Thin-walled curved surface shell formed from a multi-cone preform and method for manufacturing the same

Abstract

A semi-elliptical, semi-toroidal or toroidal shell includes an annular metal plate wall longitudinally segmented such that it includes a plurality of annular wall segments. Each of the plurality of annular wall segments is joined to an adjacent wall segment by respective latitudinal wall welds. Also disclosed are a tank including the shell, a means of transport including the shell, a multi-conical preform used to manufacture the shell, a method of assembling the preform, and a method of manufacturing the shell using the preform.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 363,867, filed on April 29, 2022; U.S. Provisional Patent Application No. 63 / 367,004, filed on June 24, 2022; and U.S. Provisional Patent Application No. 63 / 384,175, filed on November 17, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure generally relates to welded metal parts having thin - walled curved surfaces and methods of manufacturing the same. More specifically, the present disclosure relates to shells formed from welded metal sheet parts (e.g., semi - elliptical shells, semi - toroidal shells, toroidal shells, etc.), tanks including the shells, transportation means including the shells, multi - conical preforms used to manufacture the shells, methods of assembling the multi - conical preforms, and methods of manufacturing the shells using the multi - conical preforms.

Background Art

[0003] Reusability, such as in rockets and aircraft, has long been the "ultimate goal" of rocketry due to the potential for significant cost - benefits. The ability to recover and reuse all rocket stages of a multi - stage rocket system (e.g., the lower and upper rockets of a two - stage rocket system) remains an important technological gap yet to be solved by this industry. The reusability of the upper rocket of a multi - stage rocket system is particularly difficult due to the harsh re - entry environment and the performance - adverse conditions associated with increasing the structural mass required to withstand the re - entry environment and guide the transportation means to the exact landing location. The upper rocket is typically constructed with minimal structure and complexity because any mass addition in the second stage results in a 1:1 reduction in payload capacity. Thus, reusing the upper rocket requires significant additional functionality while requiring minimal mass addition.

[0004] Efforts to achieve reusability such as that of an aircraft for a rocket have given rise to a demand for a new generation of high-performance parts with large and complex shapes. Specifically, many of the important structural parts of a rocket, including fuel tanks, nose cones at the front end of the rocket, etc., require a new generation of large lightweight parts with thin-walled curved surfaces. Several techniques are known for manufacturing such parts from alloys or other materials that are difficult to deform. Such techniques include (1) forming several smaller parts and then welding them together to form a large part, (2) performing metal forming (e.g., spinning, stamping, forging, etc.) to form a large part as a seamless one-piece part, and (3) additively manufacturing (e.g., 3D printing) a large part as a seamless one-piece part. These techniques may require machine tools (e.g., dies, machinery, etc.) that can be prohibitively large and / or costly, especially for new entrants into the industry.

[0005] To manufacture large parts with thin-walled curved surfaces without the need for dies or other large and / or expensive machine tools, fluid pressure forming techniques (e.g., hydroforming, cryogenic forming, etc.) have been developed. Fluid pressure forming generally involves the use of a fluid medium (e.g., water, oil, gas, liquefied gas, etc.) to apply a load and deform a workpiece. In some cases, the use of a die is partially or completely eliminated by providing a preform that at least partially defines a cavity into which the fluid medium is introduced. The pressure of the fluid medium within the cavity is increased in a controlled manner until the preform plastically deforms and expands to form a shell having the desired shape.

[0006] It is known to use fluid pressure forming technology to manufacture large spherical shells and ellipsoidal shells. For example, FIGS. 1 to 4 show some steps in the manufacture of a large ellipsoidal shell 310 (FIGS. 3 to 4) from a preform 216 (FIGS. 1 to 2) using fluid pressure forming. Referring to FIGS. 1 and 2, the preform 216 is formed from a plurality of metal sheet parts welded to each other. Specifically, the preform 216 includes a dome-shaped cap 218, a dome-shaped base 219, and an annular wall 220 extending therebetween. It should be noted that the wall 220 is divided in the latitude direction such that it includes a plurality of wall gore 226 each joined to an adjacent wall gore 226 by respective longitudinal welds 246. The cap 218, the base 219, and the wall 229 are shaped such that the preform 216 is polygonal. The cap 218, the base 219, and the wall 220 are metal sheet parts that are assembled and welded to each other after being formed by roll bending or otherwise to form the preform 216. The preform 216 defines a closed internal cavity into which fluid 249 (such as water) is injected via a pump 251, a hose 253, and an opening 254 disposed with reference to the cap 218. The pressure of the fluid medium within the preform cavity is raised in a controlled manner until the cap 218, the base 219, and the wall 220 plastically deform, bulge, and form a shell 310 (FIGS. 3 and 4) having the desired ellipsoidal shape. As a result of the plastic deformation and bulging, the respective radii r x2 , r z2 (see FIG. 3) along the major axis and minor axis 336, 354 of the shell 310 are larger than the corresponding radii r x1 , r z1 (see FIG. 1) of the preform 216.

[0007] Fluid pressure forming techniques such as those shown in FIGS. 1-4 can be advantageous in that they avoid the need for dies and other large and expensive machine tools. However, there may be problems associated with such techniques. For example, it may be difficult to accurately and reproducibly cut and bend the wall gore 226 into the required shape, and given the curvature of their edges, it can be time-consuming and difficult to accurately weld the wall gore 226 to each other.

[0008] In the context of a spherical shell, it is known to use cylindrical wall sections and upper and lower frustoconical wall sections instead of wall gores such as those in FIGS. 1 and 2. For example, FIGS. 5-7 show some steps in the manufacture of a large spherical shell 510 (FIG. 7) from a preform 416 (FIGS. 5 and 6) having a disc-shaped cap 418, a disc-shaped base 419, and an annular wall 420 extending therebetween. The cap 418, the base 419, and the wall 420 are metal sheet parts that are formed and then assembled and welded together to form the preform 416. The wall 420 is divided in the latitudinal direction such that it includes a plurality of wall sections 426, 428, 430 that are each joined to adjacent wall sections by respective latitudinal (e.g., circumferential) welds 432, 434. The sections of the wall 420 include an upper frustoconical wall section 426, a lower frustoconical wall section 430, and a cylindrical wall section 428 extending therebetween. The preform 416 defines a closed cavity into which a fluid 449 (e.g., water) is injected via a pump 451, a hose 453, and an opening 454 disposed in the cap 418. The pressure of the fluid medium is increased in a controlled manner until the cap 418, the base 419, and the wall 420 plastically deform and expand to form a shell 510 (FIG. 7) having the desired spherical shape. The plastic deformation and expansion give the shell 510 a smooth, curved spherical shape and an internal cavity that is larger than that of the preform 416. It should be noted that the radius r x2 (see FIG. 7) of the shell 510 is larger than the maximum radius r x1 (see FIG. 6) of the preform 416.

[0009] Referring to FIGS. 5 and 6, the use of walls 420 segmented in the longitudinal direction and in particular of frustoconical and cylindrical wall segments 426, 428, 430 is advantageous in that it enables the preform 416 to be manufactured in a more easily reproducible manner, faster and more accurately than preforms using conventional gore-shaped wall segments (see FIGS. 1-2). However, hitherto such techniques have been limited to use with preforms for spherical shells. This is because plastic deformation and bulging occurring during hydroforming are expected to cause unsightly and unstable deformations (such as wrinkles) in shells having any non-spherical shape (such as ellipsoids, semi-ellipsoids, toroids, semi-toroids, etc.). The prior art particularly teaches avoiding the use of such techniques involving preforms of large non-spherical shells, among other reasons, due to the difficulty of controlling the concentricity of the wall segments.

[0010] Another advantage of the hydroforming process is that plastic deformation of the sheet metal workpiece can achieve work hardening while maintaining the characteristics of the workpiece. For example, a few percent deformation of an austenitic stainless steel workpiece reduces the wall thickness of the workpiece while at the same time providing a significant homogeneous increase in yield strength. Plastic deformation transforms the austenite structure of the steel into martensite, which is much stronger and less ductile.

[0011] It is known that the rate of work hardening (such as austenite-martensite transformation) can be improved by exposing the workpiece to low temperatures during plastic deformation. Cryogenic stretching (or cryogenic forming) uses liquid nitrogen as a medium to extremely reduce the temperature of the workpiece during work hardening (for example, reducing the temperature to about -195° Celsius). However, the use of liquid nitrogen is costly and may introduce logistical complexities into the manufacturing process. Cold stretching (or cold warm forming) is a technique similar in principle to cryogenic stretching, but with water as the cooling medium instead of liquid nitrogen. Cold stretching is less expensive and less complex than cryogenic stretching, but the resulting work hardening is inferior to cryogenic stretching because the temperature is not as low. SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

[0012] Aspects of the present invention are directed to the above and other problems.

Means for Solving the Problems

[0013] According to one aspect of the present invention, a semi-elliptical shell includes a cap, an annular wall, and a latitudinal cap weld that joins the cap to the wall. The cap and the wall are sheet metal parts. The wall is longitudinally segmented to include a plurality of annular wall segments. Each of the plurality of annular wall segments is joined to an adjacent wall segment by its respective latitudinal wall joint.

[0014] According to another aspect of the present invention, a tank includes a semi-elliptical shell, the shell including a cap, an annular wall, and a latitudinal cap joint that joins the cap to the wall. The cap and the wall are sheet metal parts. The wall is longitudinally segmented to include a plurality of annular wall segments. Each of the plurality of annular wall segments is joined to an adjacent wall segment by its respective latitudinal wall joint.

[0015] According to another aspect of the present invention, a transport means includes a semi-elliptical shell, the shell including a cap, an annular wall, and a latitudinal cap joint that joins the cap to the wall. The cap and the wall are sheet metal parts. The wall is longitudinally segmented to include a plurality of annular wall segments. Each of the plurality of annular wall segments is joined to an adjacent wall segment by its respective latitudinal wall joint.

[0016] According to another aspect of the present invention, a multi - conical preform used for manufacturing a semi - ellipsoidal shell. The preform includes a preform cap, a multi - conical preform wall, and a first latitudinal preform weld that joins the preform cap to the preform wall. The preform cap and the preform wall are metal sheet parts. The preform wall is longitudinally segmented to include a plurality of annular preform wall segments. Each of the plurality of annular preform wall segments is joined to an adjacent preform wall segment by its respective latitudinal preform wall joint.

[0017] According to another aspect of the present invention, a method for manufacturing a semi - ellipsoidal shell includes providing the above - described multi - conical preform and performing a first fluid pressure forming step in which the inner surface of the preform is exposed to a reinforcing pressure that at least work - hardens the preform cap and the preform wall.

[0018] According to another aspect of the present invention, a method for assembling a multi - conical preform includes providing first and second preform wall segments, each in the form of a frustum - shaped metal sheet part, where the first preform wall segment has an upper - edge alignment mark arranged based on the upper edge of the first preform wall segment, and the second preform wall segment has a lower - edge alignment mark arranged based on the lower edge of the second preform wall segment; fixing the position of the first preform wall segment with respect to the second preform wall segment such that the upper - edge alignment mark of the first preform wall segment is aligned with the lower - edge alignment mark of the second preform wall segment; and joining the upper edge of the first preform wall segment to the lower edge of the second preform wall segment via a first latitudinal weld.

[0019] According to another aspect of the present invention, a semi - toroidal or toroidal shell includes a plurality of annular wall segments and a plurality of latitudinal wall welds. Each of the plurality of annular wall segments is joined to an adjacent wall segment by its respective latitudinal wall weld. Each of the annular wall segments is a metal sheet part.

[0020] According to another aspect of the present invention, a multi-conical preform used to manufacture a semi-toroidal or toroidal shell includes a metal plate preform wall. The preform wall is longitudinally segmented to include a plurality of annular preform wall segments. Each of the plurality of annular preform wall segments is joined to an adjacent preform wall segment by a respective latitudinal preform wall joint.

[0021] In addition to or instead of one or more of the above features, a further aspect of the present invention can include one or more of the following features individually or in combination. - The plurality of annular wall segments includes at least an upper wall segment, a lower wall segment, and a first latitudinal wall weld disposed therebetween. - The upper wall segment is joined to a cap via a latitudinal cap weld, and the lower wall segment defines the maximum radius of the shell in the direction of a second semi-axis perpendicular to the first semi-axis. - The plurality of annular wall segments includes at least one intermediate wall segment disposed between the upper wall segment and the lower wall segment. - Each of the plurality of annular wall segments has the respective shape of a frustum of an ellipsoid. - The upper wall segment has a first thickness, and the lower wall segment has a second thickness different from the first thickness. - The upper wall segment has a first thickness, and the lower wall segment has a second thickness the same as the first thickness. - The upper wall segment has a first thickness, and the lower wall segment has a second thickness, and the first thickness and the second thickness have different magnitudes. - The upper wall segment has a first hardness, and the lower wall segment has a second hardness different from the first hardness. - Each of the plurality of annular wall segments includes at least one longitudinal weld. - The plurality of annular wall segments includes at least a first wall segment latitudinally segmented into a plurality of sub-segments, and each of the plurality of sub-segments is joined to an adjacent sub-segment by a respective longitudinal weld. - The shell has a D / t ratio greater than 500, where D is the maximum diameter of the shell and t is the thickness of at least one of the cap and the wall. - The cap and the wall are stainless steel sheet metal parts. - The cap and the wall are martensitic stainless steel sheet metal parts. - The cap and the wall are strain-hardened sheet metal parts. - The cap is dome-shaped. - The cap and the wall are coaxially aligned with respect to the first semi-axis of the shell. - The tank includes an opening through which a fluid medium flows between the outside of the tank and the internal cavity defined by the tank through the bottom. - The semi-elliptical shell included in the tank is a first semi-elliptical shell, and the tank further includes a second semi-elliptical shell joined to the first semi-elliptical shell to give the tank an elliptical shape. - The tank further includes a non-elliptical shell joined to the semi-elliptical shell. - The non-elliptical shell included in the tank is a hemispherical shell. - The transportation means is a rocket. - The preform cap is dome-shaped. - The preform cap is at least substantially flat. - Each of the plurality of annular preform wall sections has the shape of a frustum of a cone. - The method further includes a second fluid pressure forming step in which the inner surface of the preform is plastically deformed and expanded to form a semi-elliptical shell and is exposed to a design pressure. - The method further includes a load reduction step performed between the first fluid pressure forming step and the second fluid pressure forming step, during which the pressure applied to the inner surface of the preform is at least partially reduced. - The method further includes exposing the preform to a low temperature in at least one of the first fluid pressure forming step and the second fluid pressure forming step. - Plastic deformation and bulging occurring during the second hydroforming step cause wrinkles to form in at least one of the preform dome and the preform wall, and the second hydroforming step includes exposing the inner surface of the preform to a design pressure for a predetermined period after the wrinkles are formed. - The positioning step includes connecting the upper edge of the first preform wall section to the lower edge of the second preform wall section via a plurality of tack welds. - The joining step includes joining the entire upper edge of the first preform wall section to the lower edge of the second preform wall section via a first circumferential weld. - The first circumferential weld is provided by a laser welder. - The joining step includes rotating the first and second preform wall sections on a rotating table while the fixed welder provides the first circumferential joint. - The method of assembling the multi-conical preform further includes cutting a plurality of preform wall partial sections from a metal plate and welding the plurality of preform wall partial sections to each other to form the first preform wall section. - The method of assembling the multi-conical preform further includes marking an upper edge alignment mark at a predetermined position on the metal plate before the step of cutting a plurality of preform wall partial sections from the metal plate. - The step of cutting a plurality of preform wall partial sections from the metal plate and the step of marking an upper edge alignment mark at a predetermined position on the metal plate are performed using the same laser cutter.

[0022] The above and other aspects of the present invention will become apparent in light of the drawings and the detailed description set forth below.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Figure 30

Figure 31

Figure 32

Figure 33

Figure 34

Figure 35

Figure 36

Figure 37

Figure 38

Figure 39

Figure 40

Figure 41

Mode for Carrying Out the Invention

[0024] The present disclosure relates to a shell 10 (see FIGS. 8, 9, 33, 34) formed from a welded metal plate part, a tank 12 (e.g., an internal pressure vessel) (see FIGS. 11 - 13) including at least one shell 10, a transport means 14 (see FIG. 14) including at least one shell 10, a multi - conical pre - form 16 (see FIGS. 18 and 19) used to manufacture at least one shell 10, a method of assembling the multi - conical pre - form 16 (see FIGS. 20 - 32), and a method of manufacturing at least one shell 10 using the pre - form 16 (see FIG. 32).

[0025] The shell 10 can have various shapes. In one embodiment (see FIGS. 8 and 9), the shell 10 has a semi-elliptical shape. In other embodiments (see FIG. 33), the shell 10 has a semi-toroidal or toroidal shape. In still other embodiments, the shell 10 can have another shape defined by a surface of revolution.

[0026] Referring to FIG. 8, in an embodiment where the shell 10 has a semi-elliptical shape, the shell 10 includes a cap 18, an annular wall 20, and a latitudinal cap weld 22 that joins the cap 18 to the wall 20. The cap 18 and the wall 20 are metal sheet parts (e.g., stretch-hardened metal sheet parts) having respective shapes formed by a fluid pressure forming process described later in part. The wall 20 is longitudinally segmented such that it includes a plurality of annular wall segments 26, 28, 30, each joined to an adjacent wall segment by respective latitudinal wall welds 32, 34. Specifically, the wall 20 includes at least one upper wall segment 26, a lower wall segment 30, and a first latitudinal weld 32 disposed therebetween. The upper wall segment 26 is the portion of the wall 20 joined to the cap 18 via the latitudinal cap weld 22. In the illustrated embodiment, the lower wall segment 30 defines the maximum radius r of the shell in the direction of a second semi-axis 36 (e.g., major semi-axis) perpendicular to the first semi-axis 24 x thereof.

[0027] Referring to FIGS. 8 and 9, in the illustrated embodiment, the cap 18 and the wall 20 of the shell 10 are shaped such that their respective outer surfaces meet to define the semi-elliptical shape of the shell 10. Referring to FIG. 9, the shell 10 also defines an internal cavity 38 having a corresponding semi-elliptical shape. The internal cavity 38 is defined by the respective inner surfaces of the cap 18 and the wall 20. In the illustrated embodiment, the shell 10 is a thin-walled monocoque structure. In other embodiments, the shell 10 is a semi-monocoque structure having one or more stiffening elements disposed with respect to the cap 18 and / or the wall 20.

[0028] In an embodiment where the shell 10 has a semi - ellipsoidal shape, the shell 10 can be configured in a variety of different ways. For example, the shape of the shell 10 can be a flattened semi - ellipsoid (i.e., a semi - ellipsoid formed by rotating a semi - ellipse having a semi - minor axis dimension and a semi - major axis dimension about its semi - minor axis), a prolate semi - ellipsoid (i.e., an ellipsoid formed by rotating a semi - ellipse having a semi - minor axis dimension and a semi - major axis dimension about its semi - major axis), or a triaxial semi - ellipsoid (i.e., a semi - ellipsoid having different dimensions along all three semi - axes).

[0029] For example, in the embodiments shown in FIGS. 8 and 9, the semi - ellipsoidal shell 10 has radii r x r y that are equal to each other and a radius r z that is larger along the first semi - axis 24. The cap 18 and the wall 20 are coaxially aligned with respect to the first semi - axis 24 (e.g., the short semi - axis) of the semi - ellipsoidal shell 10. The shell 10 is axisymmetric with respect to the first semi - axis 24 and thus has a flattened semi - ellipsoidal shape.

[0030] In other embodiments where the shell 10 has a semi - ellipsoidal shape, the shell 10 has radii r x r y that are equal to each other but a radius r z that is smaller along the first semi - axis 24. In such an embodiment, the shell 10 is axisymmetric with respect to the first semi - axis 24 and thus has a prolate semi - ellipsoidal shape.

[0031] In still other embodiments where the shell 10 has a semi - ellipsoidal shape, the shell 10 has radii r x r y r z that are all different relative to each other along the first, second, and third semi - axes 24, 36, 40. In such an embodiment, the shell 10 is not axisymmetric with respect to any of the semi - axes 24, 36, 40 and thus has a triaxial semi - ellipsoidal shape.

[0032] Referring back to FIG. 8, the cap 18 is, in part, a seamless one-piece component having a shape (such as a semi-elliptical shape, a dome shape, a disc shape, etc.) obtained by a hydroforming process described below. In the illustrated embodiment, the cap 18 defines a common apex of the semi-elliptical shell 10 and is axisymmetric with respect to the first semi-axis 24.

[0033] Continuing to refer to FIG. 8, the number of the annular wall sections 26, 28, 30 included in the wall 20 can be different. In one embodiment, the wall 20 includes only an upper wall section and lower wall sections 26, 30. In such an embodiment, a first circumferential wall weld 32 joins the upper wall section and the lower wall sections 26, 30 to each other. In other embodiments, including the illustrated embodiment of FIG. 8, the wall 20 includes at least one intermediate wall section 28 disposed between the upper wall section 26 and the lower wall section 30. In such an embodiment, a first circumferential wall weld 32 joins the upper wall section 26 to the adjacent intermediate wall section 28, and the wall 20 further includes at least one second circumferential wall weld 34 that joins at least one intermediate wall section 28 to the lower wall section 30.

[0034] Continuing to refer to FIG. 8, in the illustrated embodiment, the annular wall sections 26, 28, 30 each have the shape of a frustum of an ellipsoid. Referring to FIG. 9, each wall section 26, 28, 30 defines a part of the outer surface 42 of the shell 10, a part of the opposing inner surface 44 of the shell 10, and one or more thicknesses defined therebetween. In one embodiment, the respective thicknesses of the wall sections 26, 28, 30 are different from each other. In other embodiments, the respective thicknesses of the wall sections 26, 28, 30 are at least substantially the same relative to each other.

[0035] In certain embodiments, the respective thicknesses of the cap 18 and / or the wall 20 are selected based on a predetermined pressure contained within the shell 10 during its normal use. In certain embodiments, the shell 10 has a D / t ratio greater than 500, where D is the maximum diameter of the shell 10 and t is the thickness of the cap 18 and / or the wall 20 (e.g., the nominal thickness of the cap 18 and the wall 20). In other embodiments, the shell 10 has a D / t ratio greater than 1000. In still other embodiments, the shell 10 has a D / t ratio greater than 2000. In still other embodiments, the shell 10 has a D / t ratio greater than 3000. In certain embodiments, the maximum diameter D of the shell 10 has a size of about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 meters. In certain embodiments, the maximum diameter D of the shell 10 has a size greater than 10 meters.

[0036] Referring to FIG. 8, each of the annular wall sections 26, 28, 30 includes at least one longitudinal weld 46, 48, 50. In certain embodiments, one or more of the wall sections 26, 28, 30 are divided latitudinally into a plurality of subsections, each of which is joined to an adjacent subsection by its respective longitudinal weld 46, 48, 50. The number of subsections within a given wall section can vary, for example, from 2 subsections to 10 or more subsections. In the illustrated embodiment, the upper wall section 26 includes a plurality of subsections, each joined to an adjacent subsection by its respective longitudinal weld 46. Similarly, the intermediate wall section 28 includes a plurality of subsections, each joined to an adjacent subsection by its respective longitudinal weld 48. Finally, the lower wall section 30 includes a plurality of subsections, each joined to an adjacent subsection by its respective longitudinal weld 50.

[0037] Referring to FIGS. 8 and 10, in certain embodiments, the wall 20 includes at least one wrinkle 52 caused by plastic deformation and bulging that occurred during the fluid pressure forming process described below. In other embodiments, the wall 20 is at least substantially free of wrinkles. In such embodiments, the outer surface of the wall 20 has a smoothly curved shape that extends across its entire surface.

[0038] The metal plate components of the cap 18 and the wall 20 can be made of various types of materials (such as steel, aluminum, etc.). In the illustrated embodiment, the metal plate components are stainless steel (such as austenitic stainless steel, martensitic stainless steel). In certain embodiments, as a result of austenite-martensite work hardening that occurs during the hydroforming process described below, at least a portion of the metal plate components is martensitic stainless steel. In certain embodiments, the first component of the shell 10 has a first predetermined hardness and the second component of the shell 10 has a second predetermined hardness different from the first predetermined hardness. For example, in certain embodiments, the cap 18 is made of annealed stainless steel sheet metal and the wall 20 is made of hard stainless steel sheet metal (such as hard, semi-hard, etc.). In certain embodiments, the various sections 26, 28, 30 of the wall 20 are formed from different respective sheet metal materials having different predetermined hardnesses. The material of each wall section 26, 28, 30 can be selected based on the expected amount of plastic deformation and bulging that occurs during the fluid forming process. For example, in certain embodiments, the lower wall section 30 may be expected to undergo less plastic deformation and bulging than the upper wall section 26 and / or the cap 18. In such embodiments, the material of the sheet metal forming the lower wall section 30 may have a predetermined hardness lower than the hardness of the sheet metal material forming the upper wall section 26 and / or the cap 18. In other embodiments, the lower wall section 30 may be expected to undergo more plastic deformation and bulging than the upper wall section 26 and / or the cap 18. In such embodiments, the material of the sheet metal forming the lower wall section 30 may have a predetermined hardness higher than the hardness of the sheet metal material forming the upper wall section 26.

[0039] In one embodiment, the first component of the shell 10 has a first predetermined thickness, and the second component of the shell 10 has a second predetermined thickness different from the first predetermined thickness. The thickness of each of the wall sections 26, 28, 30 can be selected based on the expected amount of plastic change and swelling that occurs during the fluid forming process. For example, in one embodiment, the lower wall section 30 may be predicted to undergo less plastic change and swelling than the upper wall section 26 and / or the cap 18. In such an embodiment, the material of the metal sheet forming the lower wall section 30 may have a predetermined thickness thinner than the thickness of the metal sheet material forming the upper wall section 26. In other embodiments, the lower wall section 30 may be predicted to undergo more plastic deformation and swelling than the upper wall section 26 and / or the cap 18. In such an embodiment, the material of the metal sheet forming the lower wall section 30 may have a predetermined thickness thicker than the thickness of the metal sheet material forming the upper wall section 26.

[0040] In one embodiment, the shell 10 includes one or more additional components not shown in the drawings. For example, in one embodiment, the shell 10 includes at least one reinforcing component (e.g., ribs, cross beams, doubler plates, etc. arranged with reference to the welds).

[0041] Referring to FIGS. 11 - 13, the tank 12 of the present application includes at least one shell 10. In one embodiment, the tank 12 includes at least one port 54 through which a fluid medium flows between the exterior of the tank 12 and the internal cavity defined by the tank 12. The tank 12 can be configured for various purposes. For example, in one embodiment, the tank 12 is used to store fuel for a rocket or other means of transportation.

[0042] The tank 12 can have various different shapes and configurations. Referring to FIG. 11, in one embodiment, the tank 12 has an elliptical shape formed by two identical semi-elliptical shells 101, 102 joined to each other (e.g., via a circumferential weld). In another embodiment not shown in the drawings, the tank 12 is formed by two non-identical semi-elliptical shells 10 joined to each other. Referring to FIG. 12, in one embodiment, the tank 12 has a non-elliptical shape defined by a semi-elliptical shell 10 and a non-elliptical shell 56 joined to each other. For example, in the embodiment of FIG. 12, the tank 12 includes a semi-elliptical shell 10 joined to a hemispherical shell 10. Referring to FIG. 13, in one embodiment, the tank 12 includes more than two semi-elliptical shells 10. For example, in the embodiment of FIG. 13, the tank 12 includes identical first and second semi-elliptical shells 101, 102 joined to each other so as to define an elliptical upper chamber 58 having a first diameter D1 and a third semi-elliptical shell 103 that defines a lower chamber 60 having a second diameter D2 smaller than the first diameter D1. In the illustrated embodiment, the tank 12 includes a tank wall 62 extending between the upper chamber 58 and the lower chamber 60.

[0043] Referring to FIG. 14, the transportation means 14 of the present application includes at least one shell 10. In certain embodiments, the transportation means 14 is a rocket (e.g., a multi-stage rocket, a single-stage-to-orbit (SSTO) rocket, an upper-stage rocket, a booster rocket, etc.), a missile, a spacecraft, an aircraft, or other transportation means designed for movement (e.g., flight) in the atmosphere, suborbital, orbital, extraterrestrial, and / or space environments up to at least supersonic speeds (e.g., supersonic, hypersonic, reentry speeds, etc.). Referring to FIG. 14, in the illustrated embodiment, the transportation means 14 is a reusable second-stage rocket of a two-stage rocket system. The second-stage rocket is described in more detail in International Patent Application No. PCT / US22 / 71686 filed on April 13, 2022, and International Patent Application No. PCT / US22 / 71688 filed on April 13, 2022, which are assigned to the assignee of the present invention, and the entire contents of which are incorporated herein by reference. The transportation means 14 extends between a front end 64 and a rear end 66 opposite the front end 64. The transportation means 14 includes a payload housing 68 adjacent to the front end 64 and an engine 70 and a nozzle 72 adjacent to the rear end 66. The payload housing 68 is sealed by sidewalls 69 of the transportation means 14. In the illustrated embodiment, the transportation means 14 includes identical first and second semi-elliptical shells 101, 102 joined to each other to form a fuel tank 12 having inlets and outlets 54, 55. In certain embodiments, the transportation means 14 includes, in addition to or instead of the above, at least one shell 10 forming different components of the transportation means 14. For example, in the embodiment shown in FIG. 14, the semi-elliptical shell forms a nose 74 at the front end 64 of the transportation means 14, and another shell forms part of the nozzle 72 at the rear end 66 of the transportation means 14. Specifically, the nozzle 72 includes a central body sidewall and a central body base that form the respective outer surfaces of an actively cooled thermal insulator used during the initial reentry from the base of the transportation means 14, and the central body base includes a shell manufactured from a multi-conical preform using the techniques described herein.In certain embodiments, the shell forms the outer surface of the insulation material and is joined (e.g., by diffusion bonding, brazing, etc.) to one or more internal materials so as to form a structure (e.g., a sandwich structure) that defines fluid channels for actively dissipating heat from the external shell.

[0044] Referring to FIGS. 15-17, in certain embodiments, the internal cavity of tank 12 is at least partially defined by the walls of transport means 14 (e.g., a cylindrical side wall, a conical side wall). For example, in the embodiment shown in FIG. 15, transport means 14 is a rocket, and the internal cavity of tank 12 is defined by an upper semi-elliptical shell 101, a lower semi-elliptical shell 102, and a portion of a cylindrical rocket side wall 69 extending therebetween. In the embodiments shown in FIGS. 16 and 17, transport means 14 is a rocket, and the internal cavity of tank 12 is defined by an upper semi-elliptical shell 101, a lower semi-elliptical shell 102, and a portion of a conical rocket side wall 69 extending therebetween. In the embodiment of FIG. 16, the upper and lower semi-elliptical shells 101, 102 are configured such that they form the concave inner surface of tank 12. In the embodiment of FIG. 17, the lower semi-elliptical shell 102 forms the concave inner surface of tank 12, and the upper semi-elliptical shell 101 forms the convex inner surface of tank 12.

[0045] Referring to FIG. 18, an embodiment of the multi-conical preform 116 of the present application used to manufacture at least one shell 10 having a semi-elliptical shape includes a preform cap 118, a multi-conical preform wall 120, and a first latitudinal preform weld 122 that joins the preform cap 118 to the preform wall 120. The preform cap 118 and the preform wall 120 are metal sheet parts. The preform wall 120 is longitudinally segmented such that it includes a plurality of annular preform wall segments 126, 128, 130, each joined to an adjacent wall segment by respective latitudinal preform wall welds 132, 134. Specifically, the preform wall 120 includes at least an upper preform wall segment 126, a lower preform wall segment 130, and a first latitudinal preform wall weld 132 disposed therebetween. The upper preform wall segment 126 is the portion of the preform wall 120 joined to the preform cap 118 via the latitudinal preform-cap weld 122. In the illustrated embodiment, the lower preform wall segment 130 defines the maximum radius r of the preform 116 in the direction of a second semi-axis 136 (e.g., the major semi-axis) perpendicular to the first semi-axis 124 x thereof.

[0046] Continuing to refer to FIG. 18, in the illustrated embodiment, the preform cap 118 is an integral, seamless part having at least a substantially flat disk shape. The preform cap 118 and the preform wall 120 are coaxially aligned with respect to the first semi-axis 124 (e.g., the minor semi-axis) of the preform 116, and the preform cap 118 is axially symmetric with respect to the first semi-axis 124. In other embodiments, the preform cap 118 has a semi-elliptical shape, a dome shape, or other shape.

[0047] The number of preform wall sections 126, 128, 130 included in the preform wall 120 can be different, similar to how the number of wall sections 26, 28, 30 of the wall 20 of the shell 10 can be different. Each of the preform wall sections 126, 128, 130 has the shape of a frustum of a respective cone. In certain embodiments, the preform wall sections 126, 128, 130 define respective angles α1, α2, α3 that are different relative to each other. In certain embodiments, the respective thicknesses of the preform wall sections 126, 128, 130 are different from each other. In certain embodiments, the respective thicknesses of the preform cap 118 and / or the preform wall 120 are selected to achieve a specific ratio relative to the maximum diameter of the preform 116. In certain embodiments, the preform 116 has a D / t ratio greater than 500, where D is the maximum diameter of the preform 116 and t is the thickness of the cap 118 and / or the preform wall 120 (e.g., the nominal thickness of the preform cap 118 and the preform wall 120). In other embodiments, the preform 116 has a D / t ratio greater than 1000. In still other embodiments, the preform 116 has a D / t ratio greater than 2000. In still other embodiments, the preform 116 has a D / t ratio greater than 3000.

[0048] Continuing to refer to FIG. 18, each preform wall section 126, 128, 130 includes at least one longitudinal weld 146, 148, 149. In certain embodiments, one or more of the preform wall sections 126, 128, 130 are latitudinally segmented into a plurality of subsections, each of which is joined to an adjacent preform subsection by a respective preform longitudinal weld 146, 148, 149. For example, in FIG. 18, the lower preform wall section 130 is latitudinally segmented into eight subsections 178. The number of subsections in a given preform wall section can vary, for example, from two subsections to ten or more subsections.

[0049] Referring to FIG. 20, the method of the present application for assembling the preform 116 includes providing at least first and second preform wall sections 130, 128, each in the form of a frustoconical metal sheet part, positioning the first preform wall section 130 relative to the second preform wall section 128 (e.g., by a tack weld), and joining the upper edge of the first preform wall section 130 to the lower edge of the second preform wall section 128 via a first circumferential weld 134. In some embodiments, the first and second preform wall sections 130, 128 include respective alignment marks 111, 113, and the positioning step includes positioning the first preform wall section 130 relative to the second preform wall section 128 such that the upper edge alignment mark 111 of the first preform wall section 130 is aligned with the lower edge alignment mark 113 of the second preform wall section 128. In some embodiments, one or more additional frustoconical preform wall sections 126, 127 and / or a preform cap 118 are similarly positioned and joined to the first and second preform wall sections 130, 128.

[0050] Referring to FIG. 20, in the illustrated embodiment, the lower preform wall section 130 is positioned with respect to the first intermediate preform wall section 128 such that the upper edge alignment marks 111 of the lower preform wall section 130 are aligned with the lower edge alignment marks 113 of the first intermediate preform wall section 128. That is, each upper edge alignment mark 111 of the lower preform wall section 130 is aligned with a corresponding lower edge alignment mark 113 of the first intermediate preform wall section 128. Next, the upper edge of the lower preform wall section 130 is joined to the lower edge of the first intermediate preform wall section 128 via the first latitude direction weld 134. Referring to FIG. 21, next, the first intermediate preform wall section 128 is positioned with respect to the second intermediate preform wall section 127 such that the upper edge alignment marks 115 of the first intermediate preform wall section 128 are aligned with the lower edge alignment marks 117 of the second intermediate preform wall section 127. Next, the upper edge of the first intermediate preform wall section 128 is joined to the lower edge of the second intermediate preform wall section 127 via the second latitude direction weld 133. Referring to FIG. 22, next, the second intermediate preform wall section 127 is positioned with respect to the upper preform wall section 126 such that the upper edge alignment marks 119 of the second intermediate preform wall section 127 are aligned with the lower edge alignment marks 121 of the upper preform wall section 126. Next, the upper edge of the second intermediate preform wall section 127 is joined to the lower edge of the upper preform wall section 126 via the third latitude direction weld 132. Next, the preform cap 118 is connected to the upper preform wall section 126 via the fourth latitude direction weld 131. In the illustrated embodiment, the preform wall sections are positioned with respect to each other by a plurality of tack welds, and the latitude direction welds 131, 132, 133, 134 are formed by a laser welder that remains fixed while the preform wall sections are rotated about the first preform semi-axis 124 by a rotary table.

[0051] Referring to FIGS. 23 - 28, in one embodiment, the step of providing at least first and second preform wall segments includes forming the preform wall segments from a plurality of sub - segments. Referring to FIG. 23, in the illustrated embodiment, a metal plate 176 is provided from which a plurality of sub - segments 178 of the lower preform wall segment 130 are cut out. Referring to FIG. 24, the metal plate 176 has opposing planes 180, 182 and a thickness 184 defined therebetween. Referring to FIGS. 25 and 26, the sub - segments 178 are positioned relative to each other (FIG. 25) and are welded to each other at their respective side edges to form the preform wall segment 130 (FIG. 26). Referring to FIG. 27, the preform wall segment 130 has upper and lower edges 186, 188 that extend to respective faces perpendicular to the first preform semi - axis 124. An angle α3 is defined between the radially outer surface 190 and the surface defined by the lower edge 188 of the preform wall segment 130. Referring to FIG. 28, the thickness defined between the radially outer surface 190 and the radially inner surface 192 of the preform wall segment 130 corresponds to the thickness 184 of the metal plate 176 (see FIG. 23) from which the sub - segments 178 of the preform wall segment 130 were cut. The steps described above can be repeated for one or more of the other preform wall segments 126, 127, 128 included in the preform 116. Each metal plate used to form the components of the preform 116 can have different materials, hardnesses, thicknesses, and / or other properties relative to each other. In other embodiments, one or more of the preform wall segments may consist of a single metal plate component formed by welding opposing ends to each other to form a conical piece by a single longitudinal weld.

[0052] In certain embodiments where the preform wall segment includes alignment marks, the alignment marks are applied to the preform wall segment and / or sub-segments thereof before such parts are cut out from a metal sheet plate. For example, in FIG. 23, the dashed lines indicate the locations where eight sub-segments 178 of the lower preform wall segment 130 are cut out from the metal sheet plate 176. FIG. 23 shows that a lower edge alignment mark 109 and an upper edge alignment mark 111 are applied to the metal sheet plate 176 before the sub-segments 178 are cut out therefrom. In some embodiments, including the embodiment of the figure, at least the preform wall segment is configured such that all sub-segments of the preform wall segment, including the location of the alignment marks thereon, are identical to each other. For example, referring to FIG. 23, the eight sub-segments 178 cut out from the metal sheet plate 176 are all identical to each other, including the respective locations of the alignment marks on each sub-segment 178. This configuration simplifies the manufacture and assembly of the preform 116.

[0053] The alignment marks can be configured in various ways. Referring to FIGS. 27 and 28, in the illustrated embodiment, the alignment marks 109, 111 are shallow linear etchings provided at predetermined locations on the radially outer surface of the preform wall segment. The use of linear alignment marks can be advantageous in that when the corresponding alignment marks are aligned with each other, they appear to be clearly on the same line. Each alignment mark provides a visual indication of a predetermined alignment position on the latitude direction (e.g., circumferential direction) edge of the preform wall segment. In the illustrated embodiment, when the preform 116 is assembled, the predetermined alignment positions spaced along the latitude direction edges of each preform wall segment are positioned in a plane perpendicular to the first preform semi-axis 124. The spacing of the alignment marks along the latitude direction edges of each preform wall segment can be different.

[0054] As shown in FIGS. 29 to 31, each alignment mark has a depth D (FIG. 30), a width W (FIG. 30), and a length L (FIG. 31). The respective sizes of the depth D, width W, and length L can be selected such that the alignment mark 113 is easily visible for alignment purposes, but weakens the component only to an ignorable extent (even if weakened). The width W of the alignment mark can affect the alignment tolerance. In one embodiment, the width W of the alignment mark can be selected such that the alignment tolerance is within the thickness of the tack weld applied in the step of fixing the preform wall sections relative to each other.

[0055] In the embodiment of FIGS. 29 to 31, the width W is about 0.01 inch (0.0254 cm) (for example, about 254 μm). In the embodiment of FIG. 31, the respective lengths L of the alignment marks 111, 113 111 , L 113 are of a length such that the alignment mark extends outside the section 123 (hereinafter "heat-affected section 123") that is affected by heat while the alignment mark joins the upper edge of the lower preform wall section 130 to the lower edge of the first intermediate preform wall section 128 via the first latitude direction weld 134. In other embodiments, the respective lengths L of the alignment marks 111, 113 111 , L 113is the length in which the alignment mark does not extend outside the heat-affected section 123. In other embodiments, the alignment mark is configured in a different manner. For example, in other embodiments, the alignment mark is disposed on the radially inner surface of the preform wall section rather than on the radially outer surface, the alignment mark has a shape other than a straight line, and / or the alignment mark is disposed on the preform wall section rather than being etched within the preform wall section. In embodiments where the alignment mark is disposed (rather than etched) on the preform wall section, the alignment mark has a height H rather than a depth D, and the alignment mark may be removed (e.g., by grinding) after the respective preform wall sections are positioned and joined relative to each other. In certain embodiments, a single device (e.g., a laser cutter) is used for both etching the alignment mark in the metal plate and cutting out the preform wall portion section from the metal plate. In such embodiments, the device can be operated at a first setting (e.g., relatively lower power) when etching the alignment mark and at a second setting (e.g., relatively higher power) when cutting out the preform wall portion section from the metal plate.

[0056] The method of the present application for assembling the preform is advantageous in that it avoids the need for costly machine tools and alignment jigs commonly used in similar applications, particularly in the aerospace industry. The method of the present application enables the preform wall sections to be positioned relative to each other using only vice-grips and tack welds. The individual preform wall sections have relatively low rigidity due to their thin sheet metal material. However, the rigidity increases dramatically after a few tack welds during the positioning step. The increased rigidity and the alignment marks enable two technicians, on opposite sides of the preform wall section in the circumferential direction, to simultaneously perform the operation of providing a tack weld at the joint between two corresponding alignment marks. The use of alignment marks further ensures that the continuous joint defined by the adjacent latitudinal edges of adjacent preform wall sections defines a constant arc length with respect to the first preform semi-axis 124. Without such alignment marks, the arc length may vary from section to section. This can cause unwanted bubbles in the preform, which may be difficult to correct after they are detected.

[0057] Referring to FIG. 32, in one embodiment, two multi-conical portions 194, 196 are joined to each other to form a preform 116 that defines a closed internal cavity. In the embodiment of FIG. 31, the portions 194, 196 of the preform 116 are substantially the same as the preform 116 of FIG. 11. In other embodiments not shown in the drawings, the preform 116 is formed from two multi-conical portions 194, 196 having different respective shapes.

[0058] The method of the present application for manufacturing the shell 10 using the preform 116 includes a first fluid pressure forming step in which the inner surface of the preform 116 (e.g., the surface defining the closed internal cavity) is exposed to a strengthening pressure that work hardens at least the preform cap 118 and the preform wall 120. Referring to FIG. 32, for example, the strengthening pressure can be applied by a fluid 149 injected into the internal cavity of the preform 116 via a pump 151, a hose 153, and an orifice 154 disposed in the preform cap 118. The method further includes a second fluid pressure forming step in which the inner surface of the preform 116 is exposed to a design pressure that plastically deforms and expands the preform 116 to form the shell 10. Although the first and second fluid pressure forming steps are described as separate steps, in certain embodiments, these are performed directly in succession and can be characterized as first and second sub-steps of a single fluid pressure forming step instead of the above. In certain embodiments, a load relief step is performed between the first fluid pressure forming step and the second fluid pressure forming step. During the load relief step, the pressure applied to the inner surface of the preform 116 is reduced or completely removed. In certain embodiments, one or more of these steps are performed while the preform is exposed to low temperature using known cold drawing and / or cryogenic techniques. In certain embodiments, the plastic deformation and swelling that occur during the second fluid pressure forming step form wrinkles in one or both of the preform cap 118 and the preform wall 120. In certain embodiments, the second fluid pressure forming step includes exposing the inner surface of the preform 116 to the design pressure for a predetermined period after the wrinkles are formed. Each pressure applied during the first and second pressure forming steps is not limited to any particular pressure magnitude and can vary depending on one or more characteristics of the sheet metal part (e.g., thickness, material, etc.) and / or one or more performance requirements of the resulting shell 10 or tank 12 (e.g., a predetermined pressure that is normally contained within the shell 10 or tank 12 during its use). In certain embodiments, each pressure is greater than 20 PSI (about 137 kPa). In certain embodiments, each pressure is less than 500 PSI (about 3447 kPa).In some embodiments, each pressure ranges between 20 PSI and 500 PSI. In other embodiments, each pressure exceeds 500 PSI.

[0059] Referring to FIGS. 33 and 34, in embodiments where the shell 10 has a semi-toroidal or toroidal shape, the shell 10 includes an annular wall 20 that defines an internal cavity 38 having a corresponding semi-toroidal or toroidal shape. The wall 20 is longitudinally segmented such that it includes a plurality of annular wall segments 26, each joined to an adjacent wall segment by a respective latitudinal wall weld 32. Referring to FIG. 34, in the illustrated embodiment, the wall 20 includes an upper radial outer wall segment 261, a radial outer wall segment 262, a lower radial outer wall segment 263, a lower radial inner wall segment 264, a radial inner wall segment 265, and an upper radial inner wall segment 266. In the illustrated embodiment, the wall 20 defines an oval shape in a cross-section parallel to the axis of symmetry 24 of the shell 10. In other embodiments not shown in the drawings, the wall 20 of the semi-toroidal or toroidal shell 10 defines a circular shape or other shape. The semi-toroidal or toroidal shell 10 omits the cap included in the semi-elliptical shell 10 (see FIGS. 8 and 9), but can include the same features as the semi-elliptical shell 10 in other respects and can be manufactured using the same or substantially similar techniques.

[0060] Referring to FIGS. 35-37, in an embodiment where a multi-conical preform 116 is used to manufacture at least one shell having a semi-toroidal or toroidal shape, the preform 116 includes a multi-conical preform wall 120 that is longitudinally segmented such that it includes a plurality of annular preform wall segments 126, each joined to an adjacent preform wall segment by a respective latitudinal preform wall weld 132. Referring to FIGS. 36 and 37, in the illustrated embodiment, the preform wall 120 includes an upper radially outer preform wall segment 1261, a radially outer preform side wall segment 1262, a lower radially outer preform wall segment 1263, a lower radially inner preform wall segment 1264, a radially inner preform side wall segment 1265, and an upper radially inner preform wall segment 1266. In the illustrated embodiment, the preform wall 120 defines a hexagonal shape in a cross-section parallel to the axis of symmetry 124 of the preform 116. Referring to FIGS. 38-41, in other embodiments, the preform wall 120 has an outer profile having a triangular shape (FIG. 38), a square shape (FIG. 39), a pentagonal shape (FIG. 40), and other polygonal shapes (FIG. 40) in a cross-section parallel to the axis of symmetry 124 of the preform 116. The preform 116 for manufacturing the semi-toroidal or toroidal shell 10 omits the preform cap 118 (see FIG. 22), but may include the same or substantially similar features as the preform for manufacturing the semi-elliptical shell in other respects. Also, the preform 116 for manufacturing the semi-toroidal or toroidal shell 10 can be assembled using the same or substantially similar techniques as the preform for manufacturing the semi-elliptical shell.

[0061] Although several embodiments have been disclosed, those skilled in the art will recognize that aspects of the invention include many additional embodiments. Accordingly, aspects of the invention are not limited except as defined in the appended claims and their equivalents. Those skilled in the art will also recognize that modifications and variations are possible without departing from the true scope of the disclosure. For example, in some cases, one or more features disclosed in connection with one embodiment can be used alone or in combination with one or more features of one or more other embodiments.

Claims

1. It is a semi-ellipsoidal shell, The cap and The ring wall and The cap includes a latitudinal cap weld that joins the cap to the wall, The cap and the wall are metal plate parts. The wall is divided in the longitudinal direction so as to include a plurality of annular wall sections, A semi-ellipsoidal shell in which the aforementioned multiple annular wall sections are joined to adjacent wall sections by latitudinal wall welds.

2. The semi-ellipsoidal shell according to claim 1, wherein the plurality of annular wall sections include at least an upper wall section, a lower wall section, and a first latitudinal wall weld disposed between them.

3. The cap and the wall are coaxially aligned with respect to the first semi-axis of the shell, The semi-ellipsoidal shell according to claim 2, wherein the upper wall section is joined to the cap via the latitudinal cap weld, and the lower wall section defines the maximum radius of the shell in the direction of a second semi-axis perpendicular to the first semi-axis.

4. The semi-ellipsoidal shell according to claim 3, wherein the plurality of annular wall sections include at least one intermediate wall section disposed between the upper wall section and the lower wall section.

5. The semi-ellipsoidal shell according to claim 3, wherein each of the plurality of annular wall divisions has the shape of a frustum of an ellipsoid.

6. The semi-ellipsoidal shell according to claim 3, wherein the upper wall section has a first thickness and the lower wall section has a second thickness different from the first thickness.

7. The semi-ellipsoidal shell according to claim 3, wherein the upper wall section has a first thickness and the lower wall section has a second thickness equal to the first thickness.

8. The semi-ellipsoidal shell according to claim 3, wherein the upper wall section has a first thickness, the lower wall section has a second thickness, and the first thickness and the second thickness are of different sizes.

9. The semi-ellipsoidal shell according to claim 3, wherein the upper wall section has a first hardness and the lower wall section has a second hardness different from the first hardness.

10. The semi-ellipsoidal shell according to claim 3, wherein each of the plurality of annular wall sections includes at least one longitudinal weld.

11. The semi-ellipsoidal shell according to claim 1, wherein the plurality of annular wall divisions include at least a first wall division divided latitudinally into a plurality of subdivisions, and each of the plurality of subdivisions is joined to an adjacent subdivision by its respective longitude weld.

12. The semi-ellipsoidal shell according to claim 1, wherein the shell has a D / t ratio greater than 500, where D is the maximum diameter of the shell and t is the thickness of at least one of the cap and the wall.

13. The semi-ellipsoidal shell according to claim 1, wherein the cap and the wall are stainless steel metal plate parts.

14. The semi-ellipsoidal shell according to claim 1, wherein the cap and the wall are made of martensitic stainless steel metal plate parts.

15. The semi-ellipsoidal shell according to claim 1, wherein the cap and the wall are stretch-hardened metal plate components.

16. The semi-ellipsoidal shell according to claim 1, wherein the cap is dome-shaped.

17. The semi-ellipsoidal shell according to claim 1, wherein the cap and the wall are coaxially aligned with respect to the first semi-axis of the shell.

18. The cap and the wall are coaxially aligned with respect to the first semi-axis of the shell, The cap defines the first radius of the shell in the direction of the first semi-axis, The wall defines the second radius of the shell in the direction of a second semi-axis perpendicular to the first semi-axis, The semi-ellipsoidal shell according to claim 1, wherein the second radius is larger than the first radius.

19. The semi-ellipsoidal shell according to claim 18, wherein the semi-ellipsoidal shell is a flattened semi-ellipsoidal shell.

20. The semi-ellipsoidal shell according to claim 18, wherein the inner surface of the cap defines the first radius of the shell, and the inner surface of the wall defines the second radius of the shell.

21. A tank including a semi-ellipsoidal shell, The aforementioned semi-ellipsoidal shell, The cap and The ring wall and The cap includes a latitudinal cap weld that joins the cap to the wall, The cap and the wall are metal plate components that are coaxially aligned with respect to the first semi-axis of the shell. The wall is divided in the longitudinal direction so as to include a plurality of annular wall sections, A tank in which each of the aforementioned plurality of annular wall sections is joined to an adjacent wall section by its respective latitudinal wall weld.

22. The tank according to claim 21, further comprising a port through which a fluid medium flows between the outside of the tank and an internal cavity defined by the tank.

23. The tank according to claim 21, wherein the semi-ellipsoidal shell is a first semi-ellipsoidal shell, and the tank further includes a second semi-ellipsoidal shell joined to the first semi-ellipsoidal shell so as to give the tank an ellipsoidal shape.

24. The tank according to claim 21, further comprising a non-ellipsoidal shell joined to the semi-ellipsoidal shell.

25. The tank according to claim 24, wherein the non-ellipsoidal shell is a hemispherical shell.

26. The tank according to claim 21, wherein the semi-ellipsoidal shell is the semi-ellipsoidal shell according to any one of claims 2 to 20.

27. A transport means including a semi-ellipsoidal shell, wherein the semi-ellipsoidal shell is The cap and The ring wall and The cap includes a latitudinal cap weld that joins the cap to the wall, The cap and the wall are metal plate parts. The wall is divided in the longitudinal direction so as to include a plurality of annular wall sections, A transport means wherein each of the plurality of annular wall sections is joined to an adjacent wall section by its respective latitudinal wall weld.

28. The transport means according to claim 27, wherein the transport means is a rocket.

29. The transport means according to claim 27, wherein the semi-ellipsoidal shell is the semi-ellipsoidal shell according to any one of claims 2 to 20.

30. A polyconical preform used to manufacture a semi-ellipsoidal shell, Preformed cap and, Multiconical preform walls and The preform cap is joined to the preform wall by a first latitudinal preform weld, The preform cap and the preform wall are metal plate components. The aforementioned preform wall is divided in the longitudinal direction so as to include a plurality of annular preform wall sections, A polyconical preform in which each of the plurality of annular preform wall sections is joined to an adjacent preform wall section by a latitudinal preform wall weld.

31. The multi-conical preform according to claim 30, wherein the preform cap is dome-shaped.

32. The polyconical preform according to claim 30, wherein the preform cap is at least substantially flat.

33. The multi-conical preform according to claim 30, wherein each of the plurality of annular preform wall sections has the shape of a frustum of a cone.

34. A method for manufacturing a semi-ellipsoidal shell using a polyconical preform, Preformed cap and, Multiconical preform walls and A step of providing a polyconical preform having a first latitudinal preform weld for joining the preform cap to the preform wall, The preform cap and the preform wall are metal plate components. The preform wall is divided in the longitudinal direction so as to include a plurality of annular preform wall sections, The step of providing a polyconical preform, wherein each of the plurality of annular preform wall sections is joined to an adjacent preform wall section by a latitudinal preform wall weld, A method comprising the step of performing a first fluid pressure molding in which the inner surface of the preform is subjected to a strengthening pressure that work-hardens at least the preform cap and the preform wall.

35. The method according to claim 34, further comprising the step of performing a second fluid pressure forming step, in which the inner surface of the preform is subjected to a design pressure that causes plastic deformation and bulging of the preform to form the semi-ellipsoidal shell.

36. The method according to claim 35, further comprising a load reduction step performed between the first fluid pressure forming step and the second fluid pressure forming step, wherein during the load reduction step, the pressure applied to the inner surface of the preform is at least partially reduced.

37. The method according to claim 35, further comprising the step of exposing the preform to a low temperature in at least one of the first fluid pressure forming step and the second fluid pressure forming step.

38. The method according to claim 35, wherein the plastic deformation and bulging occurring during the second fluid pressure forming step cause wrinkles to form in at least one of the preform dome and the preform wall, and the second fluid pressure forming step includes exposing the inner surface of the preform to the design pressure for a predetermined period after the wrinkles have been formed.

39. A method for assembling a multi-cone preform, A step of providing first and second preform wall sections, each in the form of a frustoconical metal plate component, wherein the first preform wall section has an upper edge alignment mark positioned relative to the upper edge of the first preform wall section, and the second preform wall section has a lower edge alignment mark positioned relative to the lower edge of the second preform wall section, The first preform wall section is positioned and fixed relative to the second preform wall section so that the upper edge alignment mark of the first preform wall section is aligned with the lower edge alignment mark of the second preform wall section. A method comprising the step of joining the upper edge of the first preform wall section to the lower edge of the second preform wall section via a first latitudinal weld.

40. The method according to claim 39, wherein the position fixing step includes connecting the upper edge of the first preform wall section to the lower edge of the second preform wall section via a plurality of tack welds.

41. The method according to claim 39, wherein the joining step includes joining the entire upper edge of the first preform wall section to the lower edge of the second preform wall section via the first latitudinal weld.

42. The method according to claim 41, wherein the first latitudinal weld is provided by a laser welding machine.

43. The method according to claim 39, wherein the joining step includes rotating the first and second preform wall sections on a rotary table while a fixed welding machine provides the first latitudinal weld.

44. The steps include cutting out multiple preform wall sections from a metal plate, The method according to claim 39, further comprising the step of welding the plurality of preform wall portions to each other to form the first preform wall portion.

45. The method according to claim 44, further comprising the step of marking the upper edge alignment marks at predetermined positions on the metal plate before cutting out the plurality of preform wall sections from the metal plate.

46. The method according to claim 45, wherein the step of cutting out the plurality of preform wall portions from the metal plate and the step of marking the upper edge alignment marks at predetermined positions on the metal plate are performed using the same laser cutter.

47. A semi-toroidal or toroidal shell, Multiple annular wall sections, Including multiple latitudinal wall welds, Each of the aforementioned plurality of annular wall sections is joined to an adjacent wall section by its respective latitudinal wall weld, A semi-toroidal or toroidal shell in which each of the aforementioned annular wall sections is a metal plate component.

48. A polyconical preform used to manufacture semi-toroidal or toroidal shells, Includes metal sheet preform walls, The aforementioned preform wall is divided in the longitudinal direction so as to include a plurality of annular preform wall sections, A polyconical preform in which each of the plurality of annular preform wall sections is joined to an adjacent preform wall section by a latitudinal preform wall weld.

Images