A high-precision additive manufacturing method for open thin-walled cabin sections

Abstract

The application discloses a kind of high-precision additive manufacturing methods of open thin-walled cabin section, belong to additive manufacturing technical field.The method is set as with the middle part of open structure as bottom to the direction of additive manufacturing, and do grid-shaped strong constraint;The two end faces of open are closed, and open cabin section is converted into nearly closed cabin section;With the shape design sandwich structure of two side thin-walled structures, the two side walls of weak rigidity are converted into stable sandwich structure;Four corners are designed to extend support rib plate.The above-mentioned shape structure is removed after stress relief heat treatment, and finally the high-precision additive manufacturing open thin-walled cabin section product is obtained.The open structure is converted into more stable closed structure in the application, and with the aid of sandwich design, the risk of structural deformation is greatly reduced, and there is no need to additionally manufacture shape correction tooling;The support structure such as bottom grid and rib plate is hollowed out, which guarantees the high-precision shape level of formed product while reducing cost investment.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, and in particular relates to a high-precision additive manufacturing method for an open thin-walled compartment. Background Technology

[0002] Additive manufacturing is a rapidly developing manufacturing technology in recent years. Based on digital models, it obtains processing programs through layer slicing, path planning, etc., and directly forms structural parts by adding materials layer by layer. It has advantages such as no need for molds, high efficiency, and low development cost, and has been widely used in high-end manufacturing fields such as aerospace in recent years.

[0003] With the development of advanced manufacturing technologies, the structural forms of compartment components are becoming increasingly complex, and their wall thicknesses are becoming increasingly thinner. Traditional compartment structures are mostly closed circular, square, or polygonal bodies with closed cross-sections, and their structural shape remains relatively stable throughout the production process. However, to meet the requirements of certain assembly and operational conditions, some new compartment structures are designed as modular, open-type compartments, manufactured separately and then assembled. A typical open-type thin-walled compartment structure is as follows: Figure 1 As shown, its shape is open in at least two directions, and the wall thickness X is generally ≤3mm. Such split, open, thin-walled compartments often have thin walls, numerous features, and complex structures, and require high surface precision in practical use. To meet the needs of rapid development, additive manufacturing can be used to form new open, thin-walled compartments. However, because additive manufacturing involves the accumulation of thermal stress layer by layer, it can easily cause large deformations or even cracks in open, thin-walled structures.

[0004] In the deformation control of additively manufactured compartment products, methods such as rib and lattice shaping, pre-reverse deformation, and thermal correction can be used to improve their surface accuracy. Rib and lattice shaping and pre-reverse deformation methods are effective for regular, closed compartments, but open, thin-walled compartments exhibit extreme deformation tendencies. Using only ribs and lattices for structural shape control is ineffective, and pre-reverse deformation is difficult to implement under large deformations. Furthermore, open, thin-walled compartment structures have low structural stability, experiencing large deformations not only during the additive manufacturing process but also in unpredictable deformations during subsequent heat treatment and support removal. Therefore, traditional rib and lattice shaping and pre-reverse deformation methods cannot achieve high-precision manufacturing of such structural components. While thermal correction can theoretically improve the surface accuracy of compartments, developing corresponding correction tooling is time-consuming and costly, generally failing to meet development and usage requirements. Therefore, there is currently no effective high-precision additive manufacturing method for open, thin-walled compartment structures. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of existing technologies and provide a high-precision additive manufacturing method for open-type thin-walled compartments. This method transforms the open structure into a more stable closed structure, and through a sandwich design, converts the weakly rigid thin-walled structure into a more rigid sandwich structure. This significantly improves structural rigidity and greatly reduces the risk of cracking and deformation during additive manufacturing and heat treatment.

[0006] The technical solution of this invention is:

[0007] A high-precision additive manufacturing method for an open, thin-walled compartment section includes the following steps:

[0008] Step 1: Select the additive manufacturing direction of the additive manufacturing model with the middle part of the open structure as the bottom, and apply strong grid-like constraints to the bottom part. The resulting bottom grid serves as the bottom support.

[0009] Step 2: Seal off the two open end faces. After sealing, the open section is transformed into a near-closed section.

[0010] Step 3: Design a conformal sandwich-shaped support structure for the thin-walled structures on both sides to transform the relatively weak side walls into a stable sandwich structure.

[0011] Step 4: Design extended support ribs at the four corners;

[0012] Step 5: Design the bottom grid from Step 1, the closed structure from Step 2, the conformal sandwich-shaped support structure from Step 3, and the extended support ribs from Step 4 into an additive self-forming hollow structure.

[0013] Step Six: Add additive overhang support to the designed additive manufacturing model, and then perform additive manufacturing.

[0014] Step 7: After the additive manufacturing is completed, stress-relief annealing is performed according to the usage requirements. Then, the bottom grid, two conformal sandwich-like dimensional support structures, and four corner extended support ribs are cut off along the outer contour of the product. Finally, the remaining support structures are removed to obtain a high-precision additively manufactured open thin-walled compartment product.

[0015] Preferably, in step one, the wall thickness of the bottom mesh body is (2 to 4) times the wall thickness of the middle part of the additive manufacturing model, and the connection part with the additive manufacturing model is thinned to (0.5 to 1) times the wall thickness of the middle part of the model.

[0016] Preferably, in step two, when closing the open two ends, if a sealing plate is used for closure, the thickness of the sealing plate is (3 to 5) times the wall thickness of the additive manufacturing model body; if a lattice is used for closure, the overall thickness of the lattice is (0.1 to 0.2) times the distance between the two ends.

[0017] Preferably, in step three, the conformal sandwich-shaped support structure comprises three parts: a conformal outer plate, a sandwich rib plate with its inner side perpendicular to the model surface, and an internal filling sandwich structure; the conformal outer plate is a plate-like structure whose shape conforms to the shape of the thin walls on both sides and rests on the additive substrate; the sandwich rib plate is uniformly distributed on the thin walls on both sides and forms a normal angle with the surface of the thin walls, connecting the side walls of the model to the conformal outer plate; the internal filling sandwich structure is a lattice or grid-shaped rib plate.

[0018] Preferably, in step four, the height of the four corner extended support ribs is consistent with the height of the model at the location, and the ends are designed as square or round solid columns.

[0019] Preferably, in step five, the self-formed hollow structure is circular or rhomboid.

[0020] Preferably, the additive manufacturing method is applicable to the additive manufacturing of elliptical parts made of any alloy material.

[0021] Preferably, the additive manufacturing method is applicable to high-precision additive manufacturing of open thin-walled compartments using various additive manufacturing processes.

[0022] Preferably, the additive manufacturing process includes laser selective melting, electron beam selective melting, photopolymerization, and direct energy deposition.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) Based on the structural characteristics of open thin-walled structures, this invention transforms the open structure into a more stable closed structure through a three-dimensional support structure design, and transforms the weakly rigid thin-walled structure into a more rigid sandwich structure through a sandwich design. This significantly improves the structural rigidity and greatly reduces the risk of cracking and deformation during additive manufacturing and heat treatment.

[0025] (2) The sealing plate, sandwich rib and other structures used in this invention can be integrated with the part body for additive manufacturing, without the need to make additional correction and shaping tooling, so as to achieve a better surface accuracy control effect.

[0026] (3) In addition to its shape control function in the additive manufacturing process, the end face sealing plate used in this invention can also play a shape control role in subsequent heat treatment and machining processes, which can reduce the use of tooling in subsequent processing and ensure the shape accuracy of the final delivered product.

[0027] (4) The main interlayer support structure of the present invention has a simple form and can be quickly removed by cutting processing methods, ensuring the efficiency of the support removal process. At the same time, considering the need for cost reduction and efficiency improvement in actual production, the present invention hollows out the bottom grid, ribs and other support structures while improving the manufacturing rigidity, thereby reducing cost input while ensuring the high precision of the surface of the formed product. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an open, thin-walled compartment structure.

[0029] Figure 2 This is a flowchart of the present invention;

[0030] Figure 3 This is a schematic diagram of the dimensions of an open, thin-walled compartment as an example.

[0031] Figure 4 This is a diagram of a dimensional support structure designed according to the method of the present invention in an embodiment;

[0032] Figure 5 This is a schematic diagram of a thinning structure designed according to the method of the present invention in an embodiment;

[0033] Figure 6 The deformation result is obtained from direct additive manufacturing in the example.

[0034] Figure 7 The example shows the additive manufacturing deformation result after shape control according to the method of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0036] For open-type thin-walled compartments, due to their weak structural rigidity and instability, cracking and large deformation are common during selective laser melting additive manufacturing under significant internal stress, making high-precision manufacturing difficult. This invention proposes a high-precision additive manufacturing method for open-type thin-walled compartments. The additive manufacturing direction is set with the middle part of the open structure as the base, and a grid-like strong constraint is used to connect it to the bottom support. The open end faces are sealed using end plates, lattice structures, etc., transforming the open compartment into a near-closed compartment. Furthermore, a sandwich-like dimensional support structure is designed to conform to the shape of the thin-walled structures on both sides, transforming the weak side walls into a stable sandwich structure. Finally, extended support ribs are designed at the four corners to distribute stress concentration and large deformation to the extended support ribs. The aforementioned dimensional structure is removed after stress-relief heat treatment using wire cutting, grinding, etc., ultimately yielding a high-precision additively manufactured open-type thin-walled compartment product.

[0037] This invention discloses a high-precision additive manufacturing method for an open, thin-walled compartment, according to... Figure 2 Follow the steps shown.

[0038] Step 1: Select the additive manufacturing direction for the additive manufacturing model: use the middle part of the open structure as the bottom. Apply a strong grid-like constraint to this bottom part as a bottom support to ensure the stability of the bottom structure.

[0039] The size of each grid is between (20×20) and (100×100) mm. The thickness of the main body wall is (2 to 4) times the thickness of the wall in the middle of the model, and the thickness of the part connected to the model is reduced to (0.5 to 1) times the thickness of the wall in the middle of the model.

[0040] Step 2: The open end faces are sealed using structures such as sealing plates and dot matrix, at which point the open section is transformed into a near-closed section.

[0041] If a sealing plate is used for closure, the thickness of the sealing plate is (3 to 5) times the thickness of the main body wall of the model; if a lattice is used for closure, the overall thickness of the lattice is (0.1 to 0.2) times the distance between the two end faces, the lattice cell size is (0.2 to 0.5) times the overall thickness of the lattice, and the lattice rod diameter is (0.5 to 0.8) times the thickness of the main body wall of the model.

[0042] Step 3: Design a sandwich-shaped support structure for the thin-walled structures on both sides to transform the relatively weak side walls into a stable sandwich structure.

[0043] The conformal sandwich-shaped support structure consists of three parts: a conformal outer plate, an inner sandwich rib perpendicular to the model surface, and an internal filling sandwich structure.

[0044] The conformal outer plate is located at a distance of (15-30) mm from the side wall, and its thickness is (2-4) times the thickness of the main body wall of the model. Its shape is a plate-like structure that approximates the shape of thin walls on both sides and rests on the additive substrate.

[0045] The sandwich ribs are evenly distributed on the sidewalls and are at a normal angle to the sidewall surface. They connect the sidewalls of the model to the conformal outer plate. The thickness is (1 to 2) times the thickness of the main body wall of the model. At the connection with the model, the thickness is reduced to (0.5 to 0.9) times the thickness of the main body wall of the model.

[0046] The internal filling sandwich structure can be either a lattice or a mesh-shaped rib. If a lattice is used, the lattice cell size is (0.2 to 0.5) times the overall thickness of the lattice, and the lattice rod diameter is (0.5 to 0.8) times the thickness of the main body wall of the model. If a mesh-shaped rib is used, the mesh can be various polygons such as rhombuses and hexagons, with a thickness of (0.5 to 0.8) times the thickness of the main body wall of the model, and at a normal angle to the side wall surface.

[0047] Step 4: Design extended support ribs at the four corners to distribute stress concentration and large deformation to the extended support ribs.

[0048] The height of the four corner extended support ribs is consistent with the height of the model at their location, and the thickness is (1.5 to 3) times the thickness of the main body wall of the model. The ends are designed with square or circular solid columns to further distribute stress. The side length of the square solid column is (2 to 4) times the thickness of the support rib; the diameter of the circular solid column is (2 to 4) times the thickness of the support rib.

[0049] Step 5: Design additive self-forming hollow structures for the bottom grid, ribs, dot matrix, and other dimensional supports. This reduces the weight of additive manufacturing materials, improves production efficiency, and lowers production costs. Self-forming hollow structures include circular, rhomboid, and other hollow structure forms.

[0050] Step Six: After adding additive overhanging surface support to the designed model, perform additive manufacturing to form the model.

[0051] Step 7: After additive manufacturing is completed, stress-relief annealing is performed according to usage requirements. Then, the bottom mesh, two interlayer supports, and four corner extension support ribs are cut along the product's outer contour using wire cutting or manual cutting. Finally, residual support structures are removed using grinding and machining, resulting in a high-precision additively manufactured open-type thin-walled compartment product.

[0052] This invention is applicable to additive manufacturing of elliptical parts made of any material, such as titanium alloys, high-temperature alloys, and aluminum alloys.

[0053] This invention is applicable to high-precision additive manufacturing of open-type thin-walled compartments using various additive manufacturing processes such as laser selective melting, electron beam selective melting, photopolymerization, and direct energy deposition.

[0054] Example:

[0055] like Figure 3 As shown, the embodiment is an open, thin-walled compartment made of titanium alloy. It is 300mm long, has a U-shaped cross-section with a radius of R150mm for the arc portion, a width of 300mm, a height of 350mm, and a wall thickness of 2mm. The model designed according to the method of this invention is shown below. Figure 4 As shown, the specific operations are as follows:

[0056] Step 1: Select the additive manufacturing direction for the additive manufacturing model: use the middle part of the open structure as the base, that is, the arc part of the "U" shaped cross-section in the embodiment as the base. Create a strong grid-like constraint on this base area to connect it to the bottom support, ensuring the stability of the base structure.

[0057] The bottom mesh 1 is set to a size of (80×100) mm, with a mesh wall thickness of 5 mm. The thickness at the connection point with the model is reduced to 1.5 mm, and the thinning structure is as follows: Figure 5 As shown.

[0058] Step 2: The two ends of the open thin-walled section are sealed with a dot matrix, thus transforming the open section into a near-closed section.

[0059] The thickness of each of the two lattice regions is 20mm, meaning the overall thickness is 40mm. The lattice cell size is 10mm, and the lattice rod diameter is 1mm.

[0060] Step 3: Design a sandwich-shaped support structure for the thin-walled structures on both sides to transform the relatively weak side walls into a stable sandwich structure.

[0061] The conformal sandwich-shaped support structure consists of three parts: a conformal outer plate 3, an inner sandwich rib plate 4 perpendicular to the model surface, and an internal filling sandwich structure 5.

[0062] The conformal outer layer is located 20mm from the sidewall, has a thickness of 4mm, and is a plate-like structure parallel to the shape of the thin walls on both sides, and is connected to the additive substrate.

[0063] The sandwich rib is perpendicular to the side wall of the product and connects the side wall of the model to the conformal outer plate. It has a thickness of 3mm, and the thickness is reduced to 1.5mm at the connection with the model.

[0064] The internal filling sandwich structure is designed with diamond-shaped mesh ribs, 1mm thick, and at a normal angle to the side wall surface.

[0065] Step 4: Design extended support ribs at the four corners to distribute stress concentration and large deformation to the extended support ribs.

[0066] The height of the four corner extended support ribs 6 is consistent with the height of the model at the location, and the thickness is 3mm. The ends are designed with circular solid columns to further disperse stress. The diameter of the circular solid columns is 6mm.

[0067] Step 5: Design additive self-forming hollow structures for the bottom grid, ribs, dot matrix, and other dimensional supports. This reduces the weight of additive manufacturing materials, improves production efficiency, and lowers production costs. Self-forming hollow structures include circular, rhomboid, and other hollow structure forms.

[0068] Step Six: After adding additive overhanging supports to the designed model, additive manufacturing is performed. Before additive manufacturing, the deformation results of additive manufacturing using the original model and additive manufacturing using the method of this invention were simulated. The results are as follows: Figure 6 and Figure 7 As shown in the figure, it can be seen that after adopting the method of the present invention, the large deformations in various parts of the original compartment were completely eliminated, and the maximum local deformation was reduced from 13mm to less than 0.3mm.

[0069] Step 7: After forming, stress-relief annealing is performed to remove internal stress from the product. Then, the bottom mesh, two sandwich supports, and four corner extension support ribs are cut off along the outer contour of the product using wire cutting or manual cutting. Finally, residual support structures are removed by grinding and machining, resulting in a high-precision additively manufactured open thin-walled compartment product.

[0070] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0071] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-precision additive manufacturing method for an open-type thin-walled compartment, characterized in that, Includes the following steps: Step 1: Select the additive manufacturing direction of the additive manufacturing model with the middle part of the open structure as the bottom, and apply strong grid-like constraints to the bottom part. The resulting bottom grid serves as the bottom support. Step 2: Seal off the two open end faces. After sealing, the open section is transformed into a near-closed section. Step 3: Design a conformal sandwich-shaped support structure for the thin-walled structures on both sides to transform the relatively weak side walls into a stable sandwich structure. Step 4: Design extended support ribs at the four corners; Step 5: Design the bottom grid from Step 1, the closed structure from Step 2, the conformal sandwich-shaped support structure from Step 3, and the extended support ribs from Step 4 into an additive self-forming hollow structure. Step Six: Add additive overhang support to the designed additive manufacturing model, and then perform additive manufacturing. Step 7: After the additive manufacturing is completed, stress-relief annealing is performed according to the usage requirements. Then, the bottom grid, two conformal sandwich-like dimensional support structures, and four corner extended support ribs are cut off along the outer contour of the product. Finally, the remaining support structures are removed to obtain a high-precision additively manufactured open thin-walled compartment product.

2. The high-precision additive manufacturing method for an open-type thin-walled compartment according to claim 1, characterized in that, In step one, the wall thickness of the bottom mesh body is (2 to 4) times the wall thickness of the middle part of the additive manufacturing model, and the connection part with the additive manufacturing model is thinned to (0.5 to 1) times the wall thickness of the middle part of the model.

3. The high-precision additive manufacturing method for an open thin-walled compartment according to claim 1, characterized in that, In step two, when closing the open end faces, if a sealing plate is used, the thickness of the sealing plate is (3 to 5) times the wall thickness of the additive manufacturing model body; if a lattice is used, the overall thickness of the lattice is (0.1 to 0.2) times the distance between the two end faces.

4. The high-precision additive manufacturing method for an open thin-walled compartment according to claim 1, characterized in that, In step three, the conformal sandwich-shaped support structure comprises three parts: a conformal outer plate, a sandwich rib plate with its inner side perpendicular to the model surface, and an internal filling sandwich structure. The conformal outer plate is a plate-like structure whose shape conforms to the shape of the thin walls on both sides and rests on the additive substrate. The sandwich rib plate is evenly distributed on the thin walls on both sides and forms a normal angle with the surface of the thin walls, connecting the side walls of the model to the conformal outer plate. The internal filling sandwich structure is a lattice or grid-shaped rib plate.

5. The high-precision additive manufacturing method for an open-type thin-walled compartment according to claim 1, characterized in that, In step four, the height of the four corner extended support ribs is consistent with the height of the model at the location, and the ends are designed as square or round solid columns.

6. The high-precision additive manufacturing method for an open thin-walled compartment according to claim 1, characterized in that, In step five, the self-formed hollow structure takes the form of a circle or a rhombus.

7. The high-precision additive manufacturing method for an open-type thin-walled compartment according to claim 1, characterized in that, The additive manufacturing method described herein is applicable to the additive manufacturing of elliptical parts made of any alloy material.

8. The high-precision additive manufacturing method for an open thin-walled compartment according to claim 1, characterized in that, The additive manufacturing method described herein is applicable to high-precision additive manufacturing of open-type thin-walled compartments using various additive manufacturing processes.

9. A high-precision additive manufacturing method for an open-type thin-walled compartment according to claim 8, characterized in that, The additive manufacturing processes include selective laser melting, selective electron beam melting, photopolymerization, and direct energy deposition.

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