Method for processing hyperbolic l-shaped profiles of 5a90 aluminum lithium alloy

Abstract

The present application relates to a kind of 5A90 aluminum lithium alloy hyperbolic L profile parts processing method, belong to aviation sheet metal parts manufacturing technical field.The present application proposes a kind of hyperbolic L aluminum lithium alloy profile parts forming method, realizes the accurate manufacturing of 5A90 aluminum lithium alloy profile parts with L shape, hyperbolic, multiple sunken features.This processing method can also be used to manufacture a variety of specifications profiles, different thickness, different angle complex aluminum lithium alloy profile aviation parts manufacturing.This processing method solves the angle and appearance size out-of-tolerance caused by part rebound in the process of aluminum lithium alloy hyperbolic multiple specifications profile parts combination forming, solves the aluminum lithium alloy part forming difficulty and rebound problem from root.The tolerance of the appearance of the part manufactured according to this processing method in natural state is ≤0.5mm, the angle tolerance satisfies ≤2°, the sunken depth tolerance is 0~+0.3mm.

Description

Technical Field

[0001] The invention relates to a processing method for a 5A90 aluminum-lithium alloy hyperbolic L-profile part, and belongs to the technical field of aviation sheet metal part manufacturing. Background Art

[0002] An aircraft fuselage primarily consists of curved skins and a frame beam framework. Curved components are a key component of the skeletal structure, and their forming quality directly impacts the aircraft's assembly precision and overall aerodynamic shape, significantly impacting its service performance, manufacturing cycle, and cost. Aluminum-lithium alloys offer excellent properties such as high thermal stability, low density, high specific strength, and slow fatigue crack growth rate. Double-curved L-sections made of aluminum-lithium alloy are crucial truss components in the rear fuselage, and their forming accuracy directly impacts the aircraft's aerodynamic shape and flight performance. Double-curved L-sections with multiple sags are typically formed using stretch bending. This process is the primary forming method for large curved components due to its low springback and excellent part fit. Traditional stretch bending methods, based primarily on empirical analysis and testing, necessitate multiple passes to prevent component rejection due to oblique sags. This process can result in numerous scratches and abrasions, impacting surface quality, and requires reshaping to meet design drawing requirements. Various forming defects such as cracking, wrinkling and springback may also occur during the stretch-bending process of profiles. These defects are closely related to the selection of process parameters. It is difficult to accurately and efficiently formulate the stretch-bending process parameters by relying solely on experimental research and theoretical analysis methods. The application of finite element software to simulate the stretch-bending process can more accurately predict the deformation trend of the profile and the possible forming defects. It also has a certain degree of accuracy in calculating the springback amount. The numerical simulation technology is used to analyze the causes of cross-sectional distortion defects such as vertical edge tilt and horizontal edge collapse in the stretch-bending forming of L-shaped aluminum-lithium alloy cross-section L-shaped profiles. The cross-sectional distortion is effectively suppressed by optimizing the baffle gap and reducing the depth of the support surface of the stretch-bending die. Summary of the Invention

[0003] This invention addresses the need for forming technology for 5A90 aluminum-lithium alloy L-shaped, hyperbolic profile parts with sags. It proposes a forming method for these hyperbolic L-shaped aluminum-lithium alloy parts, enabling the precise manufacture of 5A90 aluminum-lithium alloy parts with L-shape, hyperbolic curvature, and multiple sags. This processing method can also be used to manufacture complex aluminum-lithium alloy profiles for aviation parts in various specifications, thicknesses, and angles. A typical 5A90 T3S XC111-25 hyperbolic L-shaped aluminum-lithium alloy part is used as an example.

[0004] The technical solutions of the present invention are as follows:

[0005] The processing method of 5A90 aluminum-lithium alloy double-curvature L-profile is as follows:

[0006] Step 1: Determine the blanking dimensions. The blanking dimensions include the outer arc length of the part model plus a 300mm process allowance at both ends. The material surface must be smooth and free of visible cracks, splits, scratches, delamination, non-metallic inclusions, bubbles, corrosion spots, and other surface defects.

[0007] Step 2: Punching and cutting. After measuring the calculated blanking size with a special measuring tool, mark the L-profile and use a universal punching die to punch and cut according to the marked position.

[0008] Step 3: Solution + Water Quenching. When all temperature sensors on the equipment reach the process requirement of 460°C ± 5°C, the parts are placed in the furnace. When loading, the parts should be placed in the effective heating zone and should not touch each other to ensure that the molten nitrate can flow freely. The quenching transfer time of the parts should not exceed 30 seconds. When the parts are removed from the nitrate tank, they should stay above the tank for 2-3 seconds to allow the molten nitrate to remain. During solution cooling, the parts are cooled in flowing cold water at 10-40°C for 2 minutes or more.

[0009] Step 4: Stretch-bending. The stretch-bending die is fixed to the stretch-bending machine platform through the positioning pin holes and the two fixing pins on the stretch-bending machine platform. The positions of the two fixing pins are adjusted to adapt to the two positioning pin holes of the stretch-bending die to ensure that the stretch-bending die and the stretch-bending machine are fixed well. The angle between the stretch-bending die and the workbench is adjusted. The L-shaped jaws are selected according to the cross-sectional shape of the L-profile. The two ends of the part are clamped in the jaws on both sides. The clamping amount at both ends is not less than 100mm. According to the stretch-bending process parameters after finite element simulation, the parameter values ​​are input and stretch-bending is performed. The L-profile is bent until it is completely fitted with the stretch-bending die.

[0010] Step 5: Punching and sinking. Align the bent semi-finished part with the part line on the trimming die, use a marker to mark the sinking position and the edge line of the part end, remove the part, and punch and sink according to the marked sinking position. Ensure that there is no excess material on the die surface and the operator's hands are off the die surface. Then, step on the press clutch device to complete the punching and sinking of the L-profile.

[0011] Step 6: Reshape the part. Place the knockout die on the platform, compare the L-shaped profile part after punching and sinking with the knockout die surface, and manually knock out the part based on the deviation between the profile part shape and the knockout die surface to ensure that the profile part is evenly stressed. Use a feeler gauge to verify the fit between the profile part and the knockout die surface, and manually knock out parts of the profile part while verifying until the profile part and the knockout die surface are fit. The maximum gap between the feeler gauge and the fit is 0.3mm.

[0012] Step 7: cutting the edge allowance of both ends of the part. The trimmed part is knocked out according to the edge line of the two ends of the part drawn by the trimming die. The edge allowance is cut according to the line, and the edge burr is filed to keep the edge of the cut part smooth and smooth.

[0013] The processing method comprises three parts of stretch bending forming, stamping forming and manual local forming.

[0014] The tooling comprises a set of stretch bending dies, a set of sinking dies and a set of trimming dies.

[0015] The stretch bending die is used for L-shaped section stretch bending forming. The L-shaped section is bent through the stretch bending die. After stretch bending forming, the material will have springback. The size of springback is obtained by finite element simulation. The conclusion is used to increase the springback angle on the tooling to reduce the springback.

[0016] The stretch bending die comprises a base plate, an upper die plate, positioning pin holes, lightening round holes and reference holes. The base plate and the upper die plate are made of A3 carbon structural steel. The entire base plate is in the shape of a fan structure. The positioning pin holes are symmetrically made with a central shaft of 2-φ65. The center distance of the positioning pin holes is 220mm. The center distance of each positioning pin hole from the bottom end of the die seat is 80mm. The positioning pin holes are used for positioning connection between the base plate and the positioning pile of the stretch bending machine.

[0017] The outer arc shape of the upper die plate is consistent with the shape of the part forming. The width of the upper die plate is 30mm more than the cross-sectional width of the part. The height of the upper die plate is 20mm more than the height of the part. The base plate and the upper die plate are connected by screws. The gap in the middle is equivalent to the thickness of the part +0.4mm. The purpose of the added 0.4mm gap is to facilitate the removal of the formed part, and to avoid scratches and scratches during the removal process. The lightening round holes are used to reduce the weight of the base plate. The diameter is generally not less than φ100. The lightening round holes penetrate the base plate and are evenly distributed on the base plate. The reference holes are two in number and have a diameter of φ10H7. They are milling references for numerical control machining and detection of the base plate and the upper die plate. The base plate is appropriately provided with a lifting ring M16 for lifting the stretch bending die.

[0018] The sinking die is used for sinking L-shaped section. The transition zone sinking in the sinking die is manufactured according to the size required by the drawing of the part. The sinking depth in the sinking die is 0.5mm deeper than the depth required by the drawing. The deepening depth is adjusted appropriately according to the thickness of the part material. The reason for deepening the sinking depth is that the aluminum-lithium alloy material has the characteristic of springback.

[0019] The lower mold mainly comprises an upper mold, a lower mold, a baffle and a top plate. The upper mold is made of Q235-AF carbon structural steel, with a material specification of 65mm, an outer dimension of 265x70x65, and a groove milled on the side of the top surface of the upper mold. The starting position of the groove is 12mm from the top surface, the length of the groove is 265mm, the width of the groove is 12.5mm, and the depth of the groove is 8mm. The upper mold is suspended at the throat of the punch through the groove, and the bottom surface of the upper mold is milled according to the sinking depth and the transition zone width of the part. The lower mold is made of Q235-AF carbon structural steel, with a material specification of 33mm, an outer dimension of 265x85x33, and a groove milled on the upper surface of the lower mold according to the sinking depth and the transition zone width of the part. A groove is opened upward in the middle of the lower bottom surface, with a size of 33x10.2x8, and the long edges of the bottom surface are chamfered by 2x45°. The baffle is made of Q235-AF carbon structural steel, with a material specification of 30mm, an outer dimension of 265x85x30, and a groove milled on the upper surface of the baffle according to the sinking depth and the transition zone width of the part. A groove is opened upward in the middle of the lower bottom surface, with a size of 30x10.2x8, and the long edges of the bottom surface are chamfered by 2x45°. The top plate is made of quenched 45 high-quality carbon structural steel, with a material specification of 2mm, an outer dimension of 260x63x2, and a groove milled on the upper surface of the top plate according to the sinking shape of the part. A groove is opened upward in the middle of the lower bottom surface, with a size of 2x10.2x8, and the long edges of the bottom surface are chamfered by 2x45°. The top plate is used to hold the part and prevent the part from sinking during the sinking forming. The lower mold, the baffle and the top plate are connected together through two bolts, which are clamped with the general mold base on the punch through the grooves.

[0020] The set of knock repair molds is used for manual repair of local shapes, and the knock repair molds are also used for checking the part shape, bending angle and sinking depth. The final parts are required to meet the part shape tolerance ≤0.5mm, the angle tolerance ≤2° and the sinking depth tolerance 0~+0.3mm according to the drawing requirements.

[0021] The knock repair mold mainly comprises a tire body, an outer block, screw holes and numerical control reference holes. The tire body tooling material is A3 carbon structural steel, with a long arc structure similar to the arc structure of the part. The outer corners of the four surfaces of the tire body are all rounded with R5, which prevents scratching the operator and the part. The upper surface of the tire body is used to draw the edge line of the part according to the edge of the part solid model by using a numerical control milling machine. The profile of the outer block is completely consistent with the outer surface of the part, and the top end is rounded with R2 to prevent the sharp point from scratching the part. The outer surface of the outer block is processed in the same way as the tire body to draw the edge line of the L-shaped stud of the part. There are seven screw holes for installing screws, which are used to connect the tire body and the outer block. There are two numerical control reference holes with a diameter of φ10H7, which are located on both sides of the outer block.

[0022] Beneficial effects of the present invention:

[0023] This method solves the problem of forming aluminum-lithium alloy hyperbolic parts of varying specifications and sizes. It also addresses the angular and dimensional deviations caused by springback during the combined forming of aluminum-lithium alloy parts with multiple specifications, fundamentally resolving the difficulties and springback issues in forming aluminum-lithium alloy parts. Parts manufactured using this method achieve a natural shape tolerance of ≤0.5 mm, an angle tolerance of ≤2°, and a sink depth tolerance of 0 to +0.3 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the stretch-bending die of the present invention.

[0025] Figure 2 It is a schematic cross-sectional view of the stretch-bending die of the present invention.

[0026] Figure 3 It is a schematic diagram of the sinking mold of the present invention.

[0027] Figure 4 It is the front view of the sunken mold of the present invention.

[0028] Figure 5 This is a schematic diagram of the mold repair process of the present invention.

[0029] Figure 6 It is a schematic cross-sectional view of the knocking and repairing mold of the present invention.

[0030] In the figure: 1 bottom plate; 2 upper template; 3 positioning pin hole; 4 lightening round hole; 5 reference hole; 6 upper die; 7 lower die; 8 baffle; 9 top plate; 10 carcass; 11 outer stopper; 12 screw hole; 13 CNC reference hole. DETAILED DESCRIPTION

[0031] Example 1:

[0032] According to the processing process of 5A90 aluminum-lithium alloy L-shaped hyperbolic profile parts with multiple depressions, a typical 5A90 T3S XC111-25 hyperbolic L-shaped aluminum-lithium alloy part is selected as an example.

[0033] Step 1: Determine the blanking dimensions. The blanking dimensions include the outer arc length of the part model plus a 300mm process allowance at both ends. The material surface must be smooth and free of visible cracks, splits, scratches, delamination, non-metallic inclusions, bubbles, corrosion spots, and other surface defects.

[0034] Step 2: Punching and cutting. After measuring the calculated blanking size with a special measuring tool, mark the L-profile and use a universal punching die to punch and cut according to the marked position.

[0035] Third step: solid solution + water quenching treatment. When all temperature sensors of the equipment reach the process required heating temperature of 460℃±5℃, the parts are put into the furnace. The parts should be placed in the effective heating area when they are loaded into the furnace. The parts should not contact each other to ensure that the molten nitrate salt can flow freely. The part transfer time during quenching should be no more than 30s. When the parts are taken out of the nitrate salt tank, they should stay above the tank for 2s-3s to allow the molten nitrate salt to remain. During solid solution cooling, the parts are cooled in flowing cold water at 10℃-40℃ for ≥2min.

[0036] Fourth step: stretch bending forming. The stretch bending die is fixed on the stretch bending machine platform through the two fixed pins of the positioning pin hole-3 and the two fixed pins on the platform. The positions of the two fixed pins are adjusted to adapt to the two positioning pin holes-3 of the stretch bending die to ensure that the stretch bending die is fixed on the stretch bending machine. The angle between the stretch bending die and the workbench is adjusted. According to the L-shaped section shape, an L-shaped jaw is selected. The two ends of the part are clamped in the two jaw ports respectively, and the clamping amount of the two ends is not less than 100mm. According to the stretch bending process parameters after finite element simulation, the parameter values are input, and the stretch bending forming is carried out. The L-shaped section is bent to completely match the stretch bending die.

[0037] Fifth step: stamping sinking forming. The stretch-bent semi-finished part is aligned with the part tread line on the knock-off die. The sinking position and the part end edge line are marked with a marker. The part is removed, and the stamping sinking forming is carried out according to the marked sinking position. After ensuring that there is no excess material on the die closing surface and the operator's hands are away from the die closing surface, the press clutch device is pressed down to realize the stamping sinking forming of the L-shaped section.

[0038] Sixth step: trimming the shape of the part. The knock-off die is placed on the platform. The L-shaped section part after stamping sinking is compared with the knock-off die surface. According to the deviation between the shape of the section part and the knock-off die surface, the part is manually knocked off and formed. The section part is uniformly stressed. The fit of the section part and the knock-off die surface is verified by using a feeler gauge. The local part of the section part is manually knocked off and formed while verifying. Until the section part and the knock-off die surface are fitted, the feeler gauge specification and the maximum gap of the fit are 0.3mm.

[0039] Seventh step: cutting the edge excess of both ends. The edge line of both ends of the part is marked according to the tread line of the knock-off die. The edge excess is cut according to the line. The edge burr is filed to make the edge of the part cut smooth and transition.

[0040] Example 2:

[0041] The processing method of the hyperbolic L-shaped section of 5A90 aluminum lithium alloy includes stretch bending forming, stamping forming, and manual local forming.

[0042] The tooling includes a set of stretch bending dies, a set of sinking dies, and a set of knock-off dies.

[0043] The draw bending die is used for L-shaped profile draw bending forming, and a kind of forming method is bent by draw bending die for L-shaped profile, and material will have springback after draw bending forming, the size of springback is obtained by finite element simulation simulation, and the conclusion is added to realize reducing springback.

[0044] The draw bending die comprises a bottom plate 1, an upper die plate 2, positioning pin holes 3, lightening round holes 4 and reference holes 5, wherein the materials of the bottom plate 1 and the upper die plate 2 are A3 carbon structural steel, the entire bottom plate 1 is in the shape of a fan-shaped structure, the positioning pin holes 3 are symmetrically made with a middle shaft, the hole center distance of the positioning pin holes 3 is 220mm, the hole center distance of each positioning pin hole 3 is 80mm from the bottom end of the die seat, and the positioning pin holes 3 are used for positioning connection between the bottom plate 1 and the positioning pile of the draw bending machine.

[0045] The outer arc shape of the upper die plate 2 is consistent with the shape of the part forming, the width of the upper die plate 2 is 30mm more than the cross-sectional width of the part, the height of the upper die plate 2 is 20mm more than the height of the part, the bottom plate 1 is connected with the upper die plate 2 by screws, the gap in the middle is equivalent to the thickness of the part +0.4mm, and the increased 0.4mm gap is convenient for taking out the part after forming, and avoids scratches and scratches in the process of taking out the part. The lightening round hole 4 is used to reduce the weight of the bottom plate 1, the diameter is generally not less than φ100, penetrates the bottom plate 1, the position is not limited, and is uniformly distributed on the bottom plate 1. The reference holes 5 are two in number, the diameter is φ10H7, and are milling reference for numerical control processing and detecting the bottom plate 1 and the upper die plate 2. The bottom plate 1 is provided with a lifting ring M16 at a proper position, and is used for lifting the draw bending die.

[0046] The draw bending die is used for L-shaped profile draw bending forming, and a kind of forming method is bent by draw bending die for L-shaped profile, and material will have springback after draw bending forming, the size of springback is obtained by finite element simulation simulation, and the conclusion is added to realize reducing springback.

[0047] The said sinking die mainly comprises four parts: upper die 6, lower die 7, baffle 8 and top plate 9. The upper die 6 is made of Q235-AF carbon structural steel, with a material specification of 65mm, an outer dimension of 265x70x65mm, and a groove milled on the side end of the top surface of the upper die 6 by numerical control. The starting position of the groove is 12mm away from the top surface end, the length of the groove is 265mm, the width of the groove is 12.5mm, and the depth of the groove is 8mm. The bottom surface of the upper die 6 is milled by numerical control according to the sinking depth and the transition zone width of the part. The lower die 7 is made of Q235-AF carbon structural steel, with a material specification of 33mm, and an outer dimension of 265x85x33mm. The upper surface of the lower die 7 is milled by numerical control according to the sinking depth and the transition zone width of the part. A groove is opened upward in the middle of the lower bottom surface of the lower die 7, with a size of 33x10.2x8mm, and the long edges of the bottom surface are chamfered by 2x45°. The baffle 8 is made of Q235-AF carbon structural steel, with a material specification of 30mm, and an outer dimension of 265x85x30mm. The upper surface of the baffle 8 is milled by numerical control according to the sinking depth and the transition zone width of the part. A groove is opened upward in the middle of the lower bottom surface of the baffle 8, with a size of 30x10.2x8mm, and the long edges of the bottom surface are chamfered by 2x45°. The top plate 9 is made of quenched 45 high-quality carbon structural steel, with a material specification of 2mm, and an outer dimension of 260x63x2mm. The upper surface of the top plate 9 is milled by numerical control according to the sinking shape of the part. A groove is opened upward in the middle of the lower bottom surface of the top plate 9, with a size of 2x10.2x8mm, and the long edges of the bottom surface are chamfered by 2x45°. The top plate 9 is used to hold the part and prevent it from sinking during sinking forming. The lower die 7, the baffle 8 and the top plate 9 are connected together by two bolts, which are clamped with the general die holder on the punch through the grooves.

[0048] The set of knock-dressing dies is used for manually dressing the local shape. The knock-dressing die is also used for inspecting the part shape, bending angle and sinking depth. The final part is required to meet the part shape tolerance of ≤0.5mm, the angle tolerance of ≤2°, and the sinking depth tolerance of 0~+0.3mm according to the drawing requirements.

[0049] The knocking and repairing mold is mainly composed of a carcass 10, an outer stopper 11, screw holes 12, and a CNC reference hole 13. The tooling material of the carcass 10 is A3 carbon structural steel, and it has a long arc-shaped structure, similar to the arc-shaped structure of the part. The outer corners of the four sides of the carcass 10 are all rounded R5. The purpose of the R5 rounded corners is to prevent scratches on operators and parts. The upper surface of the carcass 10 is marked with the edge line of the part according to the edge of the part's physical digital model using a CNC milling machine. The profile of the outer stopper 11 is completely consistent with the outer surface of the part, and the top is rounded R2 to prevent sharp points from bumping and damaging the part. The outer surface of the outer stopper 11 is marked with the L-shaped vertical rib edge line of the part using the same processing method as the carcass 10. There are 7 screw holes 12 for installing screws, which are used to connect the carcass 10 and the outer stopper 11. There are 2 CNC reference holes 13 with a diameter of φ10H7, which are located on both sides of the outer stopper 11.

Claims

The processing method of 1.5A90 aluminum-lithium alloy double-curvature L-shaped profile is characterized in that: Here are the steps: Step 1: Determine the blanking size; the blanking size includes the outer arc length of the part model + 300mm process allowance at both ends. The material surface should be smooth and no visible cracks, cracks, scratches, delamination, non-metallic inclusions, bubbles, corrosion spots or surface defects are allowed. Step 2: Punching and cutting: After measuring the calculated blanking size with a special measuring tool, mark the L-profile, and use a universal punching die to punch and cut according to the marked position; Step 3: Solution + water quenching treatment; when the temperature of all temperature sensors of the equipment reaches the temperature range of 460℃±5℃ required by the process, the parts are put into the furnace. When loading the furnace, the parts should be placed in the effective heating zone and should not touch each other to ensure that the molten nitrate can flow freely. The quenching transfer time of the parts should not exceed 30s. When the parts are taken out of the nitrate tank, they should stay above the tank for 2s-3s to allow the molten nitrate to remain. During solution cooling, the parts are cooled in flowing cold water at 10℃-40℃ for ≥2min. Step 4: stretch-bending forming; the stretch-bending die is fixed on the stretch-bending machine platform through the positioning pin hole (3) and the two fixing pins on the stretch-bending machine platform, the positions of the two fixing pins are adjusted to adapt to the two positioning pin holes (3) of the stretch-bending die, and the stretch-bending die and the stretch-bending machine are fixed well, and the angle between the stretch-bending die and the workbench is adjusted, and the L-shaped jaws are selected according to the cross-sectional shape of the L-profile, and the two ends of the part are clamped in the jaws on both sides respectively, and the clamping amount at both ends is not less than 100mm, and the various parameter values ​​are input according to the stretch-bending process parameters after finite element simulation, and stretch-bending forming is performed, and the L-profile is bent until it is completely fitted with the stretch-bending die; Step 5: Use the sinking die to perform the sinking forming; align the semi-finished part after stretching and bending with the part tire line on the knocking die, mark the sinking position and the edge line of the part end with a marker, remove the part, and perform the sinking forming according to the marked sinking position. Ensure that there is no excess material on the die surface and the operator's hands are off the die surface, then step on the clutch device of the press to achieve the stamping sinking forming of the L-profile; Step 6: Trim the part shape; Place the knockout die on the platform, compare the L-shaped profile part after punching and sinking with the knockout die surface, and manually knock out the part according to the deviation between the profile part shape and the knockout die surface to ensure that the profile part is evenly stressed. Use a feeler gauge to verify the fit between the profile part and the knockout die surface, and manually knock out parts of the profile part while verifying until the profile part and the knockout die surface are fit. The maximum gap between the feeler gauge and the fit is 0.3mm. Step 7: Cut the edge allowance at both ends; mark the edge lines of the trimmed parts at both ends according to the mold line; cut the edge allowance along the line, file the edge burrs, and keep the edge of the part smooth after cutting.

2. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 1, characterized in that: The processing method comprises three parts: stretch bending forming, stamping forming, and manual partial forming; The tooling includes: bending die, sinking die and knocking die; The stretch bending die is used for stretch bending of L-shaped profiles. A forming method in which the L-shaped profile is bent through the stretch bending die. After stretch bending, the material will rebound. The magnitude of the rebound is obtained through finite element simulation. Based on the conclusion, the rebound angle is increased on the tooling to reduce the rebound. The bending die comprises: a base plate (1), an upper die plate (2), a positioning pin hole (3), a lightening circular hole (4) and a reference hole (5); wherein the base plate (1) is fan-shaped, and the positioning pin holes (3) are symmetrically formed with a middle axis, and the center spacing of the positioning pin holes (3) is 220 mm. The positioning pin holes (3) are used to position and connect the base plate (1) with the positioning piles of the bending machine; The outer arc shape of the upper template (2) is consistent with the shape of the part being formed. The base plate (1) and the upper template (2) are connected with screws. The gap difference in the middle is equivalent to the thickness of the part material + 0.4 mm. The lightening circular hole (4) is used to reduce the weight of the base plate (1). The diameter is not less than φ100 and passes through the base plate (1). The position is not limited and is evenly distributed on the base plate (1); the number of reference holes (5) is 2; the base plate (1) is installed with an M16 lifting ring for lifting the bending die.

3. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 1 or 2, characterized in that: The sinking die mainly comprises four parts: an upper die (6), a lower die (7), a baffle (8), and a top plate (9); the upper die (6) is suspended at the throat of the punch press through a groove, and the bottom surface of the upper die (6) is CNC milled according to the sinking depth and transition zone width of the part; a groove is opened upwards in the middle position of the lower bottom surface of the lower die (7), and the long sides on both sides of the bottom surface are chamfered 2×45°; a groove is opened upwards in the middle position of the lower bottom surface of the baffle (8), and the long sides on both sides of the bottom surface are chamfered 2×45°; a groove is opened upwards in the middle position of the lower bottom surface of the top plate (9), and the long sides on both sides of the bottom surface are chamfered 2×45°. The function of the top plate (9) is to support the part and prevent the part from sinking during sinking forming; the lower die (7), the baffle (8) and the top plate (9) are connected together by two bolts and are clamped to the universal die base on the punch press through the groove.

4. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 1 or 2, characterized in that: The knocking and repairing mold mainly consists of a carcass (10), an outer stopper (11), a screw hole (12), and a numerical control reference hole (13); the carcass (10) has a long arc structure, which is similar to the arc structure of the part. The outer corners of the four sides of the carcass (10) are all rounded R5, and the function of the rounded R5 is to prevent scratching the operator and the part. The upper surface of the carcass (10) is marked with the part edge line according to the edge of the part entity digital model by using a numerical control milling machine; the profile of the outer stopper (11) is completely consistent with the outer surface of the part, and the top end is rounded R2, the purpose is to prevent the sharp point from knocking and damaging the part; the outer surface of the outer stopper (11) is marked with the L-shaped vertical rib edge line of the part in the same processing method as the carcass (10); the number of screw holes (12) is 7, which are used to install screws, and the screws are used to connect the carcass (10) and the outer stopper (11); the number of numerical control reference holes (13) is 2, with a diameter of φ10H7, and they are respectively located on both sides of the outer stopper (11).

5. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 3, characterized in that: The knocking and repairing mold mainly consists of a carcass (10), an outer stopper (11), a screw hole (12), and a numerical control reference hole (13); the carcass (10) has a long arc structure, which is similar to the arc structure of the part. The outer corners of the four sides of the carcass (10) are all rounded R5, and the function of the rounded R5 is to prevent scratching the operator and the part. The upper surface of the carcass (10) is marked with the part edge line according to the edge of the part entity digital model by using a numerical control milling machine; the profile of the outer stopper (11) is completely consistent with the outer surface of the part, and the top end is rounded R2, the purpose is to prevent the sharp point from knocking and damaging the part; the outer surface of the outer stopper (11) is marked with the L-shaped vertical rib edge line of the part in the same processing method as the carcass (10); the number of screw holes (12) is 7, which are used to install screws, and the screws are used to connect the carcass (10) and the outer stopper (11); the number of numerical control reference holes (13) is 2, with a diameter of φ10H7, and they are respectively located on both sides of the outer stopper (11).

6. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 2, characterized in that: The base plate (1) and the upper template (2) are made of A3 carbon structural steel, and the carcass (10) tooling is made of A3 carbon structural steel; the width of the upper template (2) is 30 mm greater than the cross-sectional width of the part, and the height of the upper template (2) is 20 mm greater than the height of the part.

7. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 3, characterized in that: The material of the upper die (6) is Q235-AF carbon structural steel, with a material specification of 65 mm and an outer dimension of 265×70×65 mm. A groove is CNC milled downward from the end of one side of the top surface of the upper die (6). The starting position of the groove is 12 mm away from the end of the top surface, the length of the groove is 265 mm, the width of the groove is 12.5 mm, and the depth of the groove is 8 mm.

8. The method for processing the 5A90 aluminum-lithium alloy double-curvature L-shaped profile according to claim 3, characterized in that: The material of the lower die (7) is Q235-AF carbon structural steel, with a material specification of 33 mm and an outer dimension of 265×85×33 mm. The upper surface of the lower die (7) is processed by CNC milling according to the sinking depth and transition zone width of the part.

Images