A lightweight integrated multi-cavity structural component additive manufacturing method

Abstract

The application provides a lightweight integrated multi-cavity structure part additive manufacturing method, first, a forming direction is selected, and a self-forming structure is designed on a process model design for a partition structure between cavities, so that integrated multi-cavity forming is realized. Further, the requirements of product integration and lightweight are considered, and an integrated pipeline based on topology optimization, a self-forming rib and a rib plate or a variable density point array structure for supporting an internal overhang or a surface that cannot be self-formed are designed. In order to consider the cleaning and detection of excess materials, a process hole structure that is interconnected and connected to the outside is designed at the lowest point in the forming direction of each cavity, so that the lightweight integrated multi-cavity structure additive process model design is completed. After additive manufacturing is completed according to the selected forming direction, the residual powder, liquid and other excess materials are completely removed by means of the designed process hole, and finally, the lightweight integrated multi-cavity structure additive manufacturing is realized.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, and particularly relates to an additive manufacturing method for a lightweight integrated multi-cavity structural component. Background Technology

[0002] With the development of additive manufacturing technology, the technique of manufacturing one-piece structural parts using the "additive material forming" characteristic of additive manufacturing has been widely applied. One-piece formed structural parts generally have a single cavity, within which functional structures such as pipes and ribs can be integrated. To further leverage the advantages of "one-piece" forming in additive manufacturing, it is possible to integrate components with multiple cavities to form a single one-piece part. However, when a structural part has multiple cavities, factors such as numerous overhangs in the additive forming direction and poor cavity connectivity lead to an increase in the weight of the formed structural part, making it difficult to remove excess material and significantly increasing the difficulty of additive manufacturing.

[0003] To address these issues and improve the quality of complex structures formed by selective laser melting (SLM), CN 117773152A, "Detailed Optimization Design Method for Multi-Ring, Multi-Cavity, Thin-Walled Complex Structural Parts Formed by Selective Laser Melting," proposes detailed optimization design of features such as reinforcing ribs, right angles or sharp corners, thin walls, small gaps, and closed cavities. This reduces stress concentration in these areas during SLM, thereby preventing deformation and cracking and improving the quality of the formed parts. However, these detailed optimizations only ensure successful forming of the structural parts. For additive manufacturing of integrated multi-cavity structures, they cannot solve the problems of difficult cleaning of powder, liquid, and other foreign matter from the internal cavities of the formed parts, or the significant weight increase caused by suspended surface supports or self-forming structures. Therefore, for integrated multi-cavity structural parts, there is currently no effective additive manufacturing method that can simultaneously achieve lightweighting, forming quality, and foreign matter control. Summary of the Invention

[0004] The technical problem solved by the present invention is to overcome the shortcomings of the prior art and provide a lightweight integrated multi-cavity structural component additive manufacturing method.

[0005] The technical solution of this invention is:

[0006] A method for additive manufacturing of a lightweight, integrated multi-cavity structural component includes the following steps:

[0007] Step 1: Design the partitioned structure between cavities that are suspended or have insufficient forming angle in the forming direction into a self-forming structure, while maintaining its function of dividing the cavity area, so as to realize the direct forming of multiple cavities in one piece;

[0008] Step 2: Design an integrated pipeline based on topology optimization, connecting it to the surrounding structure using the least amount of material; the topology optimization method is as follows: connect the bottom surface of the pipeline in the forming direction to the surrounding structure to form a connecting plate, set the design input as the structural warping stress on the plate, the connection surface with the surrounding structure as the fixed surface, the non-calculation threshold as the perimeter area of ​​the plate, the calculation threshold as the center area of ​​the plate, the topology algorithm as the maximum rigidity, the material reduction amount as (50~70)%, and the perimeter area of ​​the plate as the boundary of the plate offset inward by (1~5) mm;

[0009] Step 3: Design the self-forming ribs according to the self-forming angle in Step 1;

[0010] Step 4: Design a support structure below the structure that cannot be self-formed inside the cavity. The support structure is a self-forming rib or a variable density lattice, and the support structure is retained after the structural component is manufactured.

[0011] Step 5: Design at least one interconnected process hole structure at the lowest point of each cavity forming direction to connect the multi-cavity structures; design at least one process hole communicating with the outside at the lowest point of the interconnected multi-cavity structures in the forming direction for the discharge of internal waste; design at least one process hole structure communicating with the outside at the top surface of each cavity communicating with the outside in the forming direction for the cleaning and inspection of waste.

[0012] Step 6: Add necessary supports to the outside of the structural component according to the selected forming direction. The added supports should not block the designed process hole structure that connects with the outside world. Complete the additive manufacturing process model design.

[0013] Step 7: Complete the additive manufacturing process according to the additive manufacturing process selected in Step 1;

[0014] Step 8: After completing the additive manufacturing process, use the process hole structure designed in Step 5 to thoroughly clean the remaining foreign matter inside.

[0015] Step 9: Continue with subsequent drying, heat treatment, support removal, grinding, and machining processes to achieve additive manufacturing of a lightweight, integrated multi-cavity structure.

[0016] Preferably, the self-forming structure includes, but is not limited to: an inclined plate at a certain angle to the horizontal direction, and a "pyramid" shaped plate.

[0017] Preferably, in step two, if the outer diameter of the integrated pipeline is R, then the thickness of the connecting plate is 1 / 3R to R.

[0018] Preferably, in step three, if the self-forming rib is a hollow rib, it must be ensured that each independent cavity space has at least one hole / groove structure that communicates with the outside.

[0019] Preferably, in step three, the outer contour of the self-forming rib is triangular, the upper surface is in contact with the supported structure, and the distance from the edge of the structure is (1~5) mm; the side is in contact with the adjacent self-forming surface; the angle of the inclined side is designed according to the self-forming angle in step one.

[0020] Preferably, the self-forming rib is based on a topology optimization design for a hollow structure. The topology optimization method is as follows: the design input is the structural warping stress borne by the surface of the triangular rib, the non-calculation threshold is the perimeter area of ​​the triangular rib, the calculation threshold is the center area of ​​the triangular rib, the topology algorithm is the maximum rigidity, the material reduction is (50-70)%, and the perimeter area of ​​the rib is the boundary of the rib offset inward by (1-4) mm.

[0021] Preferably, in step five, the shape of the process hole includes circular, semi-circular, and rectangular.

[0022] Preferably, the method for inspecting foreign matter using the process hole structure includes, but is not limited to, endoscopic inspection and visual inspection.

[0023] Preferably, in step one, the self-forming angle refers to the angle between the structure and the horizontal plane where the additive forming is located.

[0024] Preferably, in step eight, cleaning the internal residue includes: high-pressure gas cleaning, high-pressure liquid flushing, and liquid rinsing; during the cleaning process, X-ray or endoscopic examination is used to check the condition of the internal residue in real time until the residue is completely cleaned.

[0025] The gas includes air and inert gas; the liquid includes water, anhydrous ethanol, acetone, gasoline, and special cleaning agents.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) This invention takes into account both the additive manufacturing process and the functionality of the structural parts. Based on the additive manufacturing direction, it designs the partition, pipeline and other structures to achieve the integrated forming of multi-cavity structures, thereby significantly reducing the number of parts in complex structural parts and improving product development efficiency.

[0028] (2) Based on integrated molding, this invention takes into account structural weight. In the design of pipelines, ribs and internal support structures without removing them, extreme lightweighting is achieved based on topology optimization, which retains functionality while minimizing weight.

[0029] (3) Based on the integrated molding effect, this invention can effectively solve the problem of difficult removal and detection of foreign matter inside multi-cavity structures. Through the design of process holes and the method of cleaning and detecting after molding, the foreign matter can be completely removed to meet the needs of engineering applications. Attached Figure Description

[0030] Figure 1 This is a flowchart of the present invention;

[0031] Figure 2 This is a schematic diagram of an open, thin-walled compartment as an example.

[0032] Figure 3 This is a schematic diagram of an integrated multi-cavity structure for an embodiment.

[0033] Figure 4 This is a schematic diagram of the internal structure designed according to the method of the present invention in an embodiment;

[0034] Figure 5 This is a schematic diagram illustrating the process of designing a pipeline structure according to the method of the present invention in an embodiment.

[0035] Figure 6 This is a schematic diagram of a self-forming rib structure designed according to the method of the present invention in an embodiment;

[0036] Figure 7 This is a schematic diagram of the rib spacing dimensions designed according to the method of the present invention in an embodiment;

[0037] Figure 8 This is a schematic diagram illustrating the process of designing a rib according to the method of the present invention in an embodiment. Detailed Implementation

[0038] 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.

[0039] This invention discloses an additive manufacturing method for a lightweight, integrated multi-cavity structural component, such as... Figure 1 As shown, it includes the following steps:

[0040] Step 1: Design a self-forming structure for the partitioned structure between multiple cavities. Specifically, design a self-forming structure for the partitioned structure between cavities that are suspended or have insufficient forming angles in the forming direction, while maintaining its function of dividing the cavity areas. The self-forming angle is determined according to the forming process and material selection. Self-forming structures include, but are not limited to: inclined plates at a certain angle to the horizontal direction, "pyramid" shaped plates, etc.

[0041] The forming processes include: powder bed sintering / melting additive manufacturing, direct deposition additive manufacturing, photopolymerization additive manufacturing, etc.

[0042] The self-forming angle refers to the angle between the structure and the horizontal plane where the additive manufacturing process takes place. For powder bed sintering processes, it is generally ≥30°; for powder bed melting processes, it is generally: ≥45° for aluminum alloys and titanium alloys, and ≥55° for high-temperature alloys and alloy steels; for direct deposition additive manufacturing processes, it is generally ≥45° for aluminum alloys, and ≥45° for titanium alloys, high-temperature alloys, and alloy steels; for photopolymerization additive manufacturing, it is generally ≥30°.

[0043] Step 2: Design an integrated piping system based on topology optimization. Existing piping installations typically have fixed shapes and orientations based on functionality. Following the principle of self-forming additive manufacturing, topology optimization is performed to connect the piping to surrounding structures using minimal materials.

[0044] The topology optimization method is as follows: the bottom surface of the pipeline forming direction is connected to the surrounding structure of the product to form a plate. The design input is set as the plate bearing the structural warping stress, the connection surface with the surrounding structure is a fixed surface, the non-calculation threshold is the perimeter area of ​​the plate, the calculation threshold is the center area of ​​the plate, the topology algorithm is the maximum rigidity, the material reduction is (50~70)%, and the perimeter area of ​​the plate is the boundary of the plate offset inward by (1~5) mm.

[0045] Step 3: Design self-forming ribs. The self-forming ribs should be designed according to the self-forming angle principle described in Step 1. If designing hollow ribs, it must be ensured that each independent cavity space has at least one hole / groove structure communicating with the outside, and the cross-sectional area of ​​the hole / groove structure must be ≥3mm². 2 .

[0046] Step 4: Design self-forming ribs or variable-density lattices below the structures inside the cavity that cannot yet self-form, as their supporting structure, and retain them as part of the structure after its manufacturing is completed. The distance between the self-forming ribs or variable-density lattices and the solid structures in contact with the supported surfaces is (1-6) mm. The outer contour of the self-forming rib is triangular, with the upper surface in contact with the supported structure at a distance of (1-5) mm from the edge of the structure; the side is in contact with the adjacent self-forming surface; the angle of the hypotenuse is designed according to the self-forming angle described in Step 1. The rib is designed with a hollow structure based on topology optimization. The topology optimization method is as follows: the design input is set as the structural warping stress borne by the upper surface of the triangular rib, the non-calculation threshold is the perimeter area of ​​the triangular plate, the calculation threshold is the center area of ​​the plate, the topology algorithm is maximum rigidity, the material reduction is (50-70)%, and the perimeter area of ​​the plate is the boundary of the plate offset inward by (1-4) mm.

[0047] Step 5: Design at least one interconnected process hole structure at the lowest point of each cavity forming direction to connect the multi-cavity structures; design at least one process hole communicating with the outside at the lowest point of each interconnected multi-cavity structure forming direction for the discharge of internal waste. Design at least one process hole structure communicating with the outside at the top surface of each cavity communicating with the outside in the forming direction for the cleaning and inspection of waste.

[0048] The cross-sectional area of ​​the process holes connecting each cavity is ≥3mm². 2 The cross-sectional area of ​​the process hole connecting the cavity to the outside is ≥10mm². 2 The shapes of the process holes include circles, semicircles, rectangles, etc.

[0049] The methods for inspecting for foreign matter using process hole structures include endoscopic examination and visual inspection.

[0050] Step Six: Add necessary supports to the outside of the structural component according to the selected forming direction. The added supports should not block the designed process hole structure that connects with the outside world. Complete the additive manufacturing process model design.

[0051] Step 7: Complete the additive manufacturing process according to the additive manufacturing process selected in Step 1.

[0052] Step 8: After additive manufacturing is completed, the process hole structure designed in Step 5 is used to thoroughly clean the internal residues of powder, liquid, and other foreign matter. The cleaning methods include: high-pressure gas cleaning, high-pressure liquid flushing, and liquid rinsing. The high-pressure gas includes air and inert gas. The liquid includes water, anhydrous ethanol, acetone, gasoline, and specialized cleaning agents. During the cleaning process, X-ray and endoscopic examinations are used to monitor the internal cavity for any remaining foreign matter until it is completely removed.

[0053] Step 9: Continue with subsequent drying, heat treatment, support removal, grinding, and machining processes to achieve additive manufacturing of a lightweight, integrated multi-cavity structure.

[0054] Example:

[0055] like Figure 2 As shown, the embodiment is an open, thin-walled compartment made of aluminum alloy, manufactured using laser selective melting additive manufacturing. The smaller cross-section is selected as the bottom, and additive manufacturing is performed from bottom to top. The length in the additive manufacturing direction is 600 mm, and the cross-section in the forming direction is a rectangle of 200 × 200 mm. The model designed according to the method of this invention is shown below. Figure 3 As shown, the specific operations are as follows:

[0056] Step 1: Design a self-forming structure for the partitioned structure 1-1 lower horizontal plate, 1-2 upper horizontal plate, and 1-3 vertical plate between the multi-cavity sections. Based on the materials and process methods of aluminum alloy powder bed melting, select a self-forming angle of 45°.

[0057] The lower horizontal plate 1-1 is designed as a pyramid-shaped structure, with each face making a 45° angle with the horizontal plane, resulting in the optimized lower horizontal plate 2-1. The upper horizontal plate 1-2 is designed as two inclined plates, each face making a 45° angle with the horizontal plane, resulting in the optimized lower horizontal plate 2-2. The vertical plate 1-3 satisfies the self-forming condition, therefore the original structure remains unchanged, and the vertical plate 2-3 is the same as the vertical plate 1-3.

[0058] Step 2: Design the 1-4 pipe structure as an integrated pipe system based on topology optimization, as follows: Figure 4 As shown: The bottom surface of the pipe forming direction is connected to the bottom structure to form a plate. The outer diameter of the pipe is 12mm, and the thickness of the connecting plate is 4mm. The design input is set as the warping force of the pipe on the plate, the connection surface with the bottom surface inside the cavity is a fixed constraint, the non-computational domain is the 3mm perimeter of the connecting plate, the calculation threshold is the other central areas of the connecting plate, and the material reduction is calculated to be (50~70)%, resulting in the topology optimization calculation threshold shape. According to the requirement of ≥45° self-forming angle, the calculation domain shape is designed on the topology optimization shape to obtain the topology-optimized connecting plate. It is then merged with the original model to obtain the optimized integrated 2-4 pipe structure, which has a material reduction of 65% compared to the original.

[0059] Step 3: Design the central 1-5 hollow ring reinforcements with a self-forming angle of 45° to obtain the self-forming 2-5 hollow ring reinforcements. For example... Figure 5 As shown, in this embodiment, a self-forming beveled structure is designed below the middle ring rib, and a 1 / 4 circular cross-section with a radius of 4mm is added to the four corners. The cross-sectional area of ​​each hole is approximately 12.56mm². 2 There is sufficient powder leakage throughput.

[0060] Step 4: Design self-forming ribs below the 1-6 top surface structure inside the cavity, which cannot yet self-form. The distance between the self-forming ribs and the solid structure in contact with the supported surface is 6mm, i.e., the rib spacing is 6mm, and the distance from the edge of the structure is 4mm. Figure 6 As shown. Weight reduction is achieved through topology optimization of the ribs, specifically as follows: Figure 7 As shown, a triangular rib shape is adopted, with a 2mm range around the edge of the structure designated as the reserved area, and the remaining central structure as the design domain. The triangular rib's surface is set to bear the structural warping stress, the planes contacting the inner wall of the cavity are fixed constraints, the topology algorithm is set to maximum rigidity, and the material reduction is 65%, resulting in a top surface structure that achieves maximum weight reduction and can self-form in 2-6 steps.

[0061] Step 5: As Figure 8 As shown, four quarter-circular process holes with a radius of 4 mm are designed at the lowest point in each cavity forming direction, and the cross-sectional area of ​​each hole is approximately 12.56 mm². 2 The cavity at the lowest point in the forming direction is designed with a process hole that connects to the outside. The hole is circular with a radius of 3mm and a cross-sectional area of ​​approximately 28.26mm². Each cavity has a process hole structure that connects to the outside near the top surface in the forming direction. This is used for cleaning and detecting foreign matter. An endoscope can be inserted through this process hole to detect foreign matter inside.

[0062] Step Six: Add necessary supports to the external suspended surface of the structural component according to the selected forming direction. The added supports should avoid the process hole structure that connects with the outside. This completes the additive manufacturing process model design.

[0063] Step 7: Select laser selective melting forming process and perform additive manufacturing according to the designed process model to complete the additive manufacturing forming.

[0064] Step 8: After completing the additive manufacturing process, utilize the process hole structure designed in Step 5 to thoroughly clean any remaining powder or excess material inside using high-pressure gas cleaning and high-pressure liquid rinsing. Continue until X-ray and endoscopic examinations show no excess material remaining.

[0065] Step 9: Continue with subsequent drying, heat treatment, support removal, grinding, and machining processes to achieve additive manufacturing of the lightweight integrated multi-cavity structure of the embodiment.

[0066] This invention proposes an additive manufacturing method for lightweight, integrated multi-cavity structural components. First, a forming direction is selected. In the process model design, a self-forming structure is designed for the partitioned structure between cavities to achieve integrated forming of the multi-cavity components. Further considering the requirements of product integration and lightweighting, integrated piping based on topology optimization, self-forming ribs, and ribs or variable-density lattice structures are designed to support internal suspended or non-self-forming surfaces. To address the issues of waste removal and inspection, interconnected process holes are designed at the lowest point of each cavity in the forming direction, connecting to the outside environment, thus completing the additive manufacturing process model design for the lightweight integrated multi-cavity structure. After additive manufacturing is completed according to the selected forming direction, residual powder, liquid, and other waste are thoroughly removed using the designed process holes, ultimately achieving the additive manufacturing of the lightweight integrated multi-cavity structure.

[0067] 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.

[0068] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for additive manufacturing of a lightweight, integrated multi-cavity structural component, characterized in that, Includes the following steps: Step 1: Design the partitioned structure between cavities that are suspended or have insufficient forming angle in the forming direction into a self-forming structure, while maintaining its function of dividing the cavity area, so as to realize the direct forming of multiple cavities in one piece; Step 2: Design an integrated pipeline based on topology optimization, connecting it to the surrounding structure using the least amount of material; the topology optimization method is as follows: connect the bottom surface of the pipeline in the forming direction to the surrounding structure to form a connecting plate, set the design input as the structural warping stress on the plate, the connection surface with the surrounding structure as the fixed surface, the non-calculation threshold as the perimeter area of ​​the plate, the calculation threshold as the center area of ​​the plate, the topology algorithm as the maximum rigidity, the material reduction amount as (50~70)%, and the perimeter area of ​​the plate as the boundary of the plate offset inward by (1~5) mm; Step 3: Design the self-forming ribs according to the self-forming angle in Step 1; Step 4: Design a support structure below the structure that cannot be self-formed inside the cavity. The support structure is a self-forming rib or a variable density lattice, and the support structure is retained after the structural component is manufactured. Step 5: Design at least one interconnected process hole structure at the lowest point of each cavity forming direction to connect the multi-cavity structures; design at least one process hole communicating with the outside at the lowest point of the interconnected multi-cavity structures in the forming direction for the discharge of internal waste; design at least one process hole structure communicating with the outside at the top surface of each cavity communicating with the outside in the forming direction for the cleaning and inspection of waste. Step 6: Add necessary supports to the outside of the structural component according to the selected forming direction. The added supports should not block the designed process hole structure that connects with the outside world. Complete the additive manufacturing process model design. Step 7: Complete the additive manufacturing process according to the additive manufacturing process selected in Step 1; Step 8: After completing the additive manufacturing process, use the process hole structure designed in Step 5 to thoroughly clean the remaining foreign matter inside. Step 9: Continue with subsequent drying, heat treatment, support removal, grinding, and machining processes to achieve additive manufacturing of a lightweight, integrated multi-cavity structure.

2. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, Self-forming structures include, but are not limited to: inclined plates at a certain angle to the horizontal direction and "pyramid" shaped plates.

3. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, In step two, if the outer diameter of the integrated pipeline is R, then the thickness of the connecting plate is 1 / 3R to R.

4. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, In step three, if the self-forming rib is a hollow rib, it must be ensured that each independent cavity space has at least one hole / groove structure that communicates with the outside.

5. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, In step three, the outer contour of the self-forming rib is triangular, the upper surface is in contact with the supported structure, and the distance from the edge of the structure is (1~5) mm; the side is in contact with the adjacent self-forming surface; the angle of the inclined side is designed according to the self-forming angle in step one.

6. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 5, characterized in that, The self-forming rib is based on the design of a hollow structure using topology optimization. The topology optimization method is as follows: the design input is the structural warping stress borne by the surface of the triangular rib, the non-calculation threshold is the perimeter area of ​​the triangular rib, the calculation threshold is the center area of ​​the triangular rib, the topology algorithm is the maximum rigidity, the material reduction is (50~70)%, and the perimeter area of ​​the rib is the boundary of the rib offset inward by (1~4) mm.

7. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, In step five, the shape of the process hole includes circular, semi-circular, and rectangular.

8. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, Methods for inspecting foreign objects using process hole structures include, but are not limited to, endoscopic examination and visual inspection.

9. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, In step one, the self-forming angle refers to the angle between the structure and the horizontal plane where the additive manufacturing is located.

10. The additive manufacturing method for a lightweight integrated multi-cavity structural component according to claim 1, characterized in that, In step eight, cleaning the remaining residue inside includes: high-pressure gas cleaning, high-pressure liquid flushing, and liquid rinsing; during the cleaning process, X-ray or endoscopic examination is used to check the residue in the cavity in real time until the residue is completely cleaned. The gas includes air and inert gas; the liquid includes water, anhydrous ethanol, acetone, gasoline, and special cleaning agents.

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