

[0065] Titanium alloy plates are placed sequentially from bottom to top, and the edges are sealed with welded metal. Two layers of stainless steel plates are aligned and then sealed with welded metal to form a stainless steel welded bag 5, and an air inlet pipe is welded on.

[0066] Step S4, Hot pressing and diffusion connection:

[0067] The assembled honeycomb sandwich preform 1 and stainless steel welding bag 5 are placed in a first hot pressing forming device, which includes an upper mold 2 and a lower mold 4. Both the upper mold 2 and the lower mold 4 are planar molds. A rectangular ring 3, made of high-temperature mold steel, is placed between the upper mold 2 and the lower mold 4. The ring 3 is 10 mm high and 10 mm away from the edge of the honeycomb sandwich preform 1. The temperature is raised to the diffusion bonding process temperature of Ti65 titanium alloy, held for 30 min, and then a mechanical pressure of 25 t is applied. Argon gas is then introduced into the stainless steel welding bag 5, and the pressure is increased from 0.01 MPa / min to 3 MPa and held for 2 h to complete the diffusion bonding between the layers of titanium alloy. During the diffusion bonding process, the layers of titanium alloy are kept under vacuum.

[0068] Step S5, Superplastic forming:

[0069] The preform 1 of the honeycomb sandwich structure with diffusion connection is transferred to the superplastic forming mold 6 and heated again to the superplastic forming process temperature of Ti65 titanium alloy. After holding at the temperature for 30 minutes, argon gas is introduced into the preform 1 of the honeycomb sandwich structure. The gas pressure is increased from 0.01 MPa / min to 3 MPa and the pressure is held until the panel completely fits the mold cavity, thus completing the superplastic forming.

[0070] Step S6, Cooling and Post-processing:

[0071] After cooling to room temperature in the furnace, the prepared titanium alloy honeycomb sandwich panel is removed. This titanium alloy honeycomb sandwich panel includes a first panel 101, a first core panel 102, a second core panel 103, and a second panel 104, as detailed below. Figure 1 As shown.

[0072] Example 2

[0073] Reference Figures 7 to 12 As shown, Embodiment 2 of the present invention provides a method for preparing a titanium alloy honeycomb sandwich panel by superplastic forming diffusion bonding. In this method, a Ti65 titanium alloy sheet with a thickness of 1.5 mm is selected as the face plate and core plate of the titanium alloy honeycomb sandwich panel. According to the face plate thickness and process requirements, a stainless steel welding bag 5 is selected for diffusion bonding between the sheets of the honeycomb sandwich preform 1. A second hot pressing forming device is used for hot pressing and diffusion bonding. The second hot pressing forming device includes a second hot pressing forming upper mold 7 and a second hot pressing forming lower mold 8. The surface of the second hot pressing forming upper mold 7 is planar, and the second hot pressing forming lower mold 8 is a concave mold with a concave mold cavity. For a titanium alloy honeycomb sandwich panel with Ti65 titanium alloy sheet material, the preparation method specifically includes the following steps:

[0074] Step S1, Material Pretreatment:

[0075] Prepare four 1.5mm thick Ti65 titanium alloy plates as face plates and core plates, and two 1.5mm thick stainless steel plates, each 15mm longer and wider than the face plates. The Ti65 titanium alloy plates include a first face plate 101, a first core plate 102, a second core plate 103, and a second face plate 104. Mill 0.6mm deep air inlets at the mating positions of the face plates, core plates, and stainless steel plates. Grind and polish the face plates and core plates to remove surface oil, and use an acid pickling solution prepared with hydrofluoric acid, nitric acid, and water to remove the surface oxide layer. Finally, clean with anhydrous ethanol and dry.

[0076] Step S2, Spray solder resist 105:

[0077] Based on the design of the titanium alloy honeycomb sandwich panel, silicon nitride is used as solder resist 105 for spraying in the non-diffusion connection areas between the panel and the core board, and between the core boards.

[0078] Step S3: Assemble the boards:

[0079] Titanium alloy plates are placed sequentially from bottom to top and sealed around the edges. Two layers of stainless steel plates are aligned and sealed to form a stainless steel weld bag 5, and an air inlet pipe is welded on. The honeycomb sandwich preform 1 is placed in the concave mold cavity of the lower mold 8 of the second hot pressing forming equipment, with the outer side 10mm away from the inner wall of the cavity and the height 5mm lower than the upper surface of the concave mold cavity. The stainless steel weld bag 5 is placed on the upper surface of the concave mold cavity.

[0080] Step S4, Hot pressing and diffusion connection:

[0081] The assembled mold, welding bag, and plates are placed in a hot pressing forming equipment. The temperature is raised to the diffusion bonding process temperature of Ti65 titanium alloy, held for 30 minutes, and then a mechanical pressure of 25t is applied. Argon gas is then introduced into the stainless steel welding bag 5, and the pressure is increased from 0.01MPa / min to 3MPa and held for 2 hours to complete the diffusion bonding between the layers of titanium alloy plates. During the diffusion bonding process, the layers of titanium alloy plates are kept under vacuum.

[0082] Step S5, Superplastic forming:

[0083] The preform 1 of the honeycomb sandwich structure with diffusion connection is transferred to the superplastic forming mold 6 and heated again to the superplastic forming process temperature of Ti65 titanium alloy. After holding at the temperature for 30 minutes, argon gas is introduced into the preform 1 of the honeycomb sandwich structure. The gas pressure is increased from 0.01 MPa / min to 3 MPa and the pressure is held until the panel completely fits the mold cavity, thus completing the superplastic forming.

[0084] Step S6, Cooling and Post-processing:

[0085] After cooling to room temperature in the furnace, the prepared titanium alloy honeycomb sandwich panel is removed. This titanium alloy honeycomb sandwich panel includes a first panel 101, a first core panel 102, a second core panel 103, and a second panel 104, as detailed below. Figure 7 As shown.

[0086] Example 3

[0087] Reference Figures 13 to 17 As shown, Embodiment 3 of the present invention provides a method for preparing a titanium alloy honeycomb sandwich panel by superplastic forming diffusion bonding. In this method, a Ti65 titanium alloy sheet with a thickness of 0.8 mm is selected as the face plate and core plate of the titanium alloy honeycomb sandwich panel. Based on the face plate thickness and process requirements, the same cover plates (first cover plate 106 and second cover plate 107) are selected for preparing the encased titanium alloy honeycomb sandwich panel. The mechanical pressing mold (hot pressing equipment) is a superplastic forming mold 6 designed according to the dimensions of the titanium alloy honeycomb sandwich panel. The preparation method for the encased titanium alloy honeycomb sandwich panel with Ti65 titanium alloy sheet material specifically includes the following steps:

[0088] Step S1, Material Pretreatment:

[0089] Prepare six 0.8mm thick Ti65 titanium alloy plates, two of which will serve as cover plates, and the rest as face plates and core plates. Specifically, these include a first cover plate 106, a first face plate 101, a first core plate 102, a second core plate 103, a second face plate 104, and a second cover plate 107. Mill 0.4mm deep air inlets at the mating positions of the cover plates, face plates, and core plates. Grind and polish all plates to remove surface oil, and use an acid pickling solution prepared with hydrofluoric acid, nitric acid, and water to remove the surface oxide layer. Finally, clean with anhydrous ethanol and dry.

[0090] Step S2, Spray solder resist 105:

[0091] Based on the design of the titanium alloy honeycomb sandwich panel, silicon nitride is used as solder resist 105 for spraying in the non-diffusion connection areas between the panel and the core board, and between the core boards.

[0092] Step S3: Assemble the boards:

[0093] Two cover plates are placed on the top and bottom sides of each layer of the titanium alloy honeycomb sandwich panel, respectively. The cover plates and each layer of the titanium alloy honeycomb sandwich panel are then sealed around their perimeter. After welding the air inlet pipe, the panel is placed in the superplastic forming mold 6.

[0094] Step S4, Hot pressing and diffusion connection:

[0095] The assembled honeycomb sandwich preform 1 is placed in the superplastic forming mold 6. The temperature is raised to the diffusion bonding process temperature of Ti65 titanium alloy, held for 30 min, and then a mechanical pressure of 25t is applied. Argon gas is then introduced between the cover plate and the panel, and the pressure is increased from 0.01MPa / min to 3MPa and held for 2 h to complete the diffusion bonding between the cover plate and the panel. During the diffusion bonding process, the titanium alloy panel and the core plate, and the core plates and the core plates are kept in a vacuum state.

[0096] Step S5, Superplastic forming:

[0097] After completing the diffusion connection, the argon gas between the cover plate and the panel is extracted, and argon gas is introduced between the panel and the core plate, and between the core plates. The gas pressure is increased from 0.01MPa / min to 3MPa, and the pressure is maintained for 2 hours after the panel is completely attached to the inner cavity of the cover plate to achieve superplastic forming.

[0098] Step S6, Cooling and Post-processing:

[0099] After cooling to room temperature in the furnace, the prepared encased titanium alloy honeycomb sandwich panel is removed. This encased titanium alloy honeycomb sandwich panel includes a first cover plate 106, a first face plate 101, a first core plate 102, a second core plate 103, a second face plate 104, and a second cover plate 107, as detailed below. Figure 13 As shown.

[0100] The above embodiments are all based on the technical solutions provided by the present invention. By optimizing the selection of forming kits, mold design and process parameters, the difficulties in sealing the mold cavity and the surface grooves in the traditional method are effectively solved, thereby improving the preparation quality and efficiency of titanium alloy honeycomb sandwich panels.

[0101] Compared with the prior art, the superplastic forming diffusion bonding preparation method for titanium alloy honeycomb sandwich panels provided in the above embodiments effectively overcomes the forming defects and surface grooves caused by poor mold cavity sealing during the traditional preparation process, significantly improving the forming consistency, dimensional accuracy and material utilization of titanium alloy honeycomb sandwich panels. It is particularly suitable for aerospace and other fields with high requirements for lightweighting and structural performance.

[0102] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0103] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a titanium alloy honeycomb sandwich panel by superplastic forming diffusion bonding, characterized in that, include: Step S1, Material Pretreatment: Prepare six Ti65 titanium alloy plates with a thickness of 0.8mm, two of which are used as cover plates and the rest as face plates and core plates. Specifically, the first cover plate (106), the first face plate (101), the first core plate (102), the second core plate (103), the second face plate (104), and the second cover plate (107) are milled with air inlets of 0.4mm depth at the relative mating positions of the cover plate, face plate, and core plate. All plates are ground and polished. Step S2, Spraying solder resist (105): According to the design of the titanium alloy honeycomb sandwich panel, silicon nitride is used as a solder resist (105) to spray in the non-diffusion connection area between the panel and the core board, and between the core boards; Step S3: Assemble the boards: Place the two cover plates on the top and bottom sides of each layer of the titanium alloy honeycomb sandwich panel respectively, and seal the cover plates and each layer of the titanium alloy honeycomb sandwich panel around the perimeter. After welding the air inlet pipe, place it in the superplastic forming mold (6). Step S4, Hot pressing and diffusion connection: The hot pressing forming equipment includes a hot pressing forming upper mold and a hot pressing forming lower mold. The hot pressing forming upper mold and / or the hot pressing forming lower mold are flat molds or concave and convex molds. The assembled honeycomb sandwich preform (1) is placed in the superplastic forming mold (6). First, the cover plate is superplastic formed and completely fits the mold cavity. Then, it is diffused connected with the titanium alloy honeycomb sandwich panel. The temperature is raised to the diffusion connection process temperature of Ti65 titanium alloy. After holding the temperature for 30 minutes, a mechanical pressure of 25t is applied, and argon gas is injected between the cover plate and the panel. The gas pressure is loaded to 3MPa at 0.01MPa / min and then held for 2 hours to complete the diffusion connection between the cover plate and the panel. During the diffusion connection process, the titanium alloy panel and the core plate, and the core plate and the core plate are evacuated to a vacuum state. Step S5, Superplastic forming: After completing the diffusion connection, the argon gas between the cover plate and the panel is extracted, and argon gas is introduced between the panel and the core plate, and between the core plates. The gas pressure is increased from 0.01MPa / min to 3MPa, and the pressure is maintained for 2 hours after the panel is completely attached to the inner cavity of the cover plate to achieve superplastic forming. Step S6, Cooling and Post-processing: After cooling to room temperature in the furnace, the prepared clad titanium alloy honeycomb sandwich panel is taken out. The clad titanium alloy honeycomb sandwich panel includes a first cover plate (106), a first panel (101), a first core plate (102), a second core plate (103), a second panel (104), and a second cover plate (107).

Images