A method for suppressing wrinkling of thin-walled components of tank bottom by creep aging forming

Abstract

The present invention discloses a method for suppressing wrinkling of thin-walled components of the bottom of a storage tank by creep aging forming. The method comprises obtaining parameters of the original plate and parameters of the target component; performing finite element simulation to obtain the high wrinkling risk area of ​​the original plate; determining relevant information of the edge clamping device according to the stress-strain state change of the high wrinkling risk area; wrapping the original plate as a whole with a layer of breathable felt, placing it on a forming mold, sealing it with a first layer of vacuum bag, and evacuating it outside the autoclave; covering the upper surface of the first layer of vacuum bag with a layer of breathable felt, and placing the edge clamping device on the second layer of breathable felt corresponding to the corresponding placement area, sealing it with a second layer of vacuum bag, and evacuating it outside the autoclave; controlling the creep aging forming process in the autoclave, and obtaining the target component after heat preservation and loading. The scheme of the present invention realizes precise creep aging forming of the bottom of the storage tank by sealing the vacuum bag and applying a certain pressure to the high wrinkling risk area as required by means of the pressure difference between the inside and outside of the bag.

Description

Technical Field

[0001] The invention relates to the technical field of creep aging forming of thin-walled components, and in particular to a method for suppressing wrinkling of creep aging forming of thin-walled components at the bottom of a tank. Background Art

[0002] As an important component of the rocket, the tank is used as a pressure vessel to store liquid hydrogen / liquid oxygen and other propellants required for rocket launch. As a key component of the rocket tank, the tank bottom bears the composite loads of internal pressure and vibration with a semi-ellipsoidal thin-walled shell structure. Considering the requirements of lightweight and economical rocket body structure, the thickness of the tank bottom will be greatly reduced, and the diameter-to-thickness ratio of the tank bottom will continue to break through the traditional limit, which puts higher requirements on the forming accuracy and service performance of the key rocket body tank bottom structure of the launch vehicle.

[0003] Creep aging forming is an advanced technology suitable for the overall shape-coordinated manufacturing of large and complex thin-walled components. It mainly utilizes the creep characteristics, stress relaxation characteristics and aging strengthening characteristics of metal materials to achieve the integration of target component forming and forming in the temperature field and stress field integrated in time and space. However, during the plastic forming process, thin plate components are prone to wrinkling and post-buckling large deformation under the action of circumferential compressive stress loads, making it difficult for the component's forming accuracy and service life to meet the target expectations.

[0004] During the creep aging forming process of thin plate components, the deformation behavior of the material is extremely complex. Due to their special geometric structure, thin-walled components such as tank bottoms are easily affected by stress concentration and uneven deformation during the forming process, and are prone to forming defects such as instability and wrinkling, which affects the forming quality and service life of the components. Therefore, reasonable measures need to be taken to suppress the wrinkling and instability of thin-walled components such as tank bottoms during the creep aging forming process to ensure high-precision forming of the components. Summary of the invention

[0005] In order to solve the technical problem that the existing thin-walled components are very likely to wrinkle during the creep aging forming process, an embodiment of the present invention provides a method for suppressing wrinkles during creep aging forming of a thin-walled component at the bottom of a tank.

[0006] The technical solution of the embodiment of the present invention is achieved as follows:

[0007] An embodiment of the present invention provides a method for suppressing wrinkling of a thin-walled component of a tank bottom during creep aging forming, the method comprising: obtaining parameters of an original plate and parameters of a target component; performing finite element simulation using the parameters of the original plate and the parameters of the target component to simulate the creep aging forming process of the original plate, and obtaining a high wrinkling risk area during the creep aging forming process of the original plate; obtaining a stress-strain state change in the high wrinkling risk area; determining the shape of a edge clamping device, the corresponding placement area of ​​the edge clamping device on the original plate, and the edge pressure to be applied by the edge clamping device according to the stress-strain state change in the high wrinkling risk area; After the original plate is cleaned, it is wrapped with a layer of breathable felt as a whole and placed on a forming mold. It is sealed with a first layer of vacuum bag and vacuumized outside the autoclave to position and fix the original plate and the forming mold. A layer of breathable felt is covered on the upper surface of the first layer of vacuum bag, and the edge holding device is placed on the second layer of breathable felt corresponding to the corresponding placement area. It is sealed with a second layer of vacuum bag and vacuumized outside the autoclave to apply the edge pressure to the edge holding device. The creep aging forming process is controlled in the autoclave, and after heat preservation and loading, the target component after creep aging forming is obtained.

[0008] In one embodiment, the original plate parameters include: the diameter, thickness and material of the original plate; the target component parameters include target forming depth and forming curvature; wherein, when the target component is a spherical structure, the forming curvature is a single curvature; when the target component is an ellipsoidal structure, the forming curvature is the semi-major axis length and semi-minor axis length of the ellipsoid.

[0009] In one embodiment, determining the edge pressure to be applied by the edge holding device includes: calculating the edge pressure to be applied by the edge holding device in a uniformly distributed load or concentrated force manner; the edge pressure is a constant force or a force that varies with the forming process.

[0010] In one embodiment, the shape of the edge clamping device includes a circular ring shape and a circular ring block shape, and determining the shape of the edge clamping device includes: determining the inner diameter, outer diameter and thickness of the edge clamping device; wherein the thickness of the edge clamping device is 3 to 10 times the thickness of the original plate; the outer diameter of the edge clamping device is based on half of the diameter of the original plate, increased by 0 to 10 mm, and the inner diameter of the edge clamping device is determined by the forming curvature of the original plate.

[0011] In one embodiment, when the thickness of the original plate is less than 1 mm, the thickness of the edge pressing device is 5 times the thickness of the original plate.

[0012] In one embodiment, the original plate and the forming mold are sealed using a first layer of vacuum bag, including: using high-temperature glue to tightly bond the first layer of vacuum bag to the surface of the forming mold; the high-temperature glue is a four-layer tape, the tape layers are directly connected to each other, and the width between the layers is between 1 / 3 and 1 / 4 of the tape width; after the tape is tightly bonded to the first layer of vacuum bag, a pressure plate is used to apply pressure to the bonding point to ensure reliable bonding.

[0013] In one embodiment, a first layer of vacuum bag is used for sealing, and a vacuum treatment is performed outside the autoclave, including: a vacuum treatment is performed outside the autoclave so that the pressure inside the first layer of vacuum bag is between -0.02 and 0.06 MPa.

[0014] In one embodiment, a second layer of vacuum bag is used for sealing, including: using high temperature glue to tightly bond the second layer of vacuum bag to the edge holding device, the original plate material and the surface of the forming mold; the high temperature glue is a three-layer tape, the tape layers are directly connected to each other, and the width between the layers is between 1 / 3 and 1 / 4 of the tape width; after the tape is tightly bonded to the second layer of vacuum bag, a pressure plate is used to apply pressure to the bonded part to ensure reliable bonding.

[0015] In one embodiment, a second vacuum bag is used for sealing, and a vacuum treatment is performed outside the autoclave, including: a vacuum treatment is performed outside the autoclave so that the pressure inside the second vacuum bag is the difference between the external atmospheric pressure and the side pressure.

[0016] In one embodiment, a vacuum treatment is performed outside the autoclave so that the pressure inside the second vacuum bag is the difference between the external atmospheric pressure and the side pressure, including: when the side pressure is a constant force, a vacuum treatment is performed outside the autoclave to constantly control the pressure inside the second vacuum bag to be the difference between the external atmospheric pressure and the side pressure; when the side pressure is a variable force, a vacuum treatment is performed outside the autoclave to dynamically control the pressure inside the second vacuum bag to be the difference between the external atmospheric pressure and the side pressure.

[0017] The beneficial effects of this embodiment are:

[0018] This embodiment creates a pressure difference between the external environment and the vacuum bag, and can apply a blanking force to the blanking ring in the autoclave. The applied blanking force is uniform and can be changed with the program, thereby achieving the purpose of suppressing the wrinkling of the bottom of the box. This embodiment can be used to achieve creep aging precision forming of components such as the bottom of the tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic flow chart of a method for suppressing wrinkling of a thin-walled component of a tank bottom by creep aging forming according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of a specific process of the wrinkle suppression method according to an embodiment of the present invention;

[0021] Figure 3 The schematic diagram of the outer shape of the edge holding device according to the embodiment of the present invention is shown in FIG. Figure 3 (a) is a schematic diagram showing that the edge holding device has a circular ring shape; Figure 3 (b) is a schematic diagram of the edge holding device with a circular ring-shaped block shape;

[0022] Figure 4 Schematic diagram of the sealing relationship of each layer in the wrinkle suppression method according to an embodiment of the present invention.

[0023] Description of Reference Numerals

[0024] 1-Second layer vacuum bag, 2-Blank holder, 3-First layer vacuum bag, 4-Sheet material, 5-Forming mold. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0026] The embodiment of the present invention provides a method for suppressing wrinkling of a thin-walled component of a tank bottom by creep aging forming, such as Figure 1 As shown, the method includes:

[0027] Step 101: Obtaining original plate parameters and target component parameters;

[0028] Step 102: performing finite element simulation using the original plate parameters and the target component parameters to simulate the creep aging forming process of the original plate and obtain a high wrinkling risk area during the creep aging forming process of the original plate;

[0029] Step 103: obtaining the stress-strain state change of the high wrinkling risk area; determining the shape of the edge holding device, the corresponding placement area of ​​the edge holding device on the original plate, and the edge pressure to be applied by the edge holding device according to the stress-strain state change of the high wrinkling risk area;

[0030] Step 104: After cleaning the original plate, wrap it with a layer of breathable felt as a whole, place it on the forming mold, seal it with a first layer of vacuum bag, and perform vacuum treatment outside the autoclave to position and fix the original plate and the forming mold;

[0031] Step 105: Covering the upper surface of the first vacuum bag with a layer of air-permeable felt, placing the edge pressing device on the second air-permeable felt corresponding to the corresponding placement area, sealing with the second vacuum bag, and performing vacuum treatment outside the autoclave to apply the edge pressure to the edge pressing device;

[0032] Step 106: Control the creep aging forming process in the autoclave, and obtain the target component after creep aging forming after heat preservation and load holding.

[0033] This embodiment provides a method for suppressing wrinkling during creep aging forming of tank bottom components, which aims to achieve precise creep aging forming of the tank bottom by applying a certain pressure to the high wrinkling risk area as needed through vacuum bag sealing and the pressure difference between the inside and outside of the bag.

[0034] See also Figure 2 The method of this embodiment specifically includes the following steps:

[0035] S1: Determine the relevant dimensions, material and other characteristics of the original plate and the relevant dimensions of the target box bottom.

[0036] Among them, the original sheet material diameter D, thickness t, target forming depth h and forming curvature ρ of the box bottom type components, the box bottom materials include but are not limited to stainless steel, aluminum alloy, etc., and when the box bottom type components are spherical structures, the target forming is a single curvature ρ, when the box bottom type components are ellipsoidal structures, the forming curvature is determined by the semi-major axis length a and the semi-minor axis length b of the ellipsoid.

[0037] S2: Determination of high wrinkling risk areas during creep aging forming of box bottom using finite element simulation.

[0038] Among them, finite element simulation software includes but is not limited to ANAYS, ABAQUS and MARC.MENTAT, and wrinkling simulation methods include but are not limited to eigenvalue buckling analysis and nonlinear buckling analysis (introducing initial defects: thickness defects, modal defects, material unevenness).

[0039] S3: Determine the edge pressure and the outer dimensions of the blank holder (i.e., the blank holder device) based on the stress / strain state changes in the high wrinkling risk area.

[0040] The blank holding force can be calculated as a uniformly distributed load or a concentrated force, and the blank holding force can be a constant force or a force that changes with the forming process.

[0041] Here, see Figure 3 , the blank holder can be in the shape of a ring, such as Figure 3 As shown in (a), it can also be in other shapes. For example, the edge of the block is pressed (i.e., the ring is divided into blocks), such as Figure 3 (b) As shown. Different edge clamp blocks can be designed. When the pressures required by the edge clamp blocks are the same, they can be sealed together. When the pressures of the edge clamp blocks are different, they can be distributed and sealed multiple times to achieve different pressure loading.

[0042] When the blank holder ring can be annular or divided into blocks, the outer dimensions of the blank holder ring mainly include the inner diameter R1, the outer diameter R2 and the thickness t3. The thickness t3 is generally 3-10 times the thickness t of the original sheet material. When t<1mm, t3=5t. The size of the outer diameter R2 is generally D / 2+ (0-10mm), and the inner diameter R1 is determined by referring to the forming curvature ρ.

[0043] S4: After the original sheet is cleaned, it is wrapped with a layer of breathable felt and then placed on the forming mold. The first layer of vacuum bag is sealed and vacuumed outside the autoclave.

[0044] Among them, the sealing method is to use high-temperature glue to tightly adhere the vacuum bag to the surface of the forming mold. The single-sided high-temperature glue is preferably four layers of tape. The width of the tape layers directly connected is 1 / 3-1 / 4 of the tape width. After the tape and the vacuum bag are tightly adhered, a pressure plate is used to apply pressure to the adhesion to ensure reliable adhesion; vacuum is drawn to make the pressure in the bag -0.02-0.06MPA.

[0045] S5: Cover the upper surface of the first vacuum bag with a layer of breathable felt, then place the blank holder determined in S3 on the second layer of breathable felt corresponding to the original plate, then seal the blank holder, the plate as a whole and the mold surface with a second vacuum bag, and evacuate the outside of the tank to apply the blank holder force.

[0046] Among them, when the second layer of bags is evacuated, the pressure inside the second layer of vacuum bags is the difference between the external atmospheric pressure and the required blank holding force (when the blank holding force is constant, it is a constant force; when the blank holding force is a variable value, the pressure difference can be changed with the program through program settings). When the second layer is vacuum sealed, three layers of single-sided high-temperature adhesive are preferably used. The width of the tape layers directly connected is 1 / 3-1 / 4 of the tape width. After the tape is tightly bonded to the vacuum bag, a pressure plate is used to apply pressure to the bonding point to ensure reliable bonding. The reason for the second layer of sealing is, first, to ensure the sealing of the forming process so that the component is evenly stressed during creep aging; second, to ensure the pressure of the blank holding ring;

[0047] S6: After creep aging in the tank, heat preservation and loading, the target component is obtained.

[0048] Among them, the aging temperature, creep loading pressure, aging time and creep loading rate of the creep aging forming of the component are determined with the help of finite element simulation.

[0049] This embodiment applies a blanking force through a blanking ring, thereby suppressing the wrinkling of box bottom components. Since part of the blanking force of box bottom components during creep aging forming is provided by the blanking ring, and the other part is maintained by the pressure difference between the inside and outside of the vacuum bag, the blanking situation during the creep aging process of the component is complicated. Considering that the pressure of the traditional blanking ring is mainly provided by hydraulic equipment, this embodiment uses the vacuum pressure of the autoclave to form a pressure difference between the external environment and the vacuum bag, and can apply a blanking force to the blanking ring in the autoclave. The blanking force applied to the blanking ring is uniform and can also be changed with the program, thereby achieving the purpose of suppressing the wrinkling of the box bottom.

[0050] Below, this solution will be described in detail based on a specific application embodiment.

[0051] See also Figure 4 Taking a spherical tank bottom made of stainless steel as an example, a method for suppressing wrinkling during creep aging forming of tank bottom components is provided. The specific steps are as follows:

[0052] S1: Determine the plate diameter D, thickness t, target forming depth h and forming curvature ρ of the required original plate.

[0053] S2: Construct a finite element simulation model for box bottom forming, embed the creep aging constitutive subroutine of the material used into the simulation model, and use wrinkling simulation finite element simulation to determine the high wrinkling risk area during the creep aging forming process of the box bottom.

[0054] Among them, finite element simulation software includes but is not limited to ANAYS, ABAQUS and MARC.MENTAT, and wrinkle simulation methods include but are not limited to eigenvalue buckling analysis and nonlinear buckling analysis (introducing initial defects: thickness defects, modal defects, material unevenness). The modal defect is generally selected from 5%-10% of the first-order buckling mode, and the thickness defect is generally selected from 1 / 10-1 / 5 of the plate thickness.

[0055] S3: Extract the stress / strain state changes of multiple Gaussian points in the high wrinkling risk area during the entire forming process, select the most dangerous Gaussian point / node to extract its pressure change, and thus determine the approximate change of the blank holding force. Determine the outer dimensions of the blank holding ring according to the wrinkling characteristics of the box bottom, the pressure changes of multiple Gaussian points / nodes and the original sheet size.

[0056] Among them, the blank holder force can be calculated as a uniform load or concentrated force. The blank holder force can be a constant force or a force that changes with the forming process. The outer dimensions of the blank holder ring mainly include the inner diameter R1, the outer diameter R2 and the thickness t3. The thickness t3 is generally 3-10 times the thickness t of the original sheet. When t<1mm, t3=5t. The size of the outer diameter R2 is generally D / 2+ (0-10mm), and the inner diameter R1 is determined by referring to the forming curvature ρ.

[0057] S4: After cleaning the original sheet, wrap a layer of breathable felt around the surface of the original sheet to prevent damage to the surface of the sheet, then place it on the forming mold, seal the first layer of vacuum bag, seal the sheet and the forming mold, and evacuate outside the autoclave.

[0058] Among them, the sealing method is to use high temperature glue to tightly adhere the vacuum bag to the surface of the forming mold. The single-sided high temperature glue is preferably four layers of tape, and the width of the tape layer directly connected to the layer is 1 / 3-1 / 4 of the tape width. After the tape and the vacuum bag are tightly adhered, a pressure plate is required to apply pressure to the adhesion to ensure reliable adhesion; vacuum is drawn to make the pressure in the bag -0.02--0.06MPA. The purpose of vacuuming is to position and initially fix the plate.

[0059] S5: Cover the upper surface of the first vacuum bag with a layer of breathable felt, then place the blank holder determined in S3 on the second layer of breathable felt corresponding to the original plate, then seal the blank holder, the plate as a whole and the mold surface with a second vacuum bag, and evacuate the outside of the tank to apply the blank holder force.

[0060] Among them, when the second layer of bags is evacuated, the pressure inside the second layer of vacuum bags is the difference between the external atmospheric pressure and the required blank holding force (when the blank holding force is constant, it is a constant force; when the blank holding force is a variable value, the pressure difference can be changed with the program through program settings). When the second layer is vacuum sealed, the single-sided high-temperature adhesive is preferably a three-layer tape, and the width of the tape layer directly connected to the layer is 1 / 3-1 / 4 of the tape width. After the tape is tightly bonded to the vacuum bag, a pressure plate is required to apply pressure to the bonding point to ensure reliable bonding. The reason for the second layer of sealing is to ensure the sealing of the forming process so that the component is evenly stressed during creep aging; secondly, to ensure the pressure of the blank holding ring.

[0061] S6: After creep aging in the tank, heat preservation and loading, the target component is obtained.

[0062] Among them, the aging temperature, creep loading pressure, aging time and creep loading rate of the creep aging forming of the component are determined by means of finite element simulation. The aging temperature range is 140℃-190℃, the creep loading pressure is 1.5-2.0MPA, and the aging time is 6-12h.

[0063] This embodiment solves the problem that the pressure of the conventional blank holder ring is difficult to be applied hydraulically in the autoclave. By forming a pressure difference between the external environment and the vacuum bag, a blank holder force can be applied to the blank holder ring in the autoclave. The applied blank holder force is uniform and can be changed with the program, thereby achieving the purpose of suppressing wrinkling of the bottom of the box. The method of this embodiment can be used to achieve creep aging precision forming of tank bottom components.

[0064] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0065] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for suppressing wrinkling of thin-walled components of tank bottom by creep aging forming, characterized in that: The method comprises: Obtain original plate parameters and target component parameters; Performing finite element simulation using the original sheet material parameters and the target component parameters to simulate the creep aging forming process of the original sheet material and obtain a high wrinkling risk area during the creep aging forming process of the original sheet material; Obtaining the stress-strain state change of the high wrinkling risk area; determining the shape of the edge holding device, the corresponding placement area of ​​the edge holding device on the original plate, and the edge pressure to be applied by the edge holding device according to the stress-strain state change of the high wrinkling risk area; After cleaning the original plate, wrap it with a layer of breathable felt and place it on the forming mold. Use a first layer of vacuum bag to seal it and perform vacuum treatment outside the autoclave to position and fix the original plate and the forming mold. A layer of air-permeable felt is covered on the upper surface of the first vacuum bag, and the edge pressing device is placed on the second air-permeable felt corresponding to the corresponding placement area, sealed with a second vacuum bag, and vacuumed outside the autoclave to apply the edge pressure to the edge pressing device; Control the creep aging forming process in the autoclave, and obtain the target component after creep aging forming after heat preservation and load holding; Among them, a second layer of vacuum bag is used for sealing, including: The second vacuum bag is tightly bonded to the edge holding device, the original plate and the surface of the forming mold by using high temperature glue; the high temperature glue is a three-layer tape, the tape layers are directly connected to each other, and the width between the layers is between 1 / 3 and 1 / 4 of the tape width; After the adhesive tape is tightly bonded to the second layer of vacuum bag, a pressure plate is used to apply pressure to the bonded portion to ensure reliable bonding.

2. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 1, characterized in that: The original plate parameters include: the diameter, thickness and material of the original plate; the target component parameters include target forming depth and forming curvature; wherein, when the target component is a spherical structure, the forming curvature is a single curvature; when the target component is an ellipsoidal structure, the forming curvature is the semi-major axis length and semi-minor axis length of the ellipsoid.

3. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 1, characterized in that: Determine the edge pressure to be applied by the edge clamping device, including: The edge pressure to be applied by the edge holding device is calculated in a uniformly distributed load or concentrated force manner; the edge pressure is a constant force or a force that varies with the forming process.

4. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 1, characterized in that: The shape of the edge holding device includes a circular ring shape and a circular ring block shape. Determining the shape of the edge holding device includes: Determine the inner diameter, outer diameter and thickness of the edge clamping device; wherein, the thickness of the edge clamping device is 3 to 10 times the thickness of the original plate; the outer diameter of the edge clamping device is half the diameter of the original plate, increased by 0 to 10 mm, and the inner diameter of the edge clamping device is determined by the forming curvature of the original plate.

5. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 4, characterized in that: When the thickness of the original plate is less than 1 mm, the thickness of the edge pressing device is 5 times the thickness of the original plate.

6. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 1, characterized in that: The original plate and the forming mold are sealed using a first layer of vacuum bag, comprising: The first vacuum bag is tightly bonded to the surface of the forming mold by using high temperature adhesive; the high temperature adhesive is a four-layer adhesive tape, the layers of the adhesive tape are directly connected to each other, and the width between the layers is between 1 / 3 and 1 / 4 of the width of the adhesive tape; After the adhesive tape is tightly adhered to the first layer of vacuum bag, a pressure plate is used to apply pressure to the adhered portion to ensure reliable adhesion.

7. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 1, characterized in that: Use the first vacuum bag to seal and perform vacuum treatment outside the autoclave, including: The autoclave is subjected to a vacuum treatment so that the pressure inside the first vacuum bag is between -0.02 and 0.06 MPa.

8. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 1, characterized in that: Use a second vacuum bag for sealing and evacuate outside the autoclave, including: The autoclave is subjected to a vacuum treatment so that the pressure inside the second vacuum bag is equal to the difference between the external atmospheric pressure and the side pressure.

9. The method for suppressing wrinkling of thin-walled tank bottom components by creep aging forming according to claim 8, characterized in that: The autoclave is subjected to a vacuum treatment so that the pressure inside the second vacuum bag is the difference between the external atmospheric pressure and the side pressure, including: When the side pressure is constant, a vacuum treatment is performed outside the autoclave to constantly control the pressure inside the second vacuum bag to be the difference between the external atmospheric pressure and the side pressure; When the side pressure is a variable force, a vacuum treatment is performed outside the autoclave to dynamically control the pressure inside the second layer of vacuum bag to be the difference between the external atmospheric pressure and the side pressure.

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