Aluminum lithium alloy skin panel superplastic forming / gas quenching method and die

Abstract

The application relates to an aluminum-lithium alloy skin wall plate superplastic forming / gas quenching method and a die, and belongs to the technical field of metal plastic working, which solves the problems of low forming precision, low efficiency and high cost of the aluminum-lithium alloy skin wall plate prepared by the prior art. The aluminum-lithium alloy plate is subjected to superplastic forming, and the aluminum-lithium alloy plate subjected to the superplastic forming is subjected to gas quenching, so that the manufactured aluminum-lithium alloy skin wall plate not only has high profile precision, but also has high tensile strength performance, the process flow is simple, the processing cost is low, and the aluminum-lithium alloy skin wall plate has good integrity and consistency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal plastic working, and relates to an aluminum-lithium alloy skin wall plate superplastic forming / gas quenching method and a die, which is suitable for aluminum-lithium alloy skin wall plate manufacturing. BACKGROUND

[0002] With the development of aerospace technology, lightweight and high performance have become the inevitable choice of structural design. As a kind of light metal material, the density of aluminum-lithium alloy is lower than that of ordinary aluminum alloy due to the addition of Li element, and the elastic modulus is higher. The addition of 1% Li element can reduce the density of aluminum-lithium alloy by 3%, while the elastic modulus is increased by 6%, and the hardening effect of the alloy after quenching and artificial aging is good. In addition, the aluminum-lithium alloy has excellent corrosion resistance, good low temperature performance and fatigue resistance, and has broad application prospects in aerospace and other fields such as rail transportation, automobile electronics and nuclear industry. With the wide application of aluminum-lithium alloy structural parts, the research on aluminum-lithium alloy skin wall plate manufacturing is particularly important. At present, the manufacturing methods of aluminum-lithium alloy skin wall plate mainly include drawing forming, creep aging forming and roll forming processes, but the forming precision is not high, the efficiency is low, the cost is high and other factors, which greatly hinder the application of aluminum-lithium alloy skin wall plate. SUMMARY

[0003] Based on the above analysis, the application aims to provide an aluminum-lithium alloy skin wall plate superplastic forming / gas quenching method and die, which solves the problems of low forming precision, low efficiency and high cost of the aluminum-lithium alloy skin wall plate prepared by the prior art.

[0004] The purpose of the application is mainly realized through the following technical solutions:

[0005] On the one hand, the application provides an aluminum-lithium alloy skin wall plate superplastic forming / gas quenching method, which comprises the following steps:

[0006] Step 1: superplastic forming of aluminum-lithium alloy plate;

[0007] Step 2: gas quenching of the superplastically formed aluminum-lithium alloy plate.

[0008] Further, the step 1 superplastic forming process comprises:

[0009] Step 11: n round holes are made on the top of the aluminum-lithium alloy plate, the superplastic forming upper die and the superplastic forming lower die are heated to a preset temperature, and the aluminum-lithium alloy plate is placed between the superplastic forming upper die and the superplastic forming lower die and kept for 10-30 min;

[0010] Step 12: gas is introduced between the aluminum-lithium alloy sheet and the superplastic forming upper die through the superplastic forming upper die gas inlet, and the aluminum-lithium alloy sheet gradually adheres to the superplastic forming lower die.

[0011] Further, the step 2 gas quenching process includes:

[0012] Step 21: after the aluminum-lithium alloy sheet completely adheres to the superplastic forming lower die cavity, the superplastic forming upper die is removed, a hook is placed in the top circular hole of the aluminum-lithium alloy sheet, the gas quenching die is connected to the aluminum-lithium alloy sheet through the hook, and the gas quenching die is placed above the aluminum-lithium alloy sheet, and the protruding part of the gas quenching die is completely placed in the superplastic forming lower die cavity.

[0013] Step 22: the gas quenching die and the aluminum-lithium alloy sheet are moved upward together, and at the same time, gas is introduced through the gas quenching die gas inlet, and the gas is discharged through the gas quenching die gas outlet, forming a gas quenching layer between the gas quenching die and the aluminum-lithium alloy sheet.

[0014] Step 23: after the aluminum-lithium alloy sheet cools to room temperature, the aluminum-lithium alloy sheet is removed from the gas quenching die.

[0015] Further, in the above step 11, the superplastic forming upper die has an upper die cavity, the side of the upper die cavity has an upper die gas inlet communicating with the upper die cavity, and the fluid forming lower die has a lower die cavity.

[0016] Further, in the above step 11, the preset temperature range is 450-550°C.

[0017] Further, in the above step 12, gas is introduced between the aluminum-lithium alloy sheet and the superplastic forming upper die through the superplastic forming upper die gas inlet, and the gas is nitrogen or argon.

[0018] Further, in the above step 12, gas is introduced between the aluminum-lithium alloy sheet and the superplastic forming upper die through the superplastic forming upper die gas inlet, and the gas pressure is 0.3-3 MPa.

[0019] Further, in the above step 21, the gas quenching die has a gas quenching die gas inlet and a gas quenching die gas outlet, and the shape of the protruding part of the gas quenching die is consistent with the shape of the lower die cavity. The gap between the aluminum-lithium alloy sheet and the gas quenching die is t, which satisfies the relationship t≤0.5×T, where T is the thickness of the aluminum-lithium alloy sheet.

[0020] Further, in the above step 22, the gas quenching die and the aluminum-lithium alloy sheet are moved upward together, and at the same time, gas is introduced through the gas quenching die gas inlet, and the gas pressure is P, and the aluminum-lithium alloy sheet thickness T exists the relationship P=γ×T, γ=0.1-0.2 MPa / mm, P is in MPa, and T is in mm.

[0021] Further, in step 22, the gas is preferably introduced through the gas inlet of the gas quenching mold, and the gas is helium, nitrogen or argon.

[0022] The application also provides an aluminum-lithium alloy skin panel superplastic forming / gas quenching mold for realizing the above-mentioned superplastic forming / gas quenching method, comprising a superplastic forming upper mold, a superplastic forming lower mold and a gas quenching mold.

[0023] The superplastic forming upper mold has an upper mold cavity, and an upper mold gas inlet is arranged on the side of the upper mold cavity and communicates with the upper mold cavity; the superplastic forming lower mold has a lower mold cavity, and the lower mold cavity is a groove; the top fillet r and the bottom fillet R of the superplastic forming lower mold satisfy the relationship R≥0.5×T and r≥2×T, where T is the thickness of the aluminum-lithium alloy panel; the groove width f and the groove depth h of the lower mold cavity satisfy the relationship f≥h; the upper mold cavity is square, and has a length c and a width g; and the width e of the upper mold gas inlet satisfies the relationship c>f and g>e.

[0024] The gas quenching mold has a gas quenching mold gas inlet and a gas quenching mold gas outlet, and the shape of the convex part of the gas quenching mold is consistent with the shape of the superplastic forming lower mold cavity.

[0025] The length of the aluminum-lithium alloy panel is a, the gas quenching mold has M gas quenching mold gas outlets, the spacing between adjacent gas quenching mold gas outlets is b, the diameter of the gas quenching mold gas outlet 9 is d, and the relationship b≤a×d / 10 is satisfied; the number M of the gas quenching mold gas outlets 9 satisfies the relationship M≥a / b; and a, b and d are in millimeters.

[0026] Compared with the prior art, the application can achieve at least one of the following beneficial effects:

[0027] (1) Compared with the cold forming process, the profile accuracy of the aluminum-lithium alloy skin panel manufactured by the application is improved from ±1mm to ±0.3mm, and the profile accuracy is higher and the size consistency is better;

[0028] (2) Compared with single superplastic forming, the tensile strength of the aluminum-lithium alloy skin panel manufactured by the application can be improved by more than 20%, and the tensile strength is higher and the part bearing performance is better;

[0029] (3) Compared with the casting process, the weight control of the aluminum-lithium alloy skin panel manufactured by the application is accurate, the weight reduction effect is better, and the weight is reduced by more than 10%;

[0030] (4) Compared with the heat treatment or shaping after forming, the application saves the manual shaping process, the cost is reduced from 5000 yuan / piece to 4000 yuan / piece, the process flow is simple, and the processing cost is low;

[0031] (5) Compared with the forming+splicing welding scheme, the application can manufacture complex special-shaped curved surface aluminum lithium alloy skin wall plates such as non-circular arc and plane, irregular curved surface, can realize overall forming of a length of 2m parts, does not need splicing welding, and the prepared aluminum lithium alloy skin wall plate has better integrity and consistency. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Schematic diagram before superplastic forming of the aluminum lithium alloy skin wall plate;

[0033] Figure 2 Schematic diagram after superplastic forming of the aluminum lithium alloy skin wall plate;

[0034] Figure 3 Schematic diagram before gas quenching of the aluminum lithium alloy skin wall plate;

[0035] Figure 4 Schematic diagram after gas quenching of the aluminum lithium alloy skin wall plate.

[0036] Figure 5 Aluminum lithium alloy skin wall plate;

[0037] Figure 6 Superplastic forming / gas quenching flowchart of the aluminum lithium alloy skin wall plate.

[0038] The drawings show that: 1 is an aluminum lithium alloy plate, 2 is an upper superplastic forming die, 3 is a gas inlet of the upper superplastic forming die, 4 is a lower superplastic forming die, 5 is a cavity of the upper die, 6 is a cavity of the lower die, 7 is a gas quenching die, 8 is a gas inlet of the gas quenching die, 9 is a gas outlet of the gas quenching die, 10 is a gas quenching layer, a is the length of the aluminum lithium alloy plate, b is the spacing between adjacent gas outlets of the gas quenching die, d is the diameter of the gas outlet of the gas quenching die, r is the top round angle of the lower superplastic forming die, R is the bottom round angle of the lower superplastic forming die, f is the width of the groove of the lower die cavity, h is the depth of the groove of the lower die cavity, c is the length of the upper die cavity, g is the width of the upper die cavity, e is the width of the upper gas inlet, T is the thickness of the aluminum lithium alloy plate, and t is the gap between the aluminum lithium alloy plate and the gas quenching die. DETAILED DESCRIPTION

[0039] The preferred embodiments of the application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of the application and serve to explain the principles of the embodiments of the application, but are not used to limit the scope of the application.

[0040] At present, the manufacturing methods of aluminum lithium alloy skin wall plates mainly include drawing forming, creep aging forming, and roll bending forming, but the forming precision is not high, the efficiency is low, the cost is high, and other factors greatly hinder the application of aluminum lithium alloy skin wall plates.

[0041] The application provides an aluminum-lithium alloy skin wallboard superplastic forming / gas quenching method.

[0042] Compared with the prior art, the aluminum-lithium alloy plate is first superplastically formed through a superplastic forming die, then the superplastically formed aluminum-lithium alloy plate is gas quenched through a gas quenching die, and finally the aluminum-lithium alloy skin wallboard prepared has high profile accuracy and high tensile strength performance, the process flow is simple, the processing cost is low, and the aluminum-lithium alloy skin wallboard has good integrity and consistency.

[0043] The application provides an aluminum-lithium alloy skin wallboard superplastic forming / gas quenching method, which comprises the following steps:

[0044] Step 1: superplastic forming of an aluminum-lithium alloy plate;

[0045] Step 2: gas quenching of the superplastically formed aluminum-lithium alloy plate.

[0046] Specifically, in step 1, the aluminum-lithium alloy plate is superplastically formed, and the superplastic forming process comprises the following steps:

[0047] Step 11: forming n round holes on the top of the aluminum-lithium alloy plate 1, heating the superplastic forming upper die 2 and the superplastic forming lower die 4 to a preset temperature, and placing the aluminum-lithium alloy plate 1 between the superplastic forming upper die 2 and the superplastic forming lower die 4 and keeping warm for 10-30 min;

[0048] Step 12: introducing gas between the aluminum-lithium alloy plate 1 and the superplastic forming upper die 2 through the superplastic forming upper die gas inlet 3, and the aluminum-lithium alloy plate gradually adheres to the superplastic forming lower die 4;

[0049] Specifically, in step 11, the setting temperature is determined by the forming characteristics of the aluminum-lithium alloy plate material itself, and within the temperature range required for material forming, the temperature corresponding to the high elongation rate of the material is selected as much as possible, and the preset temperature range is 450-550 DEG C. For example, 450 DEG C, 480 DEG C, 500 DEG C, 550 DEG C. Through the heat preservation operation, the aluminum-lithium alloy plate is heated more uniformly, and the deformation ability is better. The length of the aluminum-lithium alloy plate is a, in mm, and 1 round hole is formed on the top of the aluminum-lithium alloy plate every 50 mm, and the number of round holes n=a / 50.

[0050] Specifically, in step 11, the superplastic forming upper die 2 has an upper die cavity 5 left thereon, the upper die cavity 5 has an upper die gas inlet 3 left on the side surface thereof and in communication with the upper die cavity 5, and the superplastic forming lower die 4 has a lower die cavity 6 left thereon; the lower die cavity 6 is a groove.

[0051] Specifically, in step 12, the gas is usually selected as nitrogen or argon, and a certain gas pressure is maintained to make the aluminum-lithium alloy plate 1 and the superplastic forming lower mold 4 completely adhere, and the gas pressure ranges from 0.3 MPa to 3 MPa, for example, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, or 2.5 MPa.

[0052] Specifically, in step 2, the aluminum-lithium alloy plate subjected to superplastic forming is subjected to gas quenching, and the gas quenching process includes:

[0053] Step 21: After the aluminum-lithium alloy plate 1 completely adheres to the superplastic forming lower mold cavity 6, the superplastic forming upper mold 2 is removed, a hook is placed in the top circular hole of the aluminum-lithium alloy plate 1, the gas quenching mold 7 is connected to the aluminum-lithium alloy plate 1 through the hook, and is placed above the aluminum-lithium alloy plate 1, and the protruding part of the gas quenching mold 7 is completely placed in the superplastic forming lower mold cavity 6.

[0054] Step 22: The gas quenching mold 7 and the aluminum-lithium alloy plate 1 are moved upward together, and at the same time, gas is introduced through the gas quenching mold gas inlet 8, and the gas is discharged through the gas quenching mold gas outlet 9, thereby forming a gas quenching layer 10 between the gas quenching mold 7 and the aluminum-lithium alloy plate 1.

[0055] Step 23: After the aluminum-lithium alloy plate 1 is cooled to room temperature, the aluminum-lithium alloy plate 1 is removed from the gas quenching mold 7.

[0056] Specifically, in step 21, the gas quenching mold 7 has a gas quenching mold gas inlet 8 and a gas quenching mold gas outlet 9, and the shape of the protruding part of the gas quenching mold 7 is consistent with the shape of the lower mold cavity. The protruding part of the gas quenching mold 7 has the same number of circular holes as the position of the top circular hole of the aluminum-lithium alloy plate. The gap between the aluminum-lithium alloy plate 1 and the gas quenching mold 7 is t, which satisfies the relationship t≤0.5×T, where T is the thickness of the aluminum-lithium alloy plate, and the relationship can ensure that the gas quenching effect is sufficient.

[0057] Specifically, in step 22, the length of the aluminum-lithium alloy plate 1 is a, the gas quenching mold 7 has M gas quenching mold gas outlets 9, the distance between adjacent gas quenching mold gas outlets 9 is b, the diameter of the gas quenching mold gas outlet is d, and the relationship b≤a×d / 10 is satisfied, and the number of gas quenching mold gas outlets 9 M≥a / b, and the units of a, b, and d are mm.

[0058] The gas is introduced through the gas quenching mold gas inlet 8, and the gas pressure is P, and there is a relationship P=γ×T between the thickness T of the aluminum-lithium alloy plate 1 and the gas pressure P, and γ=0.1 MPa / mm~0.2 MPa / mm, and the unit of P is MPa and the unit of T is mm.

[0059] The gas is usually helium, nitrogen or argon, and the greater the pressure of the gas, the better the mechanical properties of the prepared aluminum lithium alloy wall plate skin, but too great pressure of the gas can easily cause the prepared part to deform, so a suitable pressure of the gas needs to be selected to meet the above relationship, so as to ensure that the gas quenching effect is good.

[0060] Specifically, in step 23, the aluminum lithium alloy plate 1 is cooled, and the gas quenching layer 10 is used to achieve the relationship in step 22, and the gas is continuously introduced until the aluminum alloy plate is cooled to room temperature, and whether the aluminum alloy plate is cooled to room temperature is detected by an infrared temperature measuring device.

[0061] The application also provides an aluminum lithium alloy skin wall plate superplastic forming / gas quenching die for realizing the above-mentioned superplastic forming / gas quenching method, which comprises a superplastic forming upper die 2, a superplastic forming lower die 4 and a gas quenching die 7.

[0062] The superplastic forming upper die 2 has an upper die cavity 5, and the side of the upper die cavity 5 is provided with an upper die gas inlet 3 communicating with the upper die cavity 5. The superplastic forming lower die 4 has a lower die cavity 6, which is a groove. The gas quenching die 7 has a gas quenching die gas inlet 8 and a gas quenching die gas outlet 9. The gas quenching die gas inlet 8 is a horizontal through channel structure, and the gas quenching die gas outlet 9 is vertically communicated with the through direction of the gas quenching die gas inlet 8. The number of the gas quenching die gas outlet 9 is M≥a / b (wherein a is the length of the aluminum lithium alloy plate, b is the spacing between adjacent gas quenching die gas outlets, d is the diameter of the gas quenching die gas outlet, and there is a relationship b≤a×d / 10, and the units of a, b and d are m). The shape of the protruding part of the gas quenching die 7 is consistent with the shape of the superplastic forming lower die cavity, and the protruding part of the gas quenching die 7 has the same number of round holes as the position of the round hole at the top of the aluminum lithium alloy plate.

[0063] Specifically, the thickness T of the aluminum lithium alloy plate 1, the top round angle r and the bottom round angle R of the superplastic forming lower die 4, and the groove width f and the groove depth h of the lower die cavity 6 satisfy the relationships R≥0.5×T, r≥2×T and f≥h. The upper die cavity 5 is square, with a length c and a width g, and the width e of the upper die gas inlet 3 satisfies c>f and g>e. Satisfying such relationships can ensure that the formed part is successfully formed without breaking during the forming process.

[0064] The thickness of the aluminum lithium alloy plate 1 is T, and the gap between the aluminum lithium alloy plate 1 and the gas quenching die 7 is t, which satisfies the relationship t≤0.5×T. The length of the aluminum lithium alloy plate 1 is a, the gas quenching die 7 has M gas quenching die gas outlets 9, the spacing between adjacent gas quenching die gas outlets 9 is b, the diameter of the gas quenching die gas outlet 9 is d, and there is a relationship b≤a×d / 10. The number of the gas quenching die gas outlet 9 is M≥a / b, and the units of a, b and d are mm.

[0065] When the aluminum-lithium alloy skin wallboard is formed by using the mold, the aluminum-lithium alloy plate is placed between the superplastic forming upper mold and the superplastic forming lower mold which are heated to a preset temperature, the gas is introduced between the aluminum-lithium alloy plate and the superplastic forming upper mold through the superplastic forming upper mold gas inlet, and the aluminum-lithium alloy plate gradually adheres to the superplastic forming lower mold; after the aluminum-lithium alloy plate completely adheres to the cavity of the superplastic forming lower mold, the superplastic forming upper mold is removed, the hook is placed in the top circular hole of the aluminum-lithium alloy plate, the gas quenching mold is connected with the aluminum-lithium alloy plate through the hook and is placed above the aluminum-lithium alloy plate, and the protruding part of the gas quenching mold is completely placed in the cavity of the superplastic forming lower mold; the gas is introduced through the gas quenching mold gas inlet and is discharged through the gas quenching mold gas outlet, so that the gas quenching layer is formed between the gas quenching mold and the aluminum-lithium alloy plate.

[0066] The aluminum-lithium alloy skin wallboard is first superplastically formed by the superplastic forming mold, then the superplastically formed aluminum-lithium alloy plate is gas quenched by the gas quenching mold, and finally the aluminum-lithium alloy skin wallboard has high surface precision and high tensile strength performance, the process flow is simple, the processing cost is low, and the aluminum-lithium alloy skin wallboard has good integrity and consistency.

[0067] Embodiment 1

[0068] The aluminum-lithium alloy skin wallboard superplastic forming / gas quenching method of the embodiment comprises the following steps:

[0069] Step 1: superplastically forming the aluminum-lithium alloy plate;

[0070] Step 11: forming n circular holes on the top of the aluminum-lithium alloy plate, heating the superplastic forming upper mold 2 and the superplastic forming lower mold 4 to a preset temperature, and placing the aluminum-lithium alloy plate 1 between the superplastic forming upper mold 2 and the superplastic forming lower mold 4; the preset temperature is 500 DEG C, and the holding time is 15 min. The length of the aluminum-lithium alloy plate 1 is a=300 mm, one circular hole is formed on the top of the aluminum-lithium alloy plate every 50 mm, and the number of circular holes n=a / 50=6.

[0071] Step 12: introducing the gas between the aluminum-lithium alloy plate 1 and the superplastic forming upper mold 2 through the superplastic forming upper mold gas inlet 3, and the aluminum-lithium alloy plate 1 gradually adheres to the superplastic forming lower mold 4; the introduced gas is nitrogen, and the gas pressure is 1 MPa.

[0072] Step 2: gas quenching the superplastically formed aluminum-lithium alloy plate.

[0073] Step 21: after the aluminum-lithium alloy sheet 1 is completely and superplastically formed to fit the lower die cavity 6, the upper superplastic forming die 2 is removed, a hook is placed in the top circular hole of the aluminum-lithium alloy sheet 1, the gas quenching die 7 is connected to the aluminum-lithium alloy sheet 1 through the hook, and the gas quenching die 7 is placed above the aluminum-lithium alloy sheet 1, with the gas quenching die protruding part completely placed in the superplastic forming lower die cavity 6.

[0074] Step 22: the gas quenching die 7 and the aluminum-lithium alloy sheet 1 are moved upward together, at the same time, gas is introduced through the gas quenching die gas inlet 8, and the gas is discharged through the gas quenching die gas outlet 9, forming a gas quenching layer 10 between the gas quenching die 7 and the aluminum-lithium alloy sheet 1; the gas introduced through the gas quenching die gas inlet 8 has a pressure of P=0.2 MPa, the thickness of the aluminum-lithium alloy sheet 1 is T=2 mm, and γ=0.1 MPa / mm, which satisfies the relationship P=γ×T, γ=0.1 MPa / mm~0.2 MPa / mm, P is in MPa, and T is in mm. The gas introduced through the gas quenching die gas inlet 8 is argon.

[0075] Step 23: after the aluminum-lithium alloy sheet 1 is cooled to room temperature, the aluminum-lithium alloy sheet 1 is removed from the gas quenching die 7, and the temperature is measured using an infrared temperature measuring device.

[0076] The above-mentioned superplastic forming / gas quenching method uses a die including an upper superplastic forming die 2, a lower superplastic forming die 4, and a gas quenching die 7.

[0077] The upper superplastic forming die 2 has an upper die cavity 5, and the side of the upper die cavity 5 has an upper die gas inlet 3 communicating with the upper die cavity 5. The lower superplastic forming die 4 has a lower die cavity 6, which is a groove. The thickness of the aluminum-lithium alloy sheet 1 is T=2 mm, the top round corner of the lower superplastic forming die 4 is r=4 mm, and the bottom round corner is R=2 mm, which satisfies the relationship R≥0.5×T and r≥2×T. The groove width f of the lower die cavity 6 is 20 mm, and the groove depth h is 20 mm, which satisfies the relationship f≥h. The upper die cavity 5 is square, with a length c=25 mm and a width g=4 mm. The width of the upper die gas inlet 3 is e=2 mm, and c>e and g>e.

[0078] The gas quenching die 7 has a gas quenching die gas inlet 8 and a gas quenching die gas outlet 9. The shape of the gas quenching die protruding part is consistent with that of the superplastic forming lower die cavity. The gas quenching die 7 has the same number of circular holes as the position of the top circular hole of the aluminum-lithium alloy sheet.

[0079] In the superplastic forming, the aluminum-lithium alloy sheet 1 is located between the superplastic forming upper die 2 and the superplastic forming lower die 4, and in the gas quenching, the aluminum-lithium alloy sheet 1 is located between the gas quenching die 7 and the superplastic forming lower die 4. The thickness of the aluminum-lithium alloy sheet 1 is selected as T=2mm, the gap between the aluminum-lithium alloy sheet 1 and the gas quenching die 7 is selected as t=0.5mm, and the relationship t≤0.5×T is met. The length of the aluminum-lithium alloy sheet 1 is selected as a=300mm, there are M gas quenching die gas outlets 9 on the gas quenching die 7, the spacing between adjacent gas quenching die gas outlets 9 is b=50mm, the diameter of the gas quenching die gas outlet 9 is d=2mm, the relationship b≤a×d / 10=300×2 / 10=60 is met, and the number of the gas quenching die gas outlets 9 is M≥a / b=5. The units of a, b and d are mm.

[0080] The aluminum-lithium alloy skin wall panel profile precision prepared by the method is ±0.3mm, the tensile strength of the aluminum-lithium alloy skin wall panel can reach more than 90% of the aluminum-lithium alloy sheet, the surface roughness Ra is 3.2, the structure weight is reduced by more than 10%, and the processing cycle is shortened by 30%. The specific performance indicators of Example 1 are shown in the following table.

[0081]

[0082] Example 2

[0083] In this embodiment, in step 11, the preset temperature is selected as 515℃, the holding time is 10min, and the other processing conditions are the same as those in Example 1.

[0084] Compared with the existing process, the aluminum-lithium alloy skin wall panel prepared by the embodiment can further improve the tensile strength of the aluminum-lithium alloy skin wall panel, which can reach more than 95% of the aluminum-lithium alloy sheet, and can reduce the structure weight by more than 5%, which is very important for aerospace products.

[0085] Example 3

[0086] In this embodiment, in step 12, the gas introduced is nitrogen, the gas pressure is 2MPa, and the other processing conditions are the same as those in Example 1.

[0087] Compared with the existing process, the aluminum-lithium alloy skin wall panel prepared by the embodiment can further improve the profile precision of the aluminum-lithium alloy skin wall panel, which can reach ±0.2mm, and can reduce the structure weight by more than 5%, which is very important for aerospace products.

[0088] Example 4

[0089] In this embodiment, in step 22, the gas introduced through the gas inlet 8 of the gas quenching die is helium, and the other processing conditions are the same as those in Example 1.

[0090] Compared with the prior art, the aluminum-lithium alloy skin wallboard prepared by the embodiment can further improve the tensile strength of the aluminum-lithium alloy skin wallboard, which can reach more than 95% of the aluminum-lithium alloy plate, and can make the structure weight reduce more than 5%, which is very important for aerospace products.

[0091] Example 5

[0092] In the embodiment, the aluminum-lithium alloy plate 1 and the gas quenching mold 7 are inverted before being moved upward in step 22, and other processing conditions are the same as those in example 1.

[0093] Compared with the prior art, the aluminum-lithium alloy skin wallboard prepared by the embodiment can further improve the profile accuracy of the aluminum-lithium alloy skin wallboard, which can reach ±0.2mm, which is very important for aerospace products.

[0094] Comparative Example 1

[0095] The superplastic forming / gas quenching mold is selected, the thickness of the aluminum-lithium alloy plate 1 is T=2mm, the gap between the aluminum-lithium alloy plate 1 and the gas quenching mold 7 is t=1.2mm, which does not satisfy the relationship t≤0.5×T. The length of the aluminum-lithium alloy plate 1 is a=200mm, the gas quenching mold 7 has M gas quenching mold outlets 7, the spacing between adjacent gas quenching mold outlets 7 is b=50mm, the diameter of the gas quenching mold outlet 7 is d=2mm, which does not satisfy the relationship b≤a×d / 10=200×2 / 10=40 and M≥a / b=4, and the units of a, b and d are mm.

[0096] The tensile strength of the aluminum-lithium alloy skin wallboard prepared by the embodiment is 510MPa.

[0097] Performance list of aluminum-lithium alloy skin wallboard of comparative examples and embodiments

[0098]

[0099]

[0100] Although the present application is disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present application, therefore, the protection scope of the present application should be defined by the scope of the claims of the present application.

Claims

1. A superplastic forming / gas quenching method for aluminum-lithium alloy skin panels, characterized in that: The superplastic forming / gas quenching method comprises the following steps: Step 1: superplastic forming the aluminum-lithium alloy plate; Step 2: Gas quenching the superplastic formed aluminum-lithium alloy plate; Step 1 includes: Step 11: Create n circular holes on the top of the aluminum-lithium alloy plate, heat the superplastic forming upper die and the superplastic forming lower die to a preset temperature, place the aluminum-lithium alloy plate between the superplastic forming upper die and the superplastic forming lower die and keep them warm for 10 to 30 minutes; Step 12: introducing gas between the aluminum-lithium alloy plate and the superplastic forming upper die through the air inlet of the superplastic forming upper die, so that the aluminum-lithium alloy plate gradually fits toward the superplastic forming lower die; Step 2 includes: Step 21: After the aluminum-lithium alloy plate is completely fitted into the superplastic forming lower mold cavity, the superplastic forming upper mold is removed, a hook is placed in the circular hole on the top of the aluminum-lithium alloy plate, and the gas quenching mold is connected to the aluminum-lithium alloy plate via the hook and placed above the aluminum-lithium alloy plate, with the raised portion of the gas quenching mold completely placed in the superplastic forming lower mold cavity; Step 22: The gas quenching mold and the aluminum-lithium alloy plate are moved upward together. At the same time, gas is introduced through the gas inlet of the gas quenching mold and discharged through the gas outlet of the gas quenching mold to form a gas quenching layer between the gas quenching mold and the aluminum-lithium alloy plate. Step 23: After the aluminum-lithium alloy plate is cooled to room temperature, the aluminum-lithium alloy plate is removed from the gas quenching mold; In step 22, gas is introduced through the gas inlet of the gas quenching mold, wherein the gas is helium, nitrogen or argon; In step 22, the gas quenching die and the aluminum-lithium alloy plate are moved upward together. At the same time, gas is introduced through the gas inlet of the gas quenching die. The gas pressure is P, and the relationship between the gas pressure and the thickness T of the aluminum-lithium alloy plate is P=γ×T, where γ=0.1MPa / mm to 0.2MPa / mm, where P is in MPa and T is in mm. An upper mold cavity is left on the superplastic forming upper mold, and an upper mold air inlet connected to the upper mold cavity is left on the side of the upper mold cavity; a lower mold cavity is left on the superplastic forming lower mold, and the lower mold cavity is a groove; The gas quenching mold has an air inlet and an air outlet. The air inlet of the gas quenching mold is a horizontal through-channel structure. The air outlet of the gas quenching mold is vertically connected to the through-direction of the air inlet of the gas quenching mold. The raised portion of the gas quenching mold has the same number of circular holes as the positions of the circular holes on the top of the aluminum-lithium alloy plate. The shape of the raised portion of the gas quenching mold is consistent with the shape of the cavity of the superplastic forming lower mold. The top fillet r and the bottom fillet R of the superplastic forming lower die have a relationship of R ≥ 0.5 × T and r ≥ 2 × T, wherein T is the thickness of the aluminum-lithium alloy plate, the groove width of the lower die cavity is f, the groove depth is h, and the following conditions are met: f ≥ h, the upper die cavity is square, the length is c, the width is g, and the width of the upper die air inlet is e, and the following conditions are met: c > f, g > e; The length of the aluminum-lithium alloy plate is a, there are M gas quenching mold air outlets on the gas quenching mold, the spacing between adjacent gas quenching mold air outlets is b, the diameter of the gas quenching mold air outlet is d, and there is a relationship b≤a×d / 10, the number of gas quenching mold air outlets M≥a / b, and the units of a, b, and d are m.

2. The superplastic forming / gas quenching method of aluminum-lithium alloy skin panels according to claim 1, characterized in that: The preset temperature range is 450°C to 550°C.

3. The superplastic forming / gas quenching method of aluminum-lithium alloy skin panels according to claim 1, characterized in that: Gas is introduced between the aluminum-lithium alloy plate and the superplastic forming upper die through the gas inlet of the superplastic forming upper die, and the gas is nitrogen or argon.

4. The superplastic forming / gas quenching method of aluminum-lithium alloy skin panels according to claim 1, characterized in that: Gas is introduced between the aluminum-lithium alloy plate and the superplastic forming upper die through the gas inlet of the superplastic forming upper die, and the gas pressure range is 0.3 MPa~3 MPa.

5. The superplastic forming / gas quenching method of aluminum-lithium alloy skin panel according to claim 1, characterized in that: The gas quenching mold has a gas quenching mold air inlet and a gas quenching mold air outlet, and the shape of the convex part of the gas quenching mold is consistent with the shape of the lower mold cavity; The gap between the aluminum-lithium alloy plate and the gas quenching die is t, which satisfies the relationship t≤0.5×T, where T is the thickness of the aluminum-lithium alloy plate.

6. A superplastic forming / gas quenching die for aluminum-lithium alloy skin panels, used to implement the superplastic forming / gas quenching method according to any one of claims 1 to 5, characterized in that: include: Superplastic forming upper die, superplastic forming lower die, gas quenching die; The upper mold cavity is left on the superplastic forming upper mold, and the upper mold air inlet connected to the upper mold cavity is left on the side of the upper mold cavity. The lower mold cavity is left on the superplastic forming lower mold, and the lower mold cavity is a groove. The top fillet r and the bottom fillet R of the superplastic forming lower mold have a relationship R≥0.5×T, r≥2×T, where T is the thickness of the aluminum-lithium alloy plate, the groove width of the lower mold cavity is f, and the groove depth is h, satisfying: f≥h, The upper mold cavity is square, with a length of c and a width of g. The width of the upper mold air inlet is e, satisfying the following conditions: c>f, g>e; The gas quenching mold has an air inlet and an air outlet. The air inlet of the gas quenching mold is a horizontal through-channel structure. The air outlet of the gas quenching mold is vertically connected to the through-direction of the air inlet of the gas quenching mold. The raised portion of the gas quenching mold has the same number of circular holes as the positions of the circular holes on the top of the aluminum-lithium alloy plate. The shape of the raised portion of the gas quenching mold is consistent with the shape of the cavity of the superplastic forming lower mold. The length of the aluminum-lithium alloy plate is a, there are M gas quenching mold air outlets on the gas quenching mold, the spacing between adjacent gas quenching mold air outlets is b, the diameter of the gas quenching mold air outlet is d, and there is a relationship b≤a×d / 10, the number of gas quenching mold air outlets M≥a / b, and the units of a, b, and d are m.

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