Forming method of sandwich structure part in additive manufacturing
By adding supplementary strength supports to the sandwich structure and optimizing stress distribution, the cracking problem during the sandwich structure forming process was solved, achieving stable part forming, cost reduction, and improved production efficiency.
Patent Information
- Application Number
- CN202511782632.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-30
- Publication Date
- 2026-02-27
AI Technical Summary
During the laser selective melting process, the reinforcing ribs of the sandwich structure are prone to cracking, especially when the thickness of the inner and outer skins is inconsistent, which leads to high forming difficulty and production cost, and existing technologies are unable to effectively solve this problem.
By adding supplementary strength supports to the sandwich structure, optimizing the stress distribution due to the difference in thickness between the inner and outer skins, and using laser selective melting forming technology to form the parts, combined with simulation of the support structure and slicing and layering, the stability of the parts during the forming process is ensured.
It effectively reduces the risk of cracking in sandwich structure parts, improves forming stability, reduces production costs, and increases production efficiency.
Smart Images
Figure CN121571671A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of additive manufacturing technology, and in particular relates to a method for forming sandwich structure parts in additive manufacturing. Background Technology
[0002] With the development of my country's aerospace industry, many key structures have adopted a large number of complex cavity thin-walled components. The manufacturing cycle is long when using traditional technology, and many new complex parts cannot be processed using traditional processes at all.
[0003] Selective Laser Melting (SLM) is a widely used and mature process. Based on the fundamental principles of rapid prototyping, this method employs a layer-by-layer additive manufacturing approach. According to the three-dimensional model of the part, the model is sliced into layers of a specific thickness. Then, under the control of a CNC system, a laser, controlled by a galvanometer, melts the metal powder, directly forming a part with a specific geometry. SLM technology enables moldless, rapid-response manufacturing of complex cavities, spatial lattices, and other irregular structures. It significantly reduces manufacturing steps and shortens production cycles, exhibiting a clear advantage, especially in the forming of complex metal structures. It allows for integrated design and manufacturing of materials, structure, and function, providing a rapid verification technology for fast response and precise manufacturing.
[0004] Laser selective melting (LSM) forming of sandwich reinforced structures (hereinafter referred to as sandwich structures) is an important component in many 3D printed structural parts. However, during the LSM forming process of thick sandwich structures, the reinforcing ribs are prone to cracking, requiring subsequent repair through welding or scrapping. Analysis revealed that the cracking is caused by the significant difference in thickness between the inner and outer skins of the sandwich structure, resulting in differential shrinkage stress at the reinforcing ribs, leading to cracking. Figure 2 As shown, since the inner ring skin wall thickness is significantly greater than the outer ring wall thickness, the temperature rise and fall during the printing process will cause the inner ring to shrink significantly more than the outer ring. The displacement difference and stress difference of the deformation will act on the root of the interlayer reinforcing rib, eventually causing the reinforcing rib to crack.
[0005] Furthermore, the size requirements for integrated molding of sandwich structures in additive manufacturing are getting larger and larger, and the difference in stress distribution between the inner and outer skin structures is getting greater, which makes the molding of sandwich structures increasingly difficult. Summary of the Invention
[0006] To overcome the problems existing in the prior art, this invention proposes a forming method for sandwich structure parts in additive manufacturing. This method, based on the existing laser selective melting forming support system, analyzes and simulates large sandwich structure parts, adding supplementary strength supports for shape control, effectively improving the stability of the forming process. The laser-assisted forming method for sandwich structure parts provided by this invention enables stable forming of parts, reduces the risk of cracking, and lowers production costs.
[0007] This invention is implemented as follows: a method for forming sandwich structure parts in additive manufacturing, comprising the following steps: a) Construct a three-dimensional digital model of the part, perform structural analysis on the part, and determine the structural dimensions and forming direction of the part; The part has a sandwich structure, with the outer skin thickness being less than the inner skin thickness. The outer skin thickness d1 ≥ 5 mm, and the inner skin thickness d2 ≥ 1.5d1. The difference in thickness between the inner and outer skins is significant. ≥50%; The thickness of the reinforcing rib d3 is less than or equal to 1 / 2 of the thickness of the outer skin. The reinforcing rib is connected to the inner and outer skin of the part, and its height is less than the height of the skin. The upper and lower sides are not flush with the skin, and the height difference on each side is d4. b) Add process allowances to the parts; c) Add supporting structures according to the structural characteristics of the parts; d) Simulate the parts after adding the supporting structure; e) Add supplementary strength supports on both sides of the reinforcing rib; The principle for adding supplementary strength supports is as follows: the thickness of the supplementary strength support d5 = 1 / 2d1, the supplementary strength support is connected to the inner and outer skin of the part, the bottom of the supplementary strength support in the height direction is flush with the lowest line of the inner and outer skin, the forming height h1 of the supplementary strength support is at least 5mm greater than the height difference d4, and the part has no risk of cracking after simulation. f) Obtain the printing model, slice and layer the printing model, import the slice information into the device, and print.
[0008] In the above technical solutions, preferably, the selection of the forming direction of the part is based on the basic principles of good stability, small support amount, and short forming time.
[0009] In the above technical solution, preferably, the thickness d3 of the reinforcing rib is 1mm≤d3≤0.5d1.
[0010] In the above technical solution, preferably, the height difference d4 on each side is ≥ 2 mm.
[0011] In the above technical solution, preferably, the process allowance includes machining allowance, grinding allowance, and wire EDM allowance. In the above technical solution, preferably, before slicing and layering the printed model, the repair wizard function is used to repair the part model, and then non-solid supports are added to the part.
[0012] In the above technical solution, preferably, after 3D printing is completed, the surface and internal metal powder of the formed part are cleaned, the part is separated from the substrate by wire cutting, and then the outer surface of the part is ground, polished and sandblasted.
[0013] In the above technical solution, preferably, the part is manufactured by selective laser melting.
[0014] The advantages and positive effects of this invention are: This invention provides a forming method for sandwich structure parts in additive manufacturing. This forming method can optimize the overall stress distribution of parts with different inner and outer skin thicknesses by adding a small amount of support, eliminate the risk of part cracking, improve the forming stability of parts, reduce part production costs, and increase production efficiency. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the sandwich structure part provided in an embodiment of the present invention; Figure 2 This is a structural schematic diagram of the crack-prone points of the sandwich structure parts provided in this embodiment of the invention; Figure 3 This is a top view of the sandwich structure part provided in an embodiment of the present invention; Figure 4 yes Figure 3 AA section view; Figure 5 This is a schematic diagram of the forming direction of a part provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the parts provided in the embodiments of the present invention after adding supplementary strength supports. Figure 1 ; Figure 7 This is a schematic diagram of the parts provided in the embodiments of the present invention after adding supplementary strength supports. Figure 2 ; Figure 8 This is a top view of the part provided in the embodiment of the present invention after the addition of supplementary strength support; Figure 9 yes Figure 8 AA sectional view.
[0016] In the diagram: 1. Outer skin; 2. Inner skin; 3. Reinforcing rib; 4. Supplemental strength support. Detailed Implementation
[0017] To further understand the content, features, and effects of this invention, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings: To facilitate a clear description of the technical solutions in the embodiments of the present invention, it should be noted that in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.
[0018] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.
[0019] In this invention, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.
[0020] Please see Figures 1-9 This invention provides a method for forming sandwich structure parts in additive manufacturing, comprising the following steps: a) Construct a three-dimensional digital model of the part, perform structural analysis on the part, and determine the structural dimensions and forming direction of the part; The part has a sandwich structure, with the outer skin 1 being less thick than the inner skin 2. The outer skin thickness d1 ≥ 5 mm, and the inner skin thickness d2 ≥ 1.5d1. The difference in thickness between the inner and outer skins is significant. ≥50%; The thickness of the reinforcing rib d3 is less than or equal to 1 / 2 of the thickness of the outer skin. The reinforcing rib 3 is connected to the inner and outer skin of the part, and its height is less than the height of the skin. The upper and lower sides are not flush with the skin, and the height difference on each side is d4. b) Add process allowances to the parts; c) Add supporting structures according to the structural characteristics of the parts; d) Simulate the parts after adding the supporting structure; e) Add supplementary strength supports 4 on both sides of the reinforcing rib; The principle for adding supplementary strength supports is as follows: the thickness of the supplementary strength support d5 = 1 / 2d1, the supplementary strength support is connected to the inner and outer skin of the part, the bottom of the supplementary strength support in the height direction is flush with the lowest line of the inner and outer skin, the forming height h1 of the supplementary strength support is at least 5mm greater than the height difference d4, and the part has no risk of cracking after simulation. f) Obtain the printing model, slice and layer the printing model, import the slice information into the device, and print.
[0021] As a preferred implementation method, the selection of the forming direction of the part is based on the basic principles of good stability, low support amount, and short forming time.
[0022] In a preferred embodiment, the thickness d3 of the reinforcing rib is 1mm≤d3≤0.5d1.
[0023] In a preferred embodiment, the height difference d4 on each side is ≥ 2 mm.
[0024] As a preferred embodiment, the process allowance includes machining allowance, grinding allowance, and wire EDM allowance. As a preferred implementation, before slicing and layering the printed model, the part model is repaired using the repair wizard function, and then non-solid supports are added to the part.
[0025] As a preferred implementation, after 3D printing is completed, the surface and internal metal powder of the formed part are cleaned, the part is separated from the substrate by wire cutting, and then the outer surface of the part is ground, polished and sandblasted.
[0026] As a preferred embodiment, the part is manufactured by selective laser melting.
[0027] To make the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments: A method for forming sandwich structure parts in additive manufacturing, the design steps are as follows: a) Construct a three-dimensional digital model of the part, perform structural analysis on the part, and determine the structural dimensions and forming direction of the part; like Figure 1 and Figure 3 , Figure 4As shown, the part has a sandwich structure, with the outer skin thickness being less than the inner skin thickness. The outer skin thickness d1 ≥ 5 mm, and the inner skin thickness d2 ≥ 1.5d1. The difference in thickness between the inner and outer skins is significant. ≥50%; the thickness of the reinforcing rib d3 is 1mm≤d3≤0.5d1. The reinforcing rib is connected to the inner and outer skin of the part, and its height is less than the height of the skin. The upper and lower sides are not flush with the skin, and the height difference on each side is d4≥2 mm.
[0028] Specifically, use modeling software such as UG or Pro / engineer to create a 3D model of the part. The 3D software can be selected according to actual needs. This is just an example and is not a specific limitation.
[0029] In this embodiment, the outer skin thickness d1 = 5 mm, and the inner skin thickness d2 = 1.5 d1, i.e., the thickness difference. =50%; the thickness of the reinforcing rib d3 is 1mm≤d3≤0.5d1, the reinforcing rib and the skin are not of equal height, and the height difference on each side is d4=5mm. d4 can also be 4mm, and is not limited to the listed values. Other unlisted values within the range are also applicable.
[0030] Modification of the internal structure design of the part is prohibited. The forming direction of the part should be determined based on its structural characteristics, selecting the optimal placement and forming angle. The selection of the forming direction should prioritize good stability, minimal support, and short forming time. In this case, the forming direction of the part is from bottom to top. Figure 5 As shown.
[0031] b) Add process allowances to the parts, including machining allowances, grinding allowances, and wire EDM allowances.
[0032] c) Add supporting structures according to the structural characteristics of the parts.
[0033] The basic principles for adding support structures are to ensure stability, ease of dismantling, and cost-effectiveness in terms of materials and time.
[0034] d) Simulate the parts after adding the supporting structure, and analyze the stress to determine whether there is a risk of cracking.
[0035] e) Add supplementary strength supports on both sides of the reinforcing rib, such as... Figures 6-9 As shown.
[0036] like Figure 8 and Figure 9 As shown, the principle for adding supplementary strength supports is: (1) The thickness of the supplementary strength support is d5=1 / 2d1. The supplementary strength support is connected to the inner and outer skin of the part. The bottom of the supplementary strength support in the height direction is flush with the lowest line of the inner and outer skin. (2) The forming height h1 of the supplementary strength support is at least 5 mm greater than the height difference d4, so as to improve the control effect of the supplementary strength support on the part structure.
[0037] (3) The parts have no risk of cracking after simulation.
[0038] f) Open the optimized STL format part with Magics software and use the repair wizard to repair the part model.
[0039] g) Add non-solid supports to the parts.
[0040] h) Based on the forming direction of the part, slice the part into several printing layers, import the slicing information into the equipment, set appropriate printing parameters, and print.
[0041] i) Clean the surface and interior metal powder of the printed parts.
[0042] j) Perform heat treatment on the substrate of the part.
[0043] k) Use wire cutting to separate the parts from the substrate.
[0044] l) Perform overall grinding, polishing, and sandblasting on the outer surface of the parts.
[0045] In summary, this invention can optimize the overall stress distribution of parts with different inner and outer skin thicknesses by adding a small amount of support, eliminate the risk of part cracking, improve part forming stability, reduce part production costs, and increase production efficiency.
[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.
Claims
1. A method of forming a sandwich structure part in additive manufacturing, characterized in that, The method comprises the following steps: a) constructing a three-dimensional model of the part, performing structural analysis on the part, determining the structural size of the part and the forming direction of the part; The part is a sandwich structure, the outer skin thickness is less than the inner skin thickness, the outer skin thickness d1 is greater than or equal to 5 mm, the inner skin thickness d2 is greater than or equal to 1.5 d1, the difference between the inner and outer skin thicknesses is greater than or equal to 50%; the thickness d3 of the reinforcing rib is less than or equal to 1 / 2 of the outer skin thickness, the reinforcing rib is connected with the inner and outer skins of the part, the height of the reinforcing rib is less than the height of the skin, the upper and lower sides of the reinforcing rib are not flush with the skin, and the height difference of each side is d4; b) adding a process allowance to the part; c) adding a support structure according to the structural characteristics of the part; d) simulating the part after the support structure is added; e) adding a supplementary strength support on both sides of the reinforcing rib; The adding principle of the supplementary strength support is that the thickness d5 of the supplementary strength support is 1 / 2d1, the supplementary strength support is connected with the inner and outer skins of the part, the bottom of the supplementary strength support in the height direction is flush with the lowest line of the inner and outer skins, the forming height h1 of the supplementary strength support is at least 5mm larger than the height difference d4, and the part has no cracking risk after simulation; f) obtaining a printing model, slicing the printing model, inputting the slicing information into equipment, and printing.
2. The method of claim 1, wherein, The selection of the forming direction of the part is based on the basic principles of good stability, less support, and short forming time.
3. The method of claim 1, wherein, The thickness d3 of the reinforcing rib is 1mm≤d3≤0.5d1.
4. The method of claim 1, wherein, The height difference d4 on each side is ≥2mm.
5. The method of claim 1, wherein, The process allowance includes machining allowance, polishing allowance, and wire cutting allowance.
6. The method of claim 1, wherein, Before slicing and layering the printing model, the part model is repaired using the repair wizard function, and then non-solid supports are added to the part.
7. The method of claim 1, wherein, After 3D printing is completed, the surface and internal metal powder of the formed part are cleaned, the part is separated from the substrate by wire cutting, and the overall surface of the part is polished, polished, and sandblasted.
8. The method of claim 1, wherein, The part manufacturing method is laser selective melting forming.