An arc additive manufacturing method of an aluminum alloy thin-walled shell with longitudinal rib plate

Abstract

The application belongs to the technical field of additive manufacturing, and discloses an electric arc additive manufacturing method for an aluminum alloy thin-walled shell with longitudinal internal rib plates, which comprises the following steps: establishing a three-dimensional model of a component and setting a reference coordinate system; slicing all the longitudinal internal rib plates together with the shell; initializing each slice contour path; extracting the main shape path of the shell and each longitudinal internal rib plate; rearranging the main shape path of the shell and each longitudinal internal rib plate; planning the accumulation path according to the main shape path of each longitudinal internal rib plate; sequentially connecting the shell and all the planned longitudinal internal rib plate paths at the beginning and the end to form a final closed-loop accumulation path; and performing electric arc additive manufacturing according to the closed-loop accumulation path. Through the application, the number of arc breakages in the electric arc additive manufacturing process can be greatly reduced, and problems such as electric arc gun interference and shell melting through that occur when the shell is formed first and then the rib plates are accumulated in the shell can be effectively avoided, thereby significantly improving the component forming quality and efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of additive manufacturing, and more particularly, to an electric arc additive manufacturing method for an aluminum alloy thin-walled shell with longitudinal internal rib plates. BACKGROUND

[0002] Aluminum alloy thin-walled shell components are widely used in aerospace, automotive, petrochemical and other fields. Due to the system assembly and structural stability requirements, irregular longitudinal internal rib plates perpendicular to the end face and distributed along the generatrix of the shell are generally arranged on the inner wall of the components. Currently, the thin-walled shell components with longitudinal internal rib plates are mainly manufactured by casting and welding assembly. However, the casting process has the problems of coarse grains, easy to produce shrinkage and crack defects, uneven structure and composition, and poor mechanical properties. When welding the longitudinal internal rib plates on the inner wall of the shell, the welding torch is easy to interfere, the weldability is poor, and the uneven welding stress can cause deformation of the rib plate and the thin-walled shell, reducing the structural size precision of the component.

[0003] Some process schemes for manufacturing aluminum alloy thin-walled shells with longitudinal internal rib plates by electric arc additive process have been proposed in the prior art. Specifically, the electric arc additive manufacturing melts the metal wire by an electric arc heat source, and forms a three-dimensional metal component layer by layer according to the planned path. The small molten pool smelts and refines the grains, improves the component composition uniformity, avoids defects, and ensures the mechanical properties of the component. Based on the three-dimensional model, the component is formed layer by layer point by point and domain by domain, which ensures the structural size precision of the component and avoids the shortcomings of casting and welding methods. Therefore, it is an effective method for manufacturing aluminum alloy thin-walled shells with longitudinal internal rib plates.

[0004] However, the forming quality of the metal component by electric arc additive manufacturing depends largely on the established accumulation process method and strategy, and the solutions in the prior art cannot be well applied to the application object such as the thin-walled shell with longitudinal internal rib plate of aluminum alloy. More specifically, the thin-walled shell with longitudinal internal rib plate is composed of multiple irregular internal rib plates and shells, and is a typical multi-unit complex structure. The prior art usually adopts a zoned additive process method for such components, that is, the component is first zoned, and then each region is accumulated and formed one by one. For example, the early patents CN108971699A and CN110802302A retrieved disclose a zoned additive manufacturing method for typical multi-unit complex components such as large ship stern shaft support and multi-directional steel joint of high-rise building. The large ship stern shaft support is divided into three regions of stern shaft hub, horizontal arm and support arm, and is sequentially additive. The geometric shape of the slice for different regions is planned for accumulation path; the multi-directional steel joint is divided into a main pipe and multiple branch pipes and numbered, and then the main pipe is formed, and each branch pipe is sequentially formed in order. The layered slice of each pipe body is established on the basis of the formed pipe body. However, for the thin-walled shell with longitudinal internal rib plate, the shell is the main structure, and needs to be formed first after zoned additive. If the shell is accumulated and formed first, and then the electric arc gun is inserted into the shell to accumulate the longitudinal internal rib plate, the electric arc gun is easy to interfere and collide with the shell, causing accidents. At the same time, since the shell is a thin-walled structure, it is easy to be severely heated and cause melting when the longitudinal internal rib plate is accumulated thereon, reducing the manufacturing quality and component qualification rate.

[0005] Secondly, if the longitudinal internal rib plate and the shell are regarded as a whole, the process method of whole slicing and accumulation forming of the component can avoid the shortcomings of zoned additive, but the process method must adopt a suitable planning strategy for the accumulation path in each accumulation layer slice. For example, the early patent CN110834133A retrieved proposes an electric arc additive manufacturing path planning method without overlapping in the layer. The linear feature group is extracted from the slice of the large-thickness block component, the linear path is formed, the swing filling is used along the path to eliminate the inter-lane overlap, and the forming efficiency and quality are improved. However, the design of the path planning method is based on the cross-sectional shape of the large-thickness block, and cannot be applied to the thin-walled shell component. At the same time, the method is a global swing filling for solid slice, and the path needs to be divided into multiple segments that are not connected when filling the annular thin-walled slice of the shell, which greatly increases the number of arc extinguishing and reduces the forming quality.

[0006] For example, the retrieved early patent CN113695709A discloses a method for designing a tail blank of a space bearing structure electric arc fuse additive path planning. For the corner with concentrated stress distribution or the circular arc feature with small temperature gradient on the component model, a tail blank rib plate connected with the component main body is designed on the outside of the circular arc feature. By the ring-like distribution of the stacking path, the part of the path at the arc extinguishing point is crossed and placed on the rib plate, so that the component main body is free of arc extinguishing segments. However, the path planning method cannot be applied to thin-walled shell components with longitudinal internal rib plates. If all the arc extinguishing segments are placed on the longitudinal internal rib plates, the stacking defects on the rib plates will increase, the stress distribution will be uneven, and the size accuracy and mechanical properties of the formed part will be severely reduced.

[0007] In addition, the retrieved early patent CN111890061A proposes an electric arc additive manufacturing method for a transition end frame shell component with external rib plates. The rib plates are sliced together with the shell. Each slice has multiple stacking paths that are not connected. The inner and outer contours of the formed shell are stacked first, then the central axis path of the shell is stacked between the inner and outer contours, then the outer contour of the rib plate is stacked along the circumference of the shell, and finally the offset filling is performed within the outer contour of the rib plate. However, since the stacking paths are independent of each other, arc extinguishing must be repeated during stacking. The shell is extinguished at least twice, and each rib plate is extinguished at least four times. The number of arc interruptions is large, which causes stress concentration and deformation of the component. Meanwhile, the stacking defects at the interruption increase, which reduces the forming quality of the component. SUMMARY

[0008] To overcome the above defects or needs of the prior art, the purpose of the present application is to provide an electric arc additive manufacturing method for an aluminum alloy thin-walled shell with longitudinal internal rib plates. The strategy of slicing the longitudinal internal rib plates together with the shell along the axial direction of the component and forming them in one whole stack is adopted. The main shape contour path of the shell and each longitudinal internal rib plate in the slice is extracted, and the filling path within the contour is planned. Finally, the position point set of each path is rearranged in several times, so that the multiple independent paths in each slice are sequentially connected at the head and tail. The ring-shaped stack is formed in one whole stack. Accordingly, the number of arc interruptions in the electric arc additive manufacturing process can be greatly reduced, and the problems of arc gun interference and shell melting through when forming the shell first and then stacking the rib plate in the shell can be effectively avoided, which significantly improves the forming quality and efficiency of the component.

[0009] To achieve the above-mentioned purpose, according to the present application, an electric arc additive manufacturing method for an aluminum alloy thin-walled shell with longitudinal internal rib plates is provided, characterized in that the method comprises the following steps:

[0010] (a) modeling and setting up a reference coordinate system step

[0011] In this step, for the aluminum alloy thin-walled shell with longitudinal internal rib plates to be processed and manufactured, a corresponding component three-dimensional model is established, and a reference coordinate system containing XYZ three axes is set up;

[0012] (b) The whole shell and longitudinal rib plate slicing step

[0013] In this step, all the longitudinal rib plates are sliced together with the shell along the Z-axis direction, i.e. parallel to the direction of the shell axis, and the slice profile composed of the outer profile and the inner profile is obtained;

[0014] (c) The initialization step of the slice profile path

[0015] In this step, for the outer and inner profile paths corresponding to the outer and inner profiles respectively, the position point sets contained therein are respectively sorted according to the minimum value of the X-axis coordinate in the clockwise direction, thereby obtaining the initialized outer and inner profile paths;

[0016] (d) The main shape path extraction step

[0017] In this step, for the shell, the initialized outer profile path is inwardly offset by a certain distance, and a new outer profile is extracted, which is the main shape path of the shell;

[0018] For each longitudinal rib plate, the initialized inner profile path is outwardly offset by a corresponding distance, and the inner profile is extended to intersect with the new outer profile of the shell, and the non-closed region between the intersection points is the main shape path of each longitudinal rib plate;

[0019] (e) The main shape path rearrangement step

[0020] In this step, the main shape path of the shell is divided into multiple parts by the intersection points, and the multiple parts are arranged in the clockwise direction, and the main shape paths of each longitudinal rib plate are respectively closed in the clockwise direction, thereby completing the rearrangement of the main shape path;

[0021] (f) The filling path planning step of the longitudinal rib plate

[0022] In this step, the main shape paths of each longitudinal rib plate are taken out in the clockwise direction in turn, and the accumulation path planning is performed according to the main shape paths, thereby obtaining the accumulation path of each longitudinal rib plate;

[0023] (g) The closed loop accumulation path formation and electric arc additive manufacturing step

[0024] In this step, the main shape path of the shell after step (e) processing and the accumulation path of all longitudinal rib plates are connected head to tail in the clockwise direction, and the final closed loop accumulation path is obtained;

[0025] Based on the final closed loop accumulation path, each accumulation layer is formed once in the circumferential direction by using the electric arc additive manufacturing process, until the required aluminum alloy thin-walled shell with longitudinal rib plate is obtained.

[0026] As a further preferred, in step (b), the initial slice height is preferably set to 0.2mm-0.5mm; from the second slice, the slice height is preferably set to 70%-90% of the single pass deposited metal height.

[0027] As a further preferred, in step (d), for the shell, the initialized outer contour path is preferably offset inward by a distance of 1 / 2 of the shell thickness; for each longitudinal inner rib, the initialized inner contour path is preferably offset outward by a distance of 1 / 2 of the shell thickness, and the inner contour is extended to intersect the new outer contour of the shell.

[0028] As a further preferred, in step (f), for each longitudinal inner rib, the main shape path is preferably simultaneously subjected to single pass, offset and scan coordinated deposition path planning.

[0029] As a further preferred, in step (f), the single pass deposited metal width is preferably designed using the following formula: shell thickness + 2*single side machining allowance.

[0030] As a further preferred, in step (f), the single side machining allowance is preferably 1.5mm-3mm, and the overlap amount is preferably 25%-42% of the single pass deposited metal width.

[0031] As a further preferred, in step (g), the wire material and the substrate used in the electric arc additive manufacturing process are both aluminum alloys, the protective gas type is high-purity Ar, and the flow rate is preferably 20L / min-25L / min.

[0032] As a further preferred, in step (g), the following multiple sets of process windows are preferably used for manufacturing:

[0033] Process one: deposition current 150A-183A, deposition voltage 22V-24V, deposition speed 0.7mm / min-1.0mm / min;

[0034] Process two: deposition current 100A-136A, deposition voltage 20V-22V, deposition speed 0.5mm / min-0.8mm / min;

[0035] Process three: deposition current 180A-210A, deposition voltage 25V-26V, deposition speed 0.6mm / min-0.9mm / min.

[0036] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0037] (1) In this invention, the longitudinal inner stiffening plate and the shell are sliced ​​and the path is planned together, and the whole is stacked and formed. This avoids the problems that are easy to cause interference of the arc gun and excessive heat input leading to melting and penetration of the shell when the shell is formed first and then the arc gun is inserted into the shell to stack the longitudinal inner stiffening plate. This significantly improves the manufacturing efficiency and quality of the component.

[0038] (2) In this invention, the main shape path of the shell and the longitudinal inner stiffener is extracted first, and then the main shape path is filled and scanned to fill in a single way. The points of each path are connected end to end and rearranged in an orderly manner to achieve one-time circumferential stacking of each stacking layer, which greatly reduces the number of arc breaks, reduces stress concentration and deformation, avoids the generation of defects, and further improves the forming accuracy and mechanical properties of the component.

[0039] (3) In this invention, the thin-walled shell component with longitudinal inner stiffeners is manufactured by using electric arc additive manufacturing, which effectively avoids the problems of porosity, cracks, coarse grains and severe compositional segregation that are easy to occur during casting, as well as the problems of poor weldability and easy welding deformation that occur when welding and assembling longitudinal inner stiffeners. Attached Figure Description

[0040] Figure 1 This is a main process flow diagram showing the electric arc additive manufacturing method for a thin-walled aluminum alloy shell with longitudinal internal stiffeners according to the present invention;

[0041] Figure 2 This is a schematic diagram illustrating the formation of a three-dimensional model of a component according to Embodiment 1 of the present invention;

[0042] Figure 3 This is a schematic diagram illustrating the formation of a reference coordinate system according to Embodiment 1 of the present invention;

[0043] Figure 4 This is a schematic diagram illustrating the obtained slice geometry according to Embodiment 1 of the present invention;

[0044] Figure 5 This is a schematic diagram illustrating the initialization of the slice outline path according to Embodiment 1 of the present invention;

[0045] Figure 6 This is a schematic diagram illustrating the main shape path obtained according to Embodiment 1 of the present invention;

[0046] Figure 7 This is a schematic diagram illustrating the segmentation of the main shape path L3 of the housing according to Embodiment 1 of the present invention;

[0047] Figure 8 This is a schematic diagram illustrating the rearrangement of a set of path location points according to Embodiment 1 of the present invention;

[0048] Figure 9 is a schematic diagram for exemplarily showing the bias operation on the path of each longitudinal inner rib according to the first embodiment of the present application;

[0049] Figure 10 is a schematic diagram for exemplarily showing the stacking path planning of each longitudinal inner rib according to the first embodiment of the present application;

[0050] Figure 11 is a schematic diagram for exemplarily showing the finally obtained component stacking path according to the first embodiment of the present application;

[0051] Figure 12 is a schematic diagram for exemplarily showing the formation of a three-dimensional model of a component according to the second embodiment of the present application;

[0052] Figure 13 is a schematic diagram for exemplarily showing the formation of a reference coordinate system according to the second embodiment of the present application;

[0053] Figure 14 is a schematic diagram for exemplarily showing the obtained slice geometry according to the second embodiment of the present application;

[0054] Figure 15 is a schematic diagram for exemplarily showing the initialization of a slice contour path according to the second embodiment of the present application;

[0055] Figure 16 is a schematic diagram for exemplarily showing the obtained main shape path according to the second embodiment of the present application;

[0056] Figure 17 is a schematic diagram for exemplarily showing the segmentation of a housing main shape path L3 according to the second embodiment of the present application;

[0057] Figure 18 is a schematic diagram for exemplarily showing the rearrangement of a set of path position points according to the second embodiment of the present application;

[0058] Figure 19 is a schematic diagram for exemplarily showing the bias operation on the path of each longitudinal inner rib according to the second embodiment of the present application;

[0059] Figure 20 is a schematic diagram for exemplarily showing the stacking path planning of each longitudinal inner rib according to the second embodiment of the present application;

[0060] Figure 21 is a schematic diagram for exemplarily showing the finally obtained component stacking path according to the second embodiment of the present application. DETAILED DESCRIPTION

[0061] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0062] Figure 1 is a main process flow chart showing an electric arc additive manufacturing method of an aluminum alloy thin-walled shell with longitudinal ribbed plate according to the present application. As analyzed in the foregoing “background” section, the present application aims to solve the following problems existing in the prior art: ① interference easily occurs when the electric arc gun is inserted into the formed shell to accumulate the longitudinal ribbed plate, causing safety accidents; ② accumulation of the formed longitudinal ribbed plate on the inner surface of the shell easily leads to melting through of the thin wall of the shell due to excessive heat input, seriously reducing the manufacturing quality; ③ the accumulation paths of the inner and outer contours of the shell, the outer contour path of the longitudinal rib and the filling path are planned respectively and are not connected with each other, leading to an increase in the number of starting and extinguishing arcs in the electric arc additive manufacturing process, increasing local stress, causing deformation of the component, increasing defects and reducing the mechanical properties of the component.

[0063] The present application will be explained more specifically below with reference to the drawings. Figure 1

[0064] Step one is a modeling and reference coordinate system setting step.

[0065] In this step, a corresponding component three-dimensional model is established for the aluminum alloy thin-walled shell with longitudinal ribbed plate to be processed and manufactured, and a reference coordinate system containing XYZ three axes is set.

[0066] More specifically, first, the component three-dimensional model can be established according to the specified dimensions of the drawing, for example, taking the end face of one end in the height direction of the three-dimensional model as the reference face and the end face of the other end as the top face; the geometric center of the end face at the reference face is the origin O of the reference coordinate system, and the vertical distance direction between the reference face and the top face is the Z-axis direction of the reference coordinate system.

[0067] The X-axis direction can be set by the following method, for example: taking the plan view of the end face at the reference face, the origin O is the two-dimensional coordinate system origin on the plan view, and the Z-axis is perpendicular to the plan view and outward; a horizontal line passing through the origin O and directed to the right is denoted as the initial X-axis X0; the geometric shape on the plan view is rotated around the origin O, and X0 remains unchanged; since X0 remains unchanged, the x coordinates of each point on the geometric shape change with the rotation, until there is at most one X0 minimum point on the geometric shape, and the negative direction of X0 does not contact the contour of the longitudinal ribbed plate at this time, at which time X0 is the X-axis direction. ​

[0068] The Y-axis direction is established according to the right-hand rule with the origin O, the Z-axis, and the X-axis direction as references; after the reference coordinate system is set, the three-dimensional model is output.

[0069] Step two is the step of slicing the longitudinal inner rib plate together with the shell body.

[0070] In this step, all the longitudinal inner rib plates are sliced together with the shell body along the Z-axis direction, and a slice profile composed of an outer contour and an inner contour is obtained.

[0071] More specifically, the XOY plane defined in the above step can be defined as a tangent plane, and the tangent plane is used to perform planar cutting along the Z-axis direction to obtain a cross section of the three-dimensional model on the tangent plane, which is a slice; the geometry of the slice is composed of an outer contour and an inner contour, and the inner contour is divided into two parts: a shell part with a normal distance from the outer contour equal to the thickness of the shell body, and a longitudinal inner rib plate part with a normal distance from the outer contour greater than the thickness of the shell body.

[0072] In this process, the initial slice height is preferably set to 0.2-0.5 mm, and the slice height is preferably set to 70-90% of the height of a single pass of deposited metal starting from the second slice.

[0073] Step three is the initialization step of the slice profile path.

[0074] In this step, for the outer and inner contour paths corresponding to the outer and inner contours respectively, the position point sets contained therein are sorted according to the minimum value of the X-axis coordinate, and are arranged in the clockwise direction, thereby obtaining the initialized outer and inner contour paths.

[0075] More specifically, the path obtained after slicing is an inner and outer contour path, and the contour path is composed of a set of position points arranged in a certain order. The initialization of the starting position of the path is achieved by constraining the starting point of the point set to a certain feature point. The initialization of the direction of the path is achieved by constraining the sorting method of the point set.

[0076] For example, the specific method is as follows: first, the point set constituting the contour is sorted according to the X-axis coordinate, and the point with the minimum X-coordinate value is recorded as X1; then X1 is taken as the first point, and is stored in sequence according to the original point set to form a new point set L1; finally, based on the shoelace criterion, it is judged whether the direction of the geometric shape enclosed by the points in L1 is clockwise, if it is clockwise, the initialization is completed, and the point set L1 is recorded as L2; if it is not clockwise, the points in L1 are traversed in reverse, and are stored in a new point set L2 in sequence, to obtain a new point set L2 in the clockwise direction, and the initialization is completed. After the path initialization is completed, the new outer contour path is recorded as L2O, and the new inner contour path is recorded as L2I.

[0077] Step four is the step of extracting the main shape path.

[0078] In this step, for the shell, the initialized outer contour path is offset inward by a certain distance, and the new outer contour is extracted as the main shape path of the shell. For each longitudinal inner rib plate, the initialized inner contour path is offset outward by a corresponding distance, and the inner contour is extended to intersect with the new outer contour of the shell. The non-closed region between the intersection points is the main shape path of each longitudinal inner rib plate.

[0079] More specifically, for example, the main shape path of the shell can be extracted first, and then the main shape path of the longitudinal inner rib plate is extracted. For the shell, the outer contour L20 can be offset inward by a distance of 1 / 2 of the shell thickness, and the new outer contour L3 is extracted as the main shape path of the shell. For the longitudinal inner rib plate, the shape is mainly formed by the non-closed inner contour protruding inward on the shell and the partial enclosure of the shell. Therefore, the non-closed contour of the inner protrusion can be offset outward by a distance of 1 / 2 of the shell thickness, and then the contour is extended to intersect with L3. The new non-closed contour between the intersection points is the main shape path of the longitudinal inner rib plate, denoted as L4.

[0080] Step five is the rearrangement step of the main shape path.

[0081] In this step, the main shape path of the shell is divided into multiple parts by the intersection points, and the multiple parts are arranged in a clockwise direction. The main shape path of each longitudinal inner rib plate is closed in a clockwise direction, thereby completing the rearrangement of the main shape path.

[0082] More specifically, the intersection points of each longitudinal inner rib plate L4 and the shell L3 can divide L3 into multiple parts. Due to the distribution of the intersection points on L3, the two intersection points are sequentially recorded as ip1 and ip2 according to the clockwise direction of the point set on L3. Correspondingly, the L3 part between each longitudinal inner rib plate ip1 and ip2 and L4 forms a closed contour Lb. If the component has n longitudinal inner rib plates, n Lb can be obtained, denoted as Lb1 to Lbn. The L3 part between two adjacent Lb is denoted as Ls. Since the shape of the component slice is a closed ring structure, if the component has n longitudinal inner rib plates, n+1 Ls can be obtained, denoted as Ls1 to Lsn+1.

[0083] For each longitudinal inner rib plate Lb point set, take ip1 as the starting point and traverse in a clockwise direction to obtain a new point set Lbe. There are four large-angle inflection points in the Lbe point set, which are ip1, ip2, and two inner convex points, which are sequentially recorded as ip3 and ip4 in a clockwise direction. Finally, all Ls and Lbe point sets within the slice are combined in a clockwise direction to reorganize a new path point set L1st. For a component with n longitudinal inner rib plates, L1st = Ls1 + Lbe1 + Ls2 + Lbe2 + … + Lsn + Lben + Lsn+1.

[0084] Step six is the filling path planning step of the longitudinal inner rib plate.

[0085] In this step, the main shape path of each longitudinal inner rib plate is taken out in sequence along the clockwise direction, and the accumulation path is planned according to the main shape path, so as to obtain the accumulation path of each longitudinal inner rib plate.

[0086] More specifically, the main shape path Lbe of each longitudinal inner rib plate can be taken out in sequence along the clockwise direction, and the longitudinal inner rib plate path is planned based on Lbe to form the final path pn-final of each longitudinal inner rib plate, and the specific process is as follows: for the main shape path Lbe of each longitudinal inner rib plate, the path between ip1 and ip2 is recorded as p1, the path between ip2 and ip3 is recorded as p2, the path between ip3 and ip4 is recorded as p3, and the path between ip4 and ip1 is recorded as p4; p1-p4 are respectively offset by 50% of the single accumulation metal width distance to form pOL1-pOL4; the maximum vertical distance dc of the point on pOL3 to p1 is calculated, and the filling path is planned according to the value of dc. The specific planning process of the filling path is known in the art, which will be briefly introduced below.

[0087] 1) When dc≤70% of the single accumulation metal width:

[0088] First, p2 can be offset by (single accumulation metal width - overlap amount) to form pOL2s, and the intersection of pOL2s and p1 is calculated and recorded as is1. The path from ip1 to is1 along the clockwise direction of p1 is recorded as a new path pn1.

[0089] Second, p1 can be offset by (single accumulation metal width - overlap amount) to form pOL1s, and the intersection of pOL1s and p4 is calculated. If there is no intersection between pOL1s and p4, the intersection of pOL1s and p3 is calculated and recorded as is2. The new path from is2 to ip2 along the counterclockwise direction of p4, p3 and p2 is recorded as pn2.

[0090] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final. When accumulation is performed along the path, the arc is extinguished once at the end point is1 of pn1, and the arc is started once at the start point is2 of pn2. The process window adopted is recorded as process 1.

[0091] 2) When 70% of the single accumulation metal width < dc≤12mm:

[0092] It is judged whether pOL3 and pOL1 have an intersection between pOL2 and pOL4. Further, according to the intersection, the following multiple cases are handled:

[0093] If there is no intersection point:

[0094] First, offset p2 inward (single track accumulation metal width - overlap amount) distance, form pOL2s, calculate the intersection of pOL2s and p1, recorded as is1, the path from ip1 clockwise along the direction of p1 to is1 end recorded as new path pn1;

[0095] Second, offset p4 inward (single track accumulation metal width - overlap amount) distance, form pOL4s; for the closed area surrounded by pOL1~pOL4, calculate the center axis path with pOL2, pOL4 as the boundary, and then calculate the intersection of the center axis path and pOL2s, pOL4s, recorded as is2, is3 respectively; is2 is the starting point, is3 is the end point, and the path along the center axis direction is recorded as pn2;

[0096] Next, calculate the intersection of the extended line of the obtained center axis path and p4, recorded as is4, and the new path from is4 counterclockwise along p4, p3, p2 direction until ip2 end recorded as pn3;

[0097] Finally, combine the point sets of pn1, pn2, and pn3 to form the final path pn-final, and accumulate the continuous arc along the path, and the process window used by pn1 and pn2 is recorded as process 1; the process window used by pn3 is recorded as process 2;

[0098] If there is one intersection point close to pOL2, recorded as isx;

[0099] First, offset p2 inward (single track accumulation metal width - overlap amount) distance, form pOL2s, calculate the intersection of pOL2s and p1, recorded as is1, the path from ip1 clockwise along the direction of p1 to is1 end recorded as new path pn1;

[0100] Second, offset p4 inward (single track accumulation metal width - overlap amount) distance, form pOL4s; if pOL3 and pOL1 have an intersection point, and the intersection point is close to pOL2, then pOL1, pOL3, and pOL4s will form a closed area; calculate the center axis path of the closed area with the intersection point isx and pOL4s as the boundary, the starting point is isx, and the end point is located on pOL4s, and the path is recorded as pn2-1;

[0101] Next, calculate the intersection of the extended line of the obtained center axis path and p4, recorded as is2, and the new path from is2 counterclockwise along p4, p3, p2 direction until ip2 end recorded as pn2-2, arrange the point set of the path to the point set of pn2-1, and then combine to form a new path recorded as pn2;

[0102] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, along which the arc is extinguished once at the end point isx of pn1 and is ignited once at the start point is2 of pn2; the process window adopted by pn1 and pn2 is recorded as process 1; the process window adopted by pn1-2 is recorded as process 2.

[0103] ③ If there is one intersection point close to pOL4, the intersection point is recorded as isx;

[0104] First, p2 is inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection point of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 in the clockwise direction along p1 to the end point is1 is recorded as a new path pn1-1;

[0105] Second, if there is an intersection point between pOL3 and pOL1, and the intersection point is close to pOL4, then pOL1, pOL3 and pOL2s will enclose a closed area; the central axis path is calculated for the closed area with pOL2s and the intersection point isx as the boundaries, the start point is located on pOL2s, and the end point is isx, the path is recorded as pn1-2, and the path is arranged to the point set of pn1-1 to form a new path, which is recorded as pn1;

[0106] Next, p1 is inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL1s, the intersection point of pOL1s and p4 is calculated and recorded as is2, and the new path from is2 in the counterclockwise direction along p4, p3 and p2 to the end point ip2 is recorded as pn2;

[0107] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, along which the arc is extinguished once at the end point isx of pn1 and is ignited once at the start point is2 of pn2; the process window adopted by pn1 and pn2 is recorded as process 1; the process window adopted by pn1-2 is recorded as process 2.

[0108] ④ If there are two intersection points, the intersection point close to pOL2 is recorded as isx1, and the intersection point close to pOL4 is recorded as isx2;

[0109] First, p2 is inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection point of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 in the clockwise direction along p1 to the end point is1 is recorded as a new path pn1;

[0110] Secondly, offset the distance of pi to inward (single pass accumulated metal width - overlap amount) to form pOLIs, calculate the intersection of pOLIs and p4, record as is2, and the new path from is2 to ip2 along the direction of p4, p3, p2 in reverse clockwise direction is recorded as pn3;

[0111] Then, calculate the middle axis path of the closed area surrounded by isxl, pOL3, isx2, ipOLl, and the starting point is isxl and the ending point is isx2, and record the path as pn2;

[0112] Finally, combine the point sets of pn1, pn2 and pn3 to form the final path pn-final, and when accumulating along the path, extinguish the arc once at the ending point isl of pn1 and at the ending point isx2 of pn2, and start the arc once at the starting point isxl of pn2 and at the starting point is2 of pn3; the process window adopted by pn1 and pn3 is recorded as process 1, and the process window adopted by pn2 is recorded as process 3.

[0113] 3) If dc>12mm:

[0114] Firstly, offset the distance of pi to p4 to inward (single pass accumulated metal width - overlap amount) to form pOLIs and pOL4s, and offset the distance of pOL2s to inward (single pass accumulated metal width - overlap amount) to form pOL2t;

[0115] Secondly, calculate the intersection of pOL2s and pi, record as isl, and the path from ip1 to isl along the direction of pi in clockwise direction is recorded as new path pn1-1; then calculate the intersection of pOL3s and pOL2s, record as is2, and the path from isl to is2 along the direction of pOL2s is recorded as new path pn1-2, and the path is placed after pn1-1 to form new path point set pn1;

[0116] Then, calculate the intersection of pOLIs and p4, record as is3, and the new path from is3 to ip2 along the direction of p4, p3, p2 in reverse clockwise direction is recorded as pn3;

[0117] Then, calculate the intersection of pOL2t and pOL3s, record as is4, and the intersection of pOLIs and pOL4s, record as is5, and the area surrounded by pOLIs, pOL2t, pOL3s and pOL4s is recorded as A; draw a straight line parallel to the straight line connecting ip1 and ip2 through point is4, and rotate the straight line 45° counterclockwise with is4 as the center, and then offset the distance of interval (single pass accumulated metal width - overlap amount) to fill the area A to form the scanning path pn2, and the starting point of the path is is4 and the ending point is is5;

[0118] Finally, the point sets of pn1, pn2 and pn3 are combined in sequence to form the final path pn-final, along which the continuous arc is stacked, and the process window adopted is process 1

[0119] Step seven is the closed loop stacking path forming step and the electric arc additive manufacturing step.

[0120] In this step, the main shape path of the shell after the above steps is connected to the stacking path of all the longitudinal inner rib plates in a clockwise direction, and the final closed loop stacking path is obtained. Then, based on the final closed loop stacking path, the electric arc additive manufacturing process is used to form each stacking layer in a ring direction once, until the required aluminum alloy thin-walled shell with longitudinal inner rib plates is obtained.

[0121] More specifically, after the previous steps, the final paths pn-final1 to pn-finaln of the first to nth rib plates have been obtained. Then, the shell part paths Ls1~Lsn+1 in the original slice are taken out in sequence in a clockwise direction, and the new path point set L2nd is obtained by recombining the longitudinal inner rib plates. For a component with n longitudinal inner rib plates, L2nd=Ls1+pn-final1+Ls2+pn-final2+…+Lsn+pn-finaln+Lsn+1.

[0122] Then, the stacking path point set is converted into a set of spatial position coordinates recognizable by the robot, and 6-axis motion code, and is imported into the robot control terminal. Accordingly, the electric arc additive manufacturing process is used to complete the machining and manufacturing of the entire component.

[0123] The various processing steps of the present application will be explained more clearly in combination with two specific embodiments.

[0124] Embodiment one

[0125] This embodiment one relates to a thin-walled shell component with an outer diameter of 318 mm, a height of 1.6 m, a wall thickness of 3 mm, and 8 symmetrically distributed longitudinal inner rib plates in the inner wall. The following will be specifically explained in combination with Figures 2 to 11 .

[0126] As shown in Figure 2 , the component is composed of a shell and longitudinal inner rib plates 1-8, wherein longitudinal inner rib plate 1 and longitudinal inner rib plate 2, longitudinal inner rib plate 3 and longitudinal inner rib plate 4 are located at the quadrant points of the shell cross section and are symmetric about the geometric center of the cross section, longitudinal inner rib plate 5 and longitudinal inner rib plate 6 are symmetric about longitudinal inner rib plate 3, and longitudinal inner rib plate 7 and longitudinal inner rib plate 8 are symmetric about longitudinal inner rib plate 4.

[0127] As shown in Figure 3As shown, for example, the lower end face A of the component can be used as the reference plane, and its corresponding upper end face B in the height direction can be used as the top surface; the geometric center of end face A is the origin O, and the height direction of the component is the Z-axis. The X-axis direction is set as follows: Take a top view of the end face at the reference plane, the origin O is on the top view, and is the origin of the two-dimensional coordinate system, the Z-axis is perpendicular to the top view and points outward; the horizontal line passing through the origin O and pointing to the right is the initial X-axis, denoted as X0; rotate the geometry on the top view around the origin O, keeping X0 stationary; since X0 is stationary, the X coordinate values ​​of each point on the geometry change continuously with the rotation until there is at most one minimum X value point on the geometry, and at the same time, the negative direction of X0 does not contact the contour of any longitudinal inner stiffener. At this time, X0 is the set X-axis. The Y-axis direction is established with reference to the origin O, the Z-axis, and the X-axis direction, according to the right-hand rule; finally, a top view of the relative position of the reference coordinate system and the component is established.

[0128] like Figure 4 As shown, for example, the XOY plane can be used to cut along the Z-axis to obtain a planar slice. The initial slice height is 0.2mm. Starting from the second layer of slices, the slice height is set to 70% of the single-pass metal stacking height. In this embodiment, the single-pass metal stacking height is 2.3mm, so the slice height starting from the second layer of slices is 1.6mm.

[0129] slice geometry such as Figure 4 It consists of an outer contour and an inner contour of the component. The inner contour is divided into two parts: the part that is at a normal distance from the outer contour equal to the shell thickness belongs to the shell and is denoted as SP. Figure 4 As shown by the dashed lines on the inner contour, the portion whose distance from the outer contour normal is greater than the shell thickness belongs to the longitudinal inner stiffeners, corresponding to longitudinal inner stiffeners 1 to 8 and respectively denoted as BP1 to 8, as follows. Figure 4 As shown by the solid lines on the inner contour.

[0130] like Figure 5 As shown in the figure, the X-axis coordinate values ​​of each point in the inner and outer contour path point sets obtained after slicing are traversed, and the point with the smallest X-coordinate value on the inner and outer contours is recorded, which are P respectively. ILxmin P OLxmin; then, the minimum point can be stored in a new point set container as the first point, and the points after the minimum point in the original point set are stored in the new point set container in sequence, and finally the points before the minimum point in the original point set are stored in the new point set container in sequence, forming a new point set L1; then, for example, based on the shoelace criterion, it can be judged whether the direction of the geometric shape formed by the points in L1 arranged in the storage order is clockwise, if it is clockwise, the initialization is completed, and the point set L1 is recorded as L2; if it is not clockwise, the points in L1 are traversed in reverse, and are stored in a new point set L2 in sequence, to obtain a new point set L2 in a clockwise direction, and the initialization is completed; the direction of the path in the slice after initialization is as shown in Figure 5 , after initialization, the outer contour path is L 2O , and the inner contour path is L 2I .

[0131] As shown in Figure 6 , first, the initialized outer contour L 2O is offset inward by a distance of 1 / 2 of the shell thickness to form a path L3, which is the main shape path of the shell; for the application example, the shell thickness is 3mm, so L 2O is offset inward by 1.5mm to obtain L3; then, the initialized inner contour L 2I is offset outward by a distance of 1 / 2 of the shell thickness, i.e. 1.5mm, corresponding to the BP1-BP8 contour parts of the longitudinal inner rib plates 1-8, to obtain the offset contour of each longitudinal inner rib plate, which is uniformly recorded as L4-0; finally, L4-0 of each longitudinal inner rib plate is extended to intersect with L3, i.e. the main shape path of each longitudinal inner rib plate is extracted, which is recorded as L4-1-L4-8 corresponding to the longitudinal inner rib plates 1-8 respectively; Figure 6 are the main shape paths extracted in the application example, the dashed line is the main shape path L3 of the shell, and the solid lines are the main shape paths L4-1-L4-8 of the longitudinal inner rib plates, P start is the point obtained after the P OLxmin is offset inward in Figure 5 .

[0132] As shown in Figure 7 , the main shape path of each longitudinal inner rib plate and the main shape path L3 of the shell both have two intersection points, which are uniformly recorded as ip1 and ip2 in sequence in the clockwise direction. The ip1 and ip2 of each longitudinal inner rib plate are defined as a group of intersection points, and in this embodiment one, there are 8 longitudinal inner rib plates, so there are 8 groups, a total of 16 intersection points; the intersection points are distributed on L3, which divides L3 into multiple parts; Figure 7In this example, the L3 portion between each group of ip1 and ip2 corresponds to 8 longitudinal inner stiffeners, denoted as Lb1 to Lb8 respectively; the L3 portion between adjacent groups is uniformly marked as Ls, and is sorted clockwise starting from Pstart; since the component slice shape is a closed ring structure, if there are n longitudinal inner stiffeners, then n+1 Ls can be obtained. For this embodiment, n=8, then there are 9 Ls, which are sorted clockwise starting from Pstart as Ls1 to Ls9.

[0133] like Figure 8 As shown, Lb1 and L4-1, Lb2 and L4-2, Lb3 and L4-3, Lb4 and L4-4, Lb5 and L4-5, Lb6 and L4-6, Lb7 and L4-7, and Lb8 and L4-8 can be paired to form closed paths for the longitudinal inner stiffeners 1 to 8. To obtain the independent clockwise closed path for each longitudinal inner stiffener, L4-1 to L4-8 are first extracted and then traversed in reverse order, stored as a new path point set, denoted as Le4-1 to L4-8. e4-8; then place Le4-1 to Le4-8 after paths Lb1 to Lb8 respectively, forming independent clockwise closed paths for longitudinal inner stiffeners 1 to 8, denoted as Lbe1 to Lbe8 respectively to correspond to the 8 longitudinal inner stiffeners; each closed path starts and ends at ip1 and has 4 inflection points including ip1 and ip2. In addition to ip1 and ip2, the other two inflection points are denoted as ip3 and ip4 in the clockwise direction of the path.

[0134] Then press Figure 8 The paths Ls1, Lbe5, Ls2, Lbe1, Ls3, Lbe7, Ls4, Lbe4, Ls5, Lbe8, Ls6, Lbe2, Ls7, Lbe6, Ls8, Lbe3, and Ls9 are sequentially stored in the container. After rearrangement, the final result is P. start A new path point set L with starting and ending points 1st It can be seen that L 1st =Ls1+Lbe5+Ls2+Lbe1+Ls3+Lbe7+Ls4+Lbe4+Ls5+Lbe8+Ls6+Lbe2+Ls7+Lbe6+Ls8+Lbe3+Ls9.

[0135] like Figure 9 As shown, the required single-pass stacked metal width and overlap amount are designed first; the single-pass stacked metal width = shell thickness + 2 * single-sided machining allowance, the single-sided machining allowance is 1.5~3mm, and the overlap amount is 25~42% of the single-pass stacked metal width; for this application example, the shell thickness is 3mm, the single-sided machining allowance is 1.5mm, then the single-pass stacked metal width is 6mm; the overlap amount is 30% of the single-pass stacked metal width, which is 1.8mm.

[0136] Secondly, the closed path point sets Lbe1-Lbe8 of the longitudinal inner rib plates 1-8 in L1st are extracted, and path biasing operations are performed respectively. Figure 9 In the middle, the path part between the two points ip1 and ip2 of each closed path is denoted as p1, the path part between the two points ip2 and ip3 is denoted as p2, the path part between the two points ip3 and ip4 is denoted as p3, and the path between the two points ip4 and ip1 is denoted as p4; p1-p4 are respectively biased inward by 50% of the width of the single-channel deposited metal, i.e., by 3 mm, to form pOL1-pOL4, as shown by the dashed lines in the middle of FIG. 4. Figure 9 In the middle, the path part between the two points ip1 and ip2 of each closed path is denoted as p1, the path part between the two points ip2 and ip3 is denoted as p2, the path part between the two points ip3 and ip4 is denoted as p3, and the path between the two points ip4 and ip1 is denoted as p4; p1-p4 are respectively biased inward by 50% of the width of the single-channel deposited metal, i.e., by 3 mm, to form pOL1-pOL4, as shown by the dashed lines in the middle of FIG. 4.

[0137] As shown in the middle of FIG. 4, the path planning is performed on Lbe1-Lbe8 according to the biasing operation results. The specific process is as follows: Figure 10

[0138] ① For Lbe1 and Lbe2:

[0139] Since dc of Lbe1 and Lbe2 is greater than 70% of the width of the single-channel deposited metal and less than 12 mm, and there is no intersection point between pOL3 and pOL1, first, p2 is biased inward by (the width of the single-channel deposited metal - the overlap amount), to form pOL2s, the intersection point of pOL2s and p1 is calculated and denoted as is1, and the path from ip1 to is1 along the direction of p1 is denoted as a new path pn1.

[0140] Secondly, p4 is biased inward by (the width of the single-channel deposited metal - the overlap amount), to form pOL4s; the central axis path is calculated with pOL2 and pOL4 as the boundaries, and the intersection points of the central axis path and pOL2s and pOL4s are respectively denoted as is2 and is3; is2 is the starting point, is3 is the ending point, and the path along the direction of the central axis is denoted as pn2.

[0141] Next, the intersection point of the extension line of the obtained central axis path and p4 is calculated and denoted as is4, and the new path from is4 to ip2 along the directions of p4, p3, and p2 in turn is denoted as pn3.

[0142] Finally, the point set of pn1, pn2, and pn3 is combined to form the final path pn-final, and the path is continuously curved when deposition is performed along the path; the process window adopted by pn1 and pn2 is denoted as process 1; and the process window adopted by pn3 is denoted as process 2.

[0143] ② For Lbe3 and Lbe4:

[0144] ​Since dc of Lbe3 and Lbe4 is greater than 12mm, first, p1-p4 are sequentially offset inward (single track accumulation metal width - overlap amount) by a distance to form pOL1s-pOL4s, pOL2s is offset inward (single track accumulation metal width - overlap amount) by a distance to form pOL2t;

[0145] Secondly, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 clockwise along p1 direction to the end of is1 is recorded as a new path pn1-1; and the intersection of pOL3s and pOL2s is calculated and recorded as is2, and the path from is1 along pOL2s direction to the end of is2 is recorded as a new path pn1-2, which is placed after pn1-1 to form a new path point set pn1;

[0146] Then, the intersection of pOL1s and p4 is calculated and recorded as is3, and the new path from is3 counterclockwise along p4, p3, p2 direction to the end of ip2 is recorded as pn3;

[0147] Then, the intersection of pOL2t and pOL3s is calculated and recorded as is4, the intersection of pOL1s and pOL4s is recorded as is5, and the area surrounded by pOL1s, pOL2t, pOL3s and pOL4s is recorded as A; a straight line parallel to the straight line connecting ip1 and ip2 is drawn through point is4, and after rotating the straight line 45° counterclockwise with is4 as the center, the area A is offset and filled by an interval (single track accumulation metal width - overlap amount) distance to form a scanning path pn2, which starts from is4 and ends at is5;

[0148] Finally, the point sets of pn1, pn2 and pn3 are sequentially combined to form the final path pn-final, and when accumulation is carried out along the path, the continuous arc is adopted, and the process window is process 1;

[0149] ③For Lbe5:

[0150] Since dc of Lbe5 is less than 70% of single track accumulation metal width, first, p2 is offset inward (single track accumulation metal width - overlap amount) by a distance to form pOL2s, and the intersection of pOL2s and p1 is calculated and recorded as is1, and the new path from ip1 clockwise along p1 direction to the end of is1 is recorded as pn1;

[0151] Secondly, p1 is offset inward (single track accumulation metal width - overlap amount) by a distance to form pOL1s, and the intersection of pOL1s and p4 is calculated and recorded as is2, and the new path from is2 counterclockwise along p4, p3, p2 direction to the end of ip2 is recorded as pn2;

[0152] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, along which the arc is extinguished once at the end point is1 of pn1 and ignited once at the start point is2 of pn2, and the process window adopted is recorded as process 1.

[0153] (4) For Lbe6:

[0154] Since the dc of Lbe5 is less than 70% of the single-pass deposited metal width, p2 is first offset inward by a distance of (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 clockwise along p1 to is1 is recorded as a new path pn1;

[0155] Secondly, p1 is offset inward by a distance of (single-pass deposited metal width - overlap amount) to form pOL1s, and since pOL1s and p4 do not have an intersection, the intersection of pOL1s and p3 is calculated and recorded as is2, and the new path from is2 counterclockwise along p4, p3, and p2 to ip2 is recorded as pn2;

[0156] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, along which the arc is extinguished once at the end point is1 of pn1 and ignited once at the start point is2 of pn2, and the process window adopted is recorded as process 1.

[0157] (5) For Lbe7:

[0158] Since the dc of Lbe7 is greater than 70% of the single-pass deposited metal width and less than 12 mm, and pOL3 and pOL1 do not have an intersection, p2 is first offset inward by a distance of (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 clockwise along p1 to is1 is recorded as a new path pn1;

[0159] Secondly, p4 is offset inward by a distance of (single-pass deposited metal width - overlap amount) to form pOL4s; the enclosed area formed by pOL1-pOL4 is bounded by pOL2 and pOL4 to calculate the central axis path, and the intersection of the central axis path and pOL2s and pOL4s is calculated and recorded as is2 and is3, respectively; is2 is the starting point and is3 is the ending point, and the path along the central axis direction is recorded as pn2;

[0160] Next, the intersection of the extension line of the obtained central axis path and p4 is calculated and recorded as is4, and the new path from is4 counterclockwise along p4, p3, and p2 to ip2 is recorded as pn3;

[0161] Finally, the point set of pn1, pn2, pn3 is combined to form the final path pn-final, along which the continuous arc is stacked, the process window adopted by pn1 and pn2 is recorded as process 1; the process window adopted by pn3 is recorded as process 2.

[0162] ⑥For Lbe8:

[0163] Since the dc of Lbe8 is greater than 70% of the single-channel stacked metal width and less than 12mm, and there is no intersection point between pOL3 and pOL1, first, p2 is offset inward (single-channel stacked metal width - overlap amount) by a distance to form pOL2s, the intersection point of pOL2s and p1 is recorded as is1, and the path from ip1 clockwise along p1 direction to is1 is recorded as the new path pn1.

[0164] Secondly, p4 is offset inward (single-channel stacked metal width - overlap amount) by a distance to form pOL4s; the closed area surrounded by pOL1~pOL4 is calculated as the central axis path with pOL2, pOL4 as the boundary, and then the intersection points of the central axis path and pOL2s, pOL4s are calculated, respectively recorded as is2, is3; is2 is the starting point, is3 is the ending point, and the path along the central axis direction is recorded as pn2.

[0165] Next, the intersection point of the extension line of the obtained central axis path and p4 is calculated, recorded as is4, and the new path from is4 counterclockwise along p4, p3, p2 direction to ip2 is recorded as pn3.

[0166] Finally, the point set of pn1, pn2, pn3 is combined to form the final path pn-final, along which the continuous arc is stacked, the process window adopted by pn1 and pn2 is recorded as process 1; the process window adopted by pn3 is recorded as process 2.

[0167] As shown in Figure 11 After the previous steps, the stacking path pn-final of each longitudinal inner rib plate has been obtained, corresponding to the first to eighth longitudinal inner rib plates, recorded as pn-final1~pn-final8 in turn; again, an empty two-dimensional path point set container L 2nd is created, and the shell part paths Ls1~Ls9 in the first rearranged path L 1st are taken out in clockwise direction in turn, and stored to L 2ndIn this embodiment, the storage order is as follows: Ls1, pn-final5, Ls2, pn-final1, Ls3, pn-final7, Ls4, pn-final4, Ls5, pn-final8, Ls6, pn-final2, Ls7, pn-final6, Ls8, pn-final3, Ls9; and the rearranged L 2nd The path point set is the final stacking path planned by the component.

[0168] The stacking path planned is compiled and converted into a set of spatial position coordinates recognizable by the robot and 6-axis motion codes, which are imported into the robot control terminal; accordingly, the component is manufactured by using the electric arc additive process. In this embodiment, the wire material used in the electric arc additive manufacturing is 5A06 aluminum alloy, the substrate is pure aluminum plate, and the protective gas type and flow rate are 99.999% high-purity Ar and 23 L / min.

[0169] The detailed parameters corresponding to processes 1-2 in the foregoing step are as follows:

[0170] Process 1: stacking current 172 A, stacking voltage 23.1 V, stacking speed 0.9 mm / min;

[0171] Process 2: stacking current 124 A, stacking voltage 22.1 V, stacking speed 0.85 mm / min;

[0172] The mechanical properties, forming size deviation, and internal defect conditions of the final component are shown in Table 1:

[0173]

[0174] Table 1

[0175] Example Two

[0176] This example two relates to a thin-walled shell component with a length of 620 mm, a width of 400 mm, a height of 1.2 m, a wall thickness of 5 mm, and 10 longitudinal inner rib plates in the inner wall. The following will be specifically described in combination with Figures 12 to 21 .

[0177] As shown in Figure 12 , the component is composed of a shell and longitudinal inner rib plates 1-10, wherein the longitudinal inner rib plate 1 and the longitudinal inner rib plate 2, the longitudinal inner rib plate 3 and the longitudinal inner rib plate 4, and the longitudinal inner rib plate 5 and the longitudinal inner rib plate 6 are distributed on the short side of the shell, and the longitudinal inner rib plates 7-10 are distributed on the long side of the longitudinal inner rib plate.

[0178] As shown in Figure 13 , for example, the Figure 12The lower end surface A of the middle component is taken as a reference surface, and the corresponding upper end surface B in the height direction is a top surface; the geometric center of the end surface A is taken as the origin O, and the component height direction is taken as the Z axis. The X axis direction is set as follows: taking the plan view of the end surface at the reference surface, the origin O is taken as the origin of the two-dimensional coordinate system on the plan view, and the Z axis is taken as being perpendicular to the plan view and extending outward; a horizontal line passing through the origin O and extending to the right is taken as the initial X axis, denoted as X0; the geometric shape on the plan view is rotated around the origin O, and the X0 remains unchanged; since the X0 remains unchanged, the X coordinate values of all points on the geometric shape continuously change with the rotation, until there is at most one X minimum value point on the geometric shape, and the negative direction of the X0 does not contact the profile of any longitudinal inner rib plate, at which time the X0 is taken as the set X axis. The Y axis direction is established according to the right-hand rule with reference to the origin O, the Z axis and the X axis direction; finally, the plan view of the relative position of the reference coordinate system and the component is established.

[0179] As shown in Figure 14 , the XOY plane can be used to perform planar cutting along the Z axis direction to obtain a planar slice, and the initial slice height is 0.4 mm; from the second slice, the slice height is set to be 80% of the single-track accumulated metal height; in the application example, the single-track accumulated metal height is 2.6 mm, so the slice height from the second slice is 2.08 mm. The slice geometric shape is as shown in Figure 14 , which is composed of the outer profile and the inner profile, wherein the inner profile is divided into two parts: the part with a normal distance from the outer profile equal to the shell thickness belongs to the shell and is denoted as SP, as shown in Figure 14 ; the part with a normal distance from the outer profile greater than the shell thickness belongs to the longitudinal inner rib plate and is denoted as BP1-BP10 corresponding to the longitudinal inner rib plates 1-10, as shown in Figure 14 .

[0180] As shown in Figure 15 , the X axis coordinate values of all points in the inner and outer profile path point sets obtained after slicing are traversed respectively, and the points with the minimum X coordinate values on the inner and outer profiles are recorded, respectively denoted as P ILxmin and P OLxmin ; then a new point set container is created, the minimum value points are stored in the new point set container as the first points, and the points after the minimum value points in the original point set are sequentially stored in the new point set container, and finally the points before the minimum value points in the original point set are sequentially stored in the new point set container, forming a new point set L1. For example, whether the direction of the geometric shape surrounded by all points in L1 arranged in the storage order is clockwise or counterclockwise can be judged based on the shoelace criterion; if it is clockwise, the initialization is completed, and the point set L1 is denoted as L2; if it is not clockwise, the points in L1 are traversed in reverse and sequentially stored in a new point set L2, to obtain a new point set L2 in the clockwise direction, and the initialization is completed; the direction of the slice inner path after initialization is as shown in Figure 15After initialization, the outer contour path is L. 2O The inner contour path is L 2I .

[0181] like Figure 16 As shown in the figure, firstly, the initialized outer contour L 2O Offset inward by 1 / 2 the shell thickness to form path L3, which is the main shape path of the shell; in this application example, the shell thickness is 5mm, then L... 2O Offset inward by 2.5mm to obtain L3; then, initialize the inner contour L... 2I The outline of each longitudinal inner stiffener 1 to 10 is offset outward by 1 / 2 shell thickness, i.e., 2.5mm, to obtain the offset outline of each longitudinal inner stiffener, which is uniformly denoted as L4-0; finally, the L4-0 of each longitudinal inner stiffener is extended to intersect with L3, that is, the main shape path of each longitudinal inner stiffener is extracted, which is denoted as L4-1 to L4-10 respectively corresponding to longitudinal inner stiffener 1 to 10. Figure 16 The main shape paths extracted in this application example are shown below. The dashed line represents the main shape path L3 of the shell, and the solid lines represent the main shape paths L4-1 to L4-10 of the longitudinal internal stiffeners. start for Figure 15 China P OLxmin The point obtained after inward bias is also the start and end point of L3.

[0182] like Figure 17 As shown, each longitudinal inner stiffener has two intersection points with the main shape path of the shell's main shape path L3. These two intersection points are denoted as ip1 and ip2 in a clockwise direction. Each longitudinal inner stiffener's ip1 and ip2 are defined as a set of intersection points. In this application example, there are 10 longitudinal inner stiffeners, so there are 10 sets, totaling 20 intersection points. These intersection points are distributed on L3, dividing L3 into multiple parts. Figure 17 In this context, the L3 portion between each group of ip1 and ip2 corresponds to 10 longitudinal internal stiffening plates, denoted as Lb1 to Lb10 respectively; the L3 portion between adjacent groups is uniformly marked as Ls, and is determined by P. start Start by sorting in a clockwise direction; since the component slices are in a closed ring shape, if there are n longitudinal inner stiffeners, then n+1 Ls can be obtained. In this embodiment, n=10, so there are 11 Ls, which are sorted in a clockwise direction from Pstart as Ls1 to Ls11.

[0183] like Figure 18As shown, Lb1 and L4-1, Lb2 and L4-2, Lb3 and L4-3, Lb4 and L4-4, Lb5 and L4-5, Lb6 and L4-6, Lb7 and L4-7, Lb8 and L4-8, Lb9 and L4-9, and Lb10 and L4-10 can be paired to form closed paths for longitudinal inner stiffeners 1 to 10. To obtain an independent clockwise closed path for each longitudinal inner stiffener, L4-1 to L4-10 are first extracted and then traversed in reverse order, stored as a new path point set, denoted as... Let Le4-1 to Le4-10 be the 10 longitudinal internal stiffeners. Then, place Le4-1 to Le4-10 after the paths Lb1 to Lb10 to form independent clockwise closed paths for the longitudinal internal stiffeners 1 to 10, which are denoted as Lbe1 to Lbe10 to correspond to the 10 longitudinal internal stiffeners. Each closed path starts and ends at ip1 and has 4 inflection points including ip1 and ip2. In addition to ip1 and ip2, the other two inflection points are denoted as ip3 and ip4 in the clockwise direction of the path.

[0184] Create an empty 2D path point set container, then press Figure 18 The paths Ls1, Lbe7, Ls2, Lbe3, Ls3, Lbe1, Ls4, Lbe4, Ls5, Lbe9, Ls6, Lbe10, Ls7, Lbe6, Ls8, Lbe2, Ls9, Lbe5, Ls10, Lbe8, and Ls11 are sequentially stored in the container. After rearrangement, the final result is P. start A new path point set L with starting and ending points 1st It can be seen that L 1st =Ls1+Lbe7+Ls2+Lbe3+Ls3+Lbe1+Ls4+Lbe4+Ls5+Lbe9+Ls6+Lbe10+Ls7+Lbe6+Ls8+Lbe2+Ls9+Lbe5+Ls10+Lbe8+Ls11.

[0185] like Figure 19 As shown, firstly, the required single-pass metal stacking width and overlap amount are designed; single-pass metal stacking width = shell thickness + 2 * single-sided machining allowance, the single-sided machining allowance is 1.5~3mm, and the overlap amount is 25~42% of the single-pass metal stacking width; for this embodiment, the shell thickness is 5mm, the single-sided machining allowance is 2mm, then the single-pass metal stacking width is 9mm; the overlap amount is 40% of the single-pass metal stacking width, which is 3.6mm; secondly, L is extracted. 1st For the closed path point sets Lbe1 to Lbe10 of the longitudinal inner stiffeners 1 to 10, respectively, path offset operations are performed. Figure 19In the middle, the path part between ip1 and ip2 of each closed path is recorded as p1, the path part between ip2 and ip3 is recorded as p2, the path part between ip3 and ip4 is recorded as p3, and the path part between ip4 and ip1 is recorded as p4; p1-p4 are respectively offset by 50% of the width of the single-channel accumulated metal, i.e. offset by 3mm, to form pOL1-pOL4, as shown by the dashed lines in the middle. Figure 19 In the middle, the path part between ip1 and ip2 of each closed path is recorded as p1, the path part between ip2 and ip3 is recorded as p2, the path part between ip3 and ip4 is recorded as p3, and the path part between ip4 and ip1 is recorded as p4; p1-p4 are respectively offset by 50% of the width of the single-channel accumulated metal, i.e. offset by 3mm, to form pOL1-pOL4, as shown by the dashed lines in the middle.

[0186] As shown in the middle, the path planning is performed on Lbe1-Lbe10 according to the offset operation results, and the specific operation is as follows: Figure 20

[0187] ① For Lbe1 and Lbe2:

[0188] Since the dc of Lbe1 and Lbe2 is greater than 12mm, p1-p4 are first offset by the width of the single-channel accumulated metal minus the overlap amount, to form pOL1s-pOL4s, and pOL2s is offset by the width of the single-channel accumulated metal minus the overlap amount, to form pOL2t.

[0189] Secondly, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 to is1 along p1 is recorded as a new path pn1-1; then the intersection of pOL3s and pOL2s is calculated and recorded as is2, and the path from is1 to is2 along pOL2s is recorded as a new path pn1-2, which is placed after pn1-1 to form a new path point set pn1.

[0190] Next, the intersection of pOL1s and p4 is calculated and recorded as is3, and the new path from is3 to ip2 along p4, p3 and p2 in reverse is recorded as pn3.

[0191] Next, the intersection of pOL2t and pOL3s is calculated and recorded as is4, the intersection of pOL1s and pOL4s is recorded as is5, and the area surrounded by pOL1s, pOL2t, pOL3s and pOL4s is recorded as A; a straight line parallel to the straight line connecting ip1 and ip2 is drawn through is4, and the straight line is rotated counterclockwise by 45° with is4 as the center, and then the area A is offset by the width of the single-channel accumulated metal minus the overlap amount to form a scanning path pn2, which starts at is4 and ends at is5.

[0192] Finally, the point sets of pn1, pn2 and pn3 are combined to form the final path pn-final, and the process window adopted when accumulating along the path is process 1.

[0193] ​② For Lbe3 and Lbe4:

[0194] Since dc of Lbe3 and Lbe4 is less than 70% of the single-pass deposited metal width, first, p2 is inwardly offset by a distance of (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 clockwise along p1 to the end of is1 is recorded as a new path pn1;

[0195] Secondly, p1 is inwardly offset by a distance of (single-pass deposited metal width - overlap amount) to form pOL1s, the intersection of pOL1s and p4 is calculated and recorded as is2, and the new path from is2 counterclockwise along p4, p3, p2 to the end of ip2 is recorded as pn2;

[0196] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, and when depositing along the path, the arc is extinguished once at the end point is1 of pn1 and the arc is ignited once at the start point is2 of pn2, and the process window used is recorded as process 1.

[0197] ③ For Lbe5:

[0198] Since dc of Lbe5 is greater than 70% of the single-pass deposited metal width and less than 12 mm, and the intersection isx of pOL3 and pOL1 is close to pOL4, first, p2 is inwardly offset by a distance of (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path from ip1 clockwise along p1 to the end of is1 is recorded as a new path pn1-1;

[0199] Secondly, if there is an intersection between pOL3 and pOL1, and the intersection is close to pOL4, then pOL1, pOL3, and pOL2s will form a closed area; for the closed area, the central axis path is calculated with pOL2s and the intersection isx as the boundary, the starting point is located on pOL2s, and the end point is isx, and the path is recorded as pn1-2, and the path is arranged to the point set of pn1-1 to form a new path, which is recorded as pn1;

[0200] Then, p1 is inwardly offset by a distance of (single-pass deposited metal width - overlap amount) to form pOL1s, the intersection of pOL1s and p4 is calculated and recorded as is2, and the new path from is2 counterclockwise along p4, p3, p2 to the end of ip2 is recorded as pn2;

[0201] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, along which the arc is extinguished once at the end point is1 of pn1 and is ignited once at the start point isx of pn2; the process window adopted by pn1 and pn2-2 is recorded as process 1; the process window adopted by pn2-1 is recorded as process 2.

[0202] (4) For Lbe6:

[0203] Since the dc of Lbe6 is greater than 70% of the single-pass deposited metal width and less than 12 mm, and the intersection isx of pOL3 and pOL1 is close to pOL2, first, p2 is inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL2s, the intersection of pOL2s and p1 is calculated and recorded as is1, and the path clockwise along p1 direction from ip1 to is1 is recorded as a new path pn1;

[0204] Secondly, p4 is inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL4s; if there is an intersection between pOL3 and pOL1, and the intersection is close to pOL2, then pOL1, pOL3 and pOL4s will enclose a closed area; the central axis path is calculated with the intersection isx and pOL4s as the boundary, the starting point is isx, and the end point is located on pOL4s, and the path is recorded as pn2-1;

[0205] Then, the intersection of the extension line of the obtained central axis path and p4 is calculated and recorded as is2, and the new path clockwise along p4, p3 and p2 directions from is2 to ip2 is recorded as pn2-2; after arranging the point set of the path to the point set of pn2-1, the new path is combined and recorded as pn2;

[0206] Finally, the point set of pn1 and pn2 is combined to form the final path pn-final, along which the arc is extinguished once at the end point is1 of pn1 and is ignited once at the start point isx of pn2; the process window adopted by pn1 and pn2-2 is recorded as process 1; the process window adopted by pn2-1 is recorded as process 2.

[0207] (5) For Lbe7 and Lbe8:

[0208] Since the dc of Lbe7 and Lbe8 is greater than 12 mm, first, p1-p4 are sequentially inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL1s-pOL4s, and pOL2s is inwardly offset by a distance (single-pass deposited metal width - overlap amount) to form pOL2t;

[0209] Secondly, the intersection of pOL2s and pi is calculated and recorded as is1. The path from ip1 to is1 along the direction of pi is recorded as a new path pn1-1. Then the intersection of pOL3s and pOL2s is calculated and recorded as is2. The path from is1 to is2 along the direction of pOL2s is recorded as a new path pn1-2. The new path pn1-2 is placed after pn1-1 to form a new path point set pn1.

[0210] Then, the intersection of pOL1s and p4 is calculated and recorded as is3. The new path from is3 to ip2 along the direction of p4, p3 and p2 is recorded as pn3.

[0211] Then, the intersection of pOL2t and pOL3s is calculated and recorded as is4, and the intersection of pOL1s and pOL4s is calculated and recorded as is5. The area surrounded by pOL1s, pOL2t, pOL3s and pOL4s is recorded as A. A straight line parallel to the straight line connecting ip1 and ip2 is drawn through is4. The straight line is rotated 45° counterclockwise with is4 as the center, and the area A is filled by offsetting the distance of interval (the width of single track of deposited metal - the amount of overlap) to form a scanning path pn2. The path pn2 has is4 as the starting point and is5 as the ending point.

[0212] Finally, the path point sets of pn1, pn2 and pn3 are combined to form a final path pn-final. The deposited metal is deposited along the path pn-final, and the process window is process 1.

[0213] As shown in FIG. 10, the deposited metal is deposited along the path pn-final, and the process window is process 1. Figure 21 After the above steps, the deposition paths pn-final of the longitudinal inner rib plates are obtained. The paths corresponding to the first to tenth longitudinal inner rib plates are recorded as pn-final1 to pn-final10, respectively. An empty two-dimensional path point set container L 2nd is newly created, and the shell part paths Ls1 to Ls11 in the rearranged path L 1st are sequentially taken out in the clockwise direction and stored in L 2nd together with pn-final1 to pn-final10. The storage order is as follows: Ls1, pn-final7, Ls2, pn-final3, Ls3, pn-final1, Ls4, pn-final4, Ls5, pn-final9, Ls6, pn-final10, Ls7, pn-final6, Ls8, pn-final2, Ls9, pn-final5, Ls10, pn-final8, Ls11. The rearranged L 2nd is the final deposition path of the component.

[0214] The accumulated path obtained by planning is compiled and converted into a set of spatial position coordinate data and 6-axis motion code recognizable by the robot, and is imported into the robot control terminal; accordingly, the machining and manufacturing are performed by using the electric arc additive manufacturing process. The wire material used in the electric arc additive manufacturing is 2319 aluminum alloy, the base plate is 2A12 aluminum alloy, the protective gas type and flow rate are 99.999% high-purity Ar, and the flow rate is 25 L / min.

[0215] The detailed parameters corresponding to processes 1-2 in the previous step are as follows:

[0216] Process 1: accumulation current 180 A, accumulation voltage 23.6 V, accumulation speed 0.85 mm / min;

[0217] Process 2: accumulation current 132 A, accumulation voltage 22.4 V, accumulation speed 0.64 mm / min;

[0218] The mechanical properties, forming size deviation and internal defect conditions of the finally obtained component are shown in Table 2:

[0219]

[0220] Table 2

[0221] In summary, by the present application, the plurality of longitudinal inner rib plates in the component are sliced together with the shell, the plurality of independent paths of each slice are sequentially connected at the beginning and the end, the accumulation layer is formed in one time in the circumferential direction, the number of arc breakage in the electric arc additive manufacturing process is greatly reduced, and the problems of arc gun interference and shell melting through, which occur when the shell is formed first and then the rib plate is accumulated in the shell, are effectively avoided, the forming quality and efficiency of the component are significantly improved, and thus the present application has a broad application prospect.

[0222] Those skilled in the art will readily understand that the above description is only preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An arc additive manufacturing method for a thin-walled aluminum alloy shell with longitudinal internal stiffeners, characterized in that, The thin-walled shell has multiple irregular longitudinal inner stiffening plates that are perpendicular to the end face and distributed along the generatrix of the shell. The method includes the following steps: (a) Modeling and establishing a reference coordinate system In this step, a corresponding three-dimensional model of the aluminum alloy thin-walled shell with longitudinal internal stiffeners to be manufactured is established, and a reference coordinate system containing the XYZ axes is set. (b) The overall slicing procedure of the longitudinal inner stiffening plate along with the shell In this step, all longitudinal inner stiffeners, together with the shell, are sliced ​​along the Z-axis direction, which is parallel to the shell axis, to obtain a slice profile composed of the outer contour and the inner contour. (c) Initialization steps for slice contour paths In this step, for the outer and inner contour paths corresponding to the outer and inner contours respectively, the set of position points contained therein is traversed and sorted according to the minimum value of the X-axis coordinate, and arranged in a clockwise direction, thereby obtaining the initialized outer and inner contour paths. (d) Steps for extracting the main shape path In this step, for the shell, the initialized outer contour path is offset inward by a certain distance, and the new outer contour is extracted, which is the main shape path of the shell. For each longitudinal inner stiffener, the initialized inner contour path is offset outward by the corresponding distance, and the inner contour is extended to intersect with the new outer contour of the shell. The non-closed area between the intersection points is the main shape path of each longitudinal inner stiffener. (e) Rearrangement steps of the main shape path In this step, the main shape path of the shell is divided into multiple parts by the intersection point, and these multiple parts are arranged in a clockwise direction. At the same time, the main shape paths of each longitudinal inner stiffener are closed in a clockwise direction, thereby completing the rearrangement of the main shape path. (f) Steps for planning the filling path of the longitudinal internal stiffening plate In this step, the main shape path of each longitudinal inner stiffener is taken out in a clockwise direction, and the stacking path is planned according to these main shape paths, thereby obtaining the stacking path of each longitudinal inner stiffener. (g) Forming a closed-loop deposition path and arc additive manufacturing steps In this step, the main shape path of the shell after step (e) is connected end to end in a clockwise direction with the stacking paths of all longitudinal internal stiffeners to obtain the final closed-loop stacking path. Based on this final closed-loop deposition path, an electric arc additive manufacturing process is used to form each deposition layer circumferentially in one step until the desired aluminum alloy thin-walled shell with longitudinal internal stiffeners is obtained.

2. The arc additive manufacturing method as described in claim 1, characterized in that, In step (b), the initial slice height is set to 0.2 mm to 0.5 mm; starting from the second slice, the slice height is set to 70% to 90% of the single-pass deposited metal height.

3. The electric arc additive manufacturing method as described in claim 2, characterized in that, In step (d), for the shell, its initialized outer contour path is offset inward by 1 / 2 the shell thickness; for each longitudinal inner stiffener, its initialized inner contour path is offset outward by 1 / 2 the shell thickness, and the inner contour is extended to intersect with the new outer contour of the shell.

4. The electric arc additive manufacturing method as described in claim 3, characterized in that, In step (f), for the main shape path of each longitudinal inner stiffener, a stacking path planning process involving single-path, offset, and scanning is performed simultaneously.

5. The electric arc additive manufacturing method as described in claim 4, characterized in that, In step (f), the width of the single-pass stacked metal is designed using the following formula: shell thickness + 2 * single-side machining allowance.

6. The arc additive manufacturing method as described in claim 5, characterized in that, In step (f), the single-sided machining allowance is 1.5mm to 3mm, and the overlap is 25% to 42% of the width of the single-pass stacked metal.

7. The electric arc additive manufacturing method according to any one of claims 1-6, characterized in that, In step (g), the wire and substrate used in the arc additive manufacturing process are both aluminum alloys, and the protective gas is high-purity Ar with a flow rate of 20 L / min to 25 L / min.

8. The electric arc additive manufacturing method as described in claim 7, characterized in that, In step (g), the following multiple process windows are used for manufacturing: Process 1: Stacking current 150A~183A, stacking voltage 22V~24V, stacking speed 0.7 mm / min~1.0 mm / min; Process 2: Stacking current 100A~136A, stacking voltage 20V~22V, stacking speed 0.5mm / min~0.8mm / min; Process 3: Stacking current 180A~210A, stacking voltage 25V~26V, stacking speed 0.6mm / min~0.9mm / min.

9. A thin-walled aluminum alloy shell with longitudinal internal stiffeners, characterized in that, It is prepared by means of any one of claims 1-8.

Images