Double-sided non-equal-curvature corrugated pressure-resistant shell and rolling forming equipment and method

Abstract

The invention discloses a double-sided non-equal-curvature corrugated pressure-resistant shell and a rolling forming device and method, and belongs to the technical field of deep sea equipment pressure-resistant structure design and metal plastic forming. The double-sided non-equal-curvature corrugated pressure-resistant shell comprises a corrugated shell body, the inner surface and the outer surface of the corrugated shell body are each provided with a circumferential corrugated shape, and the wave crest area is a negative Gaussian curvature shell section; the wave trough area is a positive Gaussian curvature shell section, the inner surface corrugation amplitude is larger than the outer surface corrugation amplitude, the thickness of the corrugated shell body periodically and continuously changes in the axial direction, no thickness sudden change exists, the thickness at the wave crest is the maximum value, and the thickness at the wave trough is the minimum value. The problem that the corrugated pressure-resistant shell cracks and loses efficacy before reaching the critical load can be solved, the buckling mode is improved, the buckling load is improved, and the light weight of the shell is promoted.

Description

Technical Field

[0001] This invention relates to the field of pressure-resistant structure design for deep-sea equipment and metal plastic forming technology, and in particular to a double-sided non-uniform curvature corrugated pressure-resistant shell and its rolling forming equipment and method. Background Technology

[0002] Stealth and survivability are core performance indicators for underwater weapons and deep-sea operational equipment, while the maximum diving depth directly determines the equipment's tactical maneuverability and operational range. When the strength of pressure materials reaches its limit, optimizing the design of the pressure hull structure to improve buckling performance is a key approach to overcoming diving depth limitations.

[0003] In existing technologies, solutions for improving the pressure resistance of cylindrical shells mainly fall into two categories: one is to weld stiffening ribs inside a traditional smooth cylindrical shell. While this solution can improve compressive strength, it suffers from drawbacks such as large structural weight, complex manufacturing processes, and stress concentration in the welded area, severely limiting the mobility and endurance of equipment; the other is to adopt a corrugated structure design. The corrugated morphology can significantly improve the buckling performance of the cylindrical shell, but existing corrugated pressure shells still have many technical shortcomings.

[0004] Patent document CN115488153B discloses a circumferentially corrugated cylindrical pressure shell with a smooth outer surface and circumferential corrugations on the inner surface, with its thickness varying regularly along the axial direction. However, when this structure buckles under hydrostatic pressure, the Gaussian curvature in the trough region becomes negative due to insufficient stiffness, making it highly susceptible to premature cracking. Moreover, cracking may occur before the critical load, and the measured failure load is not the true critical load, seriously affecting the structural reliability. English document DOI:10.1016 / j.oceaneng.2023.115963 verified this problem through hydrostatic pressure testing and pointed out that initial geometric defects further exacerbate the risk of cracking.

[0005] The English literature (DOI: 10.1016 / j.tws.2020.106988) investigated the buckling failure behavior of a uniformly thick circumferentially corrugated shell. It found that the corrugated joints (negative Gaussian curvature shell sections) are weak points for fracture failure, and the fracture risk increases significantly with increasing corrugation height. The core reason for this problem lies in the unreasonable matching between the corrugation morphology and the wall thickness distribution, resulting in an imbalance of mechanical equilibrium between the crests and troughs, forming a "short plank effect," leading to unsatisfactory buckling modes and ultimately premature failure.

[0006] In addition, the existing forming processes of corrugated pressure shells mostly rely on welding, stamping and other methods, which have problems such as metal flow line breakage, coarse grains and low forming accuracy. It is difficult to achieve the integration of structural design and manufacturing, which further limits the performance and engineering application of corrugated pressure shells.

[0007] Therefore, there is an urgent need to develop a corrugated pressure shell structure and manufacturing method that can improve buckling failure, balance lightweight and high pressure resistance, and achieve efficient integrated molding. Summary of the Invention

[0008] To address the fracture failure and manufacturing bottlenecks of existing cylindrical pressure shells, this invention provides a double-sided non-uniform curvature corrugated pressure shell, along with rolling forming equipment and methods. This solution addresses the cracking failure of corrugated pressure shells before reaching critical loads, improves buckling modes, enhances buckling load capacity, and promotes shell lightweighting.

[0009] The technical solution adopted by the present invention for a double-sided non-uniform curvature corrugated pressure shell and its rolling forming equipment and method is as follows:

[0010] A double-sided non-uniform curvature corrugated pressure shell includes a corrugated shell body. Both the inner and outer surfaces of the corrugated shell body are provided with circumferential corrugations. The crest regions are shell segments with negative Gaussian curvature, and the trough regions are shell segments with positive Gaussian curvature. The corrugation amplitude on the inner surface is greater than that on the outer surface. The thickness of the corrugated shell body changes periodically and continuously along the axial direction, with the maximum thickness at the crest and the minimum thickness at the trough.

[0011] A further improvement to the technical solution of this invention lies in that: the morphology of the inner and outer surfaces is controlled by trigonometric functions, and the control equation for the inner surface ripples is: The outer surface ripple control equation is: Then the geometric mid-surface equation of the corrugated shell body for:

[0012]

[0013] set up and Both are sine function curves, with function amplitudes of respectively and Half-cycle is And satisfy The thickness of the corrugated section, transformed into a rectangular section using the "peak-filling and valley-filling" method, is... The wall thickness at any point along the centerline on the geometric mid-surface of the corrugated shell body. for:

[0014]

[0015] The minimum wall thickness of the corrugated shell body is .

[0016] A further improvement of the technical solution of the present invention lies in that: the geometric mid-surface of the corrugated shell body has a varying axial curvature. and circumferential curvature Let the maximum radius of the outer surface of the corrugated shell be... Base circle radius It is the distance from the abscissa axis of the geometric surface equation to the centerline of the corrugated shell body, i.e. The axial curvature and circumferential curvature They are respectively:

[0017]

[0018] .

[0019] A further improvement to the technical solution of this invention lies in that: the volume of the corrugated shell body can be calculated using the "peak-filling" method, assuming the height of the corrugated shell body is... corrugated shell body volume It can be calculated using the following two equations:

[0020]

[0021] .

[0022] A double-sided non-uniform curvature corrugated pressure shell rolling forming equipment is used to roll the aforementioned corrugated pressure shell. It includes an inner corrugated roll, an axially closed outer corrugated roll, a clamping roll, and a tapered roll. The axially closed outer corrugated roll is an active rotating component used to drive the workpiece to rotate. The inner corrugated roll can make linear feed motion along the thinning direction of the workpiece. The clamping roll is used to adapt to the increase in the diameter of the workpiece and keep the workpiece stable. The tapered roll is used to flatten the end face of the workpiece and ensure continuous bite of the workpiece.

[0023] A method for rolling a double-sided non-uniform curvature corrugated pressure shell, using the above-mentioned equipment, with a rectangular cross-section cylindrical blank as the base material, the forming process is divided into a clamping and biting stage (Ⅰ), a local forming stage (Ⅱ), a global forming stage (Ⅲ), and a diameter expansion and thinning stage (Ⅳ); in the local forming stage, the contact area between the inner corrugated roll and the outer corrugated roll and the cylindrical blank is equal, but the reduction amount and the horizontal distance between the two contact endpoints are not equal.

[0024] A further improvement to the technical solution of this invention lies in: assuming the corrugation function curve of the inner corrugated roll is... The contact point with the inner surface of the cylindrical blank is , Let the corrugation function curve of the external corrugated roll be... The contact point with the outer surface of the cylindrical blank is , Then, the reduction of the inner corrugated roll and the outer corrugated roll , for:

[0025]

[0026]

[0027] in, , .

[0028] A further improvement to the technical solution of this invention lies in: axial constraint is applied during the rolling process, and the heights of both the billet and the corrugated shell body are... Let the number of corrugations on the roll be... The thickness of the cylindrical blank is The base circle radius of the cylindrical blank is Then the thickness of each stage and base circle radius for,

[0029] Local forming stage:

[0030]

[0031]

[0032] Global shaping stage:

[0033]

[0034]

[0035] The outer ripples have been fully formed. Given the known morphological parameters of the external corrugated roll, It is a constant value;

[0036] Diameter expansion and thinning stage:

[0037]

[0038]

[0039] Both the inner and outer corrugations have been formed. , , It is the feed speed of the inner corrugated roll. It refers to time, calculated from the moment the entire system is formed.

[0040] A further improvement to the technical solution of this invention lies in: establishing a difficulty evaluation standard for cross-sectional profile based on wavy morphology characteristics. The evaluation criteria satisfy any of the following formulas:

[0041]

[0042] .

[0043] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0044] This invention achieves dual reinforcement of local curvature and local thickness through a design of double-sided non-uniform amplitude synchronous periodic corrugations and matching curvature and thickness. The crest region is a shell segment with negative Gaussian curvature and the greatest thickness, which plays a major supporting role when resisting hydrostatic pressure; the trough region is a shell segment with positive Gaussian curvature and the smallest thickness, which meets the requirements of external pressure bearing and plastic deformation capacity, greatly improving the utilization rate of shell material and the strength-to-weight ratio, and solving the technical problems of premature fracture failure and unreasonable stiffness anisotropy of existing corrugated shells.

[0045] This invention employs rolling forming technology, utilizing the synergistic action of inner corrugated rolls, axially enclosed outer corrugated rolls, clamping rolls, and tapered rolls to achieve continuous plastic deformation of metal billets. During rolling, metal grains are refined, and metal flow lines remain intact, avoiding stress concentration and defects caused by welding processes. The staged forming strategy facilitates the gradual formation of the corrugated morphology, precisely controlling the thickness and radius changes at each stage through the principle of equal volume. Simultaneously, the axially enclosed outer corrugated roll design ensures the integrity of the outer corrugations, while the flat end face of the tapered rolls enables continuous engagement, improving forming efficiency and product quality. The corrugated shell body forming process of this invention eliminates the need for complex subsequent processing, enabling direct conversion of design solutions into products, shortening the R&D cycle, reducing manufacturing costs, and providing technical support for large-scale production. Attached Figure Description

[0046] Figure 1 This is a design process diagram of the double-sided non-uniform curvature corrugated pressure-resistant shell of the present invention;

[0047] Figure 2 This is a diagram showing the cross-section and geometric relationship of the corrugated shell body in the coordinate system of this invention;

[0048] Figure 3 This is a schematic diagram illustrating the "peak-shaving and valley-filling" principle of the present invention.

[0049] Figure 4 This is a diagram of the rolling forming equipment for the double-sided non-uniform curvature corrugated pressure shell of the present invention;

[0050] Figure 5 Cross-sectional views of different rolling forming stages of the present invention;

[0051] Figure 6 The evaluation standard diagram for the corrugated cross-section profile is full of difficulties;

[0052] Figure 7 Finite element analysis diagram of buckling of a double-sided non-uniform curvature corrugated pressure shell;

[0053] Figure 8 Finite element analysis diagram of the rolling process of a double-sided non-uniform curvature corrugated pressure shell.

[0054] In the attached diagram: 1. Conical roll; 2. Cylindrical blank; 3. Inner corrugated roll; 4. Clamping roll; 5. Outer corrugated roll. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention.

[0056] Example 1

[0057] This embodiment provides a double-sided non-uniform curvature corrugated pressure shell, the design concept of which includes both biomimetic design and topological design, such as... Figure 1 As shown. This embodiment includes a corrugated shell body. The inner and outer surfaces of the corrugated shell body are provided with circumferential corrugations of different amplitudes. The corrugation periods are equal and synchronous. The corrugations run circumferentially and are arranged axially. The corrugation amplitude on the inner surface is greater than that on the outer surface. The thickness is greatest at the crest, and the crest region is a negative Gaussian curvature shell segment, which can also be called a concave shell segment. The thickness is smallest at the trough, and the trough region is a positive Gaussian curvature shell segment, which can also be called a convex shell segment.

[0058] Based on the above description of the characteristics of the double-sided non-uniform curvature corrugated pressure shell, a global geometric model and coordinate system are constructed, such as... Figure 2 As shown. Assume the corrugation curves on the inner and outer surfaces of the corrugated shell are controlled by a sine function, and the corrugation equation for the inner surface is: The equation for the outer surface ripples is: Then the equation of the geometric surface for:

[0059]

[0060] The thickness of the corrugated shell body varies periodically along the central axis. and The function magnitudes are respectively and Half-cycle is The "peak-filling and valley-filling" method is used to segment and reorganize the inner and outer surface corrugations, which can be transformed into a rectangular cross-section, such as... Figure 3 As shown. Let the thickness of the rectangular cross-section be... In geometry, the wall thickness at any point along the centerline of a surface. for:

[0061]

[0062] exist Figure 2 middle, It can also be The thickness is expressed as the minimum thickness of the corrugated shell body along the centerline (at the trough). Considering the possibility of an unsolvable case for this structure, it should be guaranteed that... Therefore, the following geometric relationship holds:

[0063]

[0064] The corrugated shell body geometry provided in this embodiment has regularly varying axial and circumferential curvatures on its surfaces, such as... Figure 2 As shown. Let the maximum radius of the outer surface of the corrugated shell be... Base circle radius It is the distance from the abscissa axis of the geometric surface equation to the centerline of the corrugated shell body, i.e. Axial curvature of the mid-surface of the corrugated shell body geometry and circumferential curvature It can be represented as:

[0065]

[0066]

[0067] The corrugated shell body provided in this embodiment has corrugated morphology on its inner and outer surfaces that follows a certain periodic pattern, such as sinusoidal, semi-circular, or triangular. Regardless of the shape, the volume of the corrugated shell body can be calculated using the "peak-filling" method, such as... Figure 3 As shown. Let the height of the corrugated shell body be... The volume is It can be calculated using the following two equations.

[0068]

[0069] .

[0070] Example 2

[0071] Based on the structural characteristics of the corrugated shell described above, this embodiment provides a rolling forming method for a double-sided non-uniform curvature corrugated pressure shell, which can achieve integrated forming of the pressure shell. The technical solution includes two parts: rolling equipment and forming process. The rolling equipment includes, for example... Figure 4As shown, it includes a tapered roll 1, a cylindrical blank 2, an inner corrugated roll 3, a clamping roll 4, and an axially closed outer corrugated roll 5. The cylindrical blank 2 is a rectangular cross-section cylindrical section with the same length as the corrugated shell body. The outer corrugated roll actively rotates to drive the cylindrical blank 2, while the inner corrugated roll makes a linear feed motion in the thinning direction of the cylindrical blank 2. The clamping roll opens and closes as the diameter of the cylindrical blank 2 increases to maintain the stability of the rolled piece. The tapered roll is used to flatten the end face to ensure continuous biting of the rolled piece. Based on the formation process of the corrugation morphology and the radial growth motion of the shell, the rolling forming process of the corrugated shell body can be divided into: the clamping and biting stage (Ⅰ), the local forming stage (Ⅱ), the global forming stage (Ⅲ), and the diameter expansion and thinning stage (Ⅳ), as follows. Figure 5 As shown. The clamping and biting stage is for the smooth biting of the billet 2. This stage is short in duration, and the changes in corrugation morphology and billet diameter are negligible. The local forming stage refers to the stage where the outer and inner surface corrugations are formed simultaneously. The amplitude of the outer surface corrugations is smaller than that of the inner surface, and the outer surface corrugations are formed first. After this stage, the outer corrugations are fully formed, and the diameter increases. The global forming stage refers to the stage where, after the outer surface corrugations are formed, the rolls continue to feed, and the inner surface corrugations continue to form. In this stage, both the inner and outer surface corrugations are fully formed, and the diameter increases significantly. The diameter expansion and thinning stage refers to the stage where, after the corrugation morphology is complete, rolling continues to the predetermined target size. In this stage, only the diameter increases.

[0072] At the beginning of the local forming stage, the corrugations on both the inner and outer surfaces are not fully formed. The contact areas between the inner corrugated roll 3, the outer corrugated roll 5, and the billet 2 are equal, but the reduction and the horizontal distance between the contact endpoints are not equal. Let the corrugation function curve of the inner corrugated roll 3 be... The contact point with the inner surface of the cylindrical blank 2 is , Let the corrugation function curve of the external corrugated roll 5 be... The contact point with the outer surface of the cylindrical blank 2 is , ,like Figure 5 As shown. The reduction amount of the inner corrugated roll 3 and the outer corrugated roll 5. , They can be approximated by the following equations.

[0073]

[0074]

[0075] in, , .

[0076] The rate at which the radius grows varies at different forming stages. Axial constraints are applied during rolling, and the lengths of both the billet 2 and the corrugated shell body are... Let the number of corrugations on the roll be... The thickness of the cylindrical blank 2 is The base circle radius of the cylindrical blank is The thickness and base circle radius at a certain moment during the feeding process can be calculated using the equal volume method. Based on the above forming stages, this embodiment includes the following steps:

[0077] S1. Thickness at a certain moment during the local forming stage of the feeding process. The radius of the base circle at a certain moment It can be calculated using the following equation.

[0078]

[0079]

[0080] S2. Based on the local forming stage of S1, after the local forming stage is completed, the outer corrugations are fully formed, and the process enters the global forming stage. The thickness at a certain moment during the feeding process... The radius of the base circle at a certain moment It can be calculated using the following equation.

[0081]

[0082]

[0083] The outer ripples have been fully formed, so Given the known morphological parameters of the external corrugated roll, It is a constant value.

[0084] S3. Based on the global forming stage of S2, after the global forming stage is completed, both the inner and outer corrugations have been fully formed, and the stage of diameter expansion and thinning begins. The thickness at a certain moment during the feeding process is... The radius of the base circle at a certain moment It can be calculated using the following equation.

[0085]

[0086]

[0087] Both the inner and outer corrugations have been formed, so , , It is the feed speed of the inner corrugated roll. It refers to time, calculated from the moment the entire system is formed.

[0088] The corrugated shell body provided by this invention has full-size characteristics, and the corrugation morphology parameters are complex and diverse. There are multiple combinations of corrugation morphology parameters on the inner and outer surfaces. The rolling difficulty of corrugated shell bodies with different morphologies is also different. Based on its morphological characteristics, a cross-sectional profile difficulty evaluation standard is established. ,like Figure 6 As shown. The evaluation criteria can be calculated using the following two equations.

[0089]

[0090]

[0091] Figure 7 The deformation of the corrugated shell body after loading ae is shown, along with a comparison of two failure modes of the corrugated shell body, where a and e represent the circumferentially inward corrugated shell body and the uniformly thick wall corrugated shell body, respectively. and The figures represent the difference in corrugation height on the outer surface before and after loading. Assuming a uniform external load of 10 MPa, after loading, it was found that the troughs of corrugated shell body a exhibited reverse bowing, and the Gaussian curvature became negative. Corrugated shell body e underwent further deformation at the crests, with the Gaussian curvature remaining negative and gradually increasing. Corrugated shell bodies a and e were prone to fracture failure during buckling, while corrugated shell bodies b, c, and d exhibited good buckling performance, with the crests fully utilizing their supporting capacity and the troughs possessing good deformation capacity. Figure 7 The finite element displacement cloud diagrams in the diagram demonstrate the excellent load-bearing capacity of the double-sided non-uniform curvature corrugated pressure shell.

[0092] Figure 8 Finite element analysis results of the rolling process of a double-sided non-uniform curvature corrugated pressure shell are presented. In the local forming stage, the corrugation morphology is just beginning to form, and at this point, the forged penetration area is staggered along the width direction. As the feed rate gradually increases, the forged penetration area gradually becomes more uniform and symmetrical. The finite element results are basically consistent with the theoretical calculation results, verifying the feasibility of the corrugated shell body rolling process described in this invention.

[0093] In the above embodiments, a double-sided non-uniform curvature corrugated pressure shell and its rolling forming equipment and method are provided. This invention achieves dual reinforcement of local curvature and local thickness through the design of non-uniform amplitude synchronous corrugations, curvature, and thickness matching. The crest region is a shell segment with negative Gaussian curvature and the largest thickness, bearing the main supporting role; the trough region is a shell segment with positive Gaussian curvature and the smallest thickness, meeting the external pressure bearing requirements and plastic deformation capacity, greatly improving the shell material utilization rate and strength-to-weight ratio, and solving the technical problems of trough fracture failure and unreasonable stiffness anisotropy in existing corrugated shells. This invention adopts rolling forming technology, achieving continuous plastic deformation of the metal billet through the synergistic action of inner corrugated rolls, axially closed outer corrugated rolls, clamping rolls, and tapered rolls. During the rolling process, the metal grains are refined, and the metal flow lines remain intact, avoiding stress concentration and defects caused by welding processes; the staged forming strategy is beneficial to the gradual formation of the corrugated morphology, and the thickness and radius changes at each stage are precisely controlled through the principle of equal volume. Meanwhile, the axially enclosed external corrugated roll design ensures the integrity of the external corrugations, the clamping rolls ensure the stability of the rolled piece, and the flat end face of the tapered rolls enables continuous biting, improving forming efficiency and product quality. The corrugated shell body forming process of this invention does not require complex subsequent processing, realizing the direct conversion of design schemes into products, shortening the R&D cycle, reducing manufacturing costs, and providing technical support for large-scale production.

[0094] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. A double-sided non-uniform curvature corrugated pressure-resistant shell, comprising a corrugated shell body, characterized in that: Both the inner and outer surfaces of the corrugated shell body are provided with circumferential corrugations. The corrugation periods of the inner and outer surfaces are equal and synchronous. The crest region is a shell segment with negative Gaussian curvature, and the trough region is a shell segment with positive Gaussian curvature. The corrugation amplitude of the inner surface is greater than that of the outer surface. The thickness of the corrugated shell body changes periodically and continuously along the axial direction, with the maximum thickness at the crest and the minimum thickness at the trough.

2. The double-sided non-uniform curvature corrugated pressure-resistant shell according to claim 1, characterized in that, The corrugation morphology of the inner and outer surfaces is controlled by trigonometric functions. Let the control equation for the inner surface corrugation be: The outer surface ripple control equation is: Then the geometric mid-surface equation of the corrugated shell body is: ； set up and Both are sine function curves, with function amplitudes of respectively and Half-cycle is And satisfy The corrugated section is transformed into a rectangular section with a thickness of [thickness value missing] using the "peak-filling and valley-filling" method. The wall thickness at any point along the centerline on the geometric mid-surface of the corrugated shell body. for: ； The minimum wall thickness of the corrugated shell body is .

3. A double-sided non-uniform curvature corrugated pressure-resistant shell according to claim 2, characterized in that: The corrugated shell body has a varying axial curvature on its geometric mid-surface. and circumferential curvature Let the maximum radius of the outer surface of the corrugated shell be... Base circle radius It is the distance from the abscissa axis of the geometric surface equation to the centerline of the corrugated shell body, i.e. The axial curvature and circumferential curvature They are respectively: ； 。 4. A double-sided non-uniform curvature corrugated pressure-resistant shell according to claim 2, characterized in that, The volume of the corrugated shell body can be calculated using the "peak-filling" method. Let the height of the corrugated shell body be... corrugated shell body volume It can be calculated using the following two equations: ； 。 5. A rolling forming equipment for a double-sided non-uniform curvature corrugated pressure shell, characterized in that: The material is used for rolling the corrugated pressure shell according to any one of claims 1-4, including an inner corrugated roll (3), an axially closed outer corrugated roll (5), a clamping roll (4), and a tapered roll (1); wherein, the axially closed outer corrugated roll (5) is an active rotating component used to drive the workpiece to rotate, the inner corrugated roll (3) can make linear feed motion along the thinning direction of the workpiece, the clamping roll (4) is used to adapt to the increase in the diameter of the workpiece and keep the workpiece stable, and the tapered roll (1) is used to flatten the end face of the workpiece and ensure continuous biting of the workpiece.

6. A method for rolling a double-sided non-uniform curvature corrugated pressure shell, characterized in that: Using the equipment described in claim 5, with a rectangular cross-section cylindrical blank (2) as the base material, the forming process is divided into a clamping and biting stage (Ⅰ), a local forming stage (Ⅱ), a global forming stage (Ⅲ), and a diameter expansion and thinning stage (Ⅳ); in the local forming stage, the contact area between the inner corrugated roll (3) and the axially closed outer corrugated roll (5) and the cylindrical blank (2) is equal, while the reduction amount and the horizontal distance between the contact endpoints are not equal.

7. The rolling forming method for a double-sided non-uniform curvature corrugated pressure shell according to claim 6, characterized in that: Let the corrugation function curve of the inner corrugated roll (3) be... The contact point with the inner surface of the cylindrical blank (2) is , Let the corrugation function curve of the external corrugated roll (5) be... The contact point with the outer surface of the cylindrical blank (2) is , Then the reduction of the inner corrugated roll (3) and the outer corrugated roll (5) , for: ； ； in, , .

8. The rolling forming method for a double-sided non-uniform curvature corrugated pressure shell according to claim 6, characterized in that: During the rolling process, axial constraints are applied, and the heights of the billet (2) and the corrugated shell body are both... Let the number of corrugations on the roll be... The thickness of the cylindrical blank (2) is The base circle radius of the cylindrical blank (2) is Then the thickness of each stage and base circle radius for, Local forming stage: ； ； Global shaping stage: ； ； The outer ripples have been fully formed. Given the known morphological parameters of the external corrugated roll, It is a constant value; Diameter expansion and thinning stage: ； ； Both the inner and outer corrugations have been formed. , , It is the feed speed of the inner corrugated roll. It refers to time, calculated from the moment the entire system is formed.

9. A method for rolling a double-sided non-uniform curvature corrugated pressure shell according to claim 6, characterized in that: Establishing a cross-sectional profile evaluation standard based on wavy morphology characteristics is highly challenging. The evaluation criteria satisfy any of the following formulas: ； 。

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