3D printing dual-material damping joint system and preparation method thereof

Abstract

The invention discloses a 3D printing dual-material damping joint system and a preparation method thereof. The 3D printing dual-material damping joint system comprises a closed-loop structure integrally formed by a closed-loop structure material through a 3D printing casting and stacking process; the conventional material part and the closed-loop structure are integrally formed through the same 3D printing process; the bionic-like structure, the closed-loop structure and the conventional material part are integrally formed; wherein the bionic-like structure is made of a closed-loop structure material, and the bionic-like structure has curve linkage action and complex curved surface wrapping. According to the 3D printing double-material damping joint system, the integrated forming design is adopted, synchronous forming of a closed-loop structure, a conventional material component and a bionic-like structure is directly achieved through the 3D printing casting stacking process, it is not needed to disassemble and assemble joints like a traditional scheme or an injection molding process, the production process is simplified, the assembly cost and the operation difficulty are reduced, and the production efficiency is improved. And meanwhile, the integrity and stability of the joint structure are improved.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, specifically to a 3D printed dual-material damping joint system and its preparation method. Background Technology

[0002] Against the backdrop of the rapid development of 3D printing additive manufacturing technology, damping joints and biomimetic structures, as core components of many mechanical structures and biomimetic devices, directly affect the overall performance of products through their design and manufacturing levels. Currently, the industry commonly adopts a single-material friction damping solution in the design and manufacturing of 3D printed joints. This solution is based on the unique fusion casting and stacking process of 3D printing to achieve molding, that is, to build the joint structure by fusing and stacking materials layer by layer. It has a certain application foundation in 3D printed products with conventional low strength and simple linkage scenarios.

[0003] However, due to the inherent characteristics of single-material friction damping and the fusion casting process of 3D printing, existing single-material friction damping solutions have significant technical defects: First, tolerance control is unstable. Joint structures that meet standards during the design phase often exhibit tolerance deviations after printing. Excessive deviations lead to difficulties in joint assembly, while excessive deviations cause the joint to lose its damping function, failing to meet basic usage requirements. Second, layer wear is a prominent issue. Due to the process characteristics, 3D printed parts have unavoidable layer textures on their surface. When two joint components work together, friction between these textures rapidly exacerbates wear, leading to joint failure in a short period. Third, damping performance decays quickly. Even if initial tolerance control meets standards, the initial damping value of a single-material joint is inherently limited, and due to rapid wear, damping performance continues to decline, further shortening the effective lifespan of the joint. Fourth, application scenarios are limited. The aforementioned problems prevent traditional printed joints from being applied to high-strength demand scenarios, making it difficult to achieve design expectations. At the same time, the inherent performance defects of the joints also limit the realization of complex linkage structures, restricting the functional expansion of 3D printed products.

[0004] Therefore, in the field of 3D printing additive manufacturing, there is an urgent need for a technical solution that can solve the problems of unstable tolerances, layer wear, rapid damping decay, and narrow application scenarios of existing single-material damping joints. Through the synergistic innovation of material properties and process design, the performance and lifespan of damping joints can be improved, while expanding the functional boundaries of 3D printed structures to meet the design needs of complex linkages and special-shaped products. Summary of the Invention

[0005] The purpose of this invention is to provide a 3D printed dual-material damping joint system and its preparation method, so as to solve the problems existing in the prior art mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a 3D-printed dual-material damping joint system and its fabrication method, comprising: A closed-loop structure integrally formed from closed-loop structural materials through a 3D printing, melting, casting, and lamination process; A conventional material component integrally formed with the closed-loop structure using the same 3D printing process; And a biomimetic structure integrally formed with the closed-loop structure and the conventional material components; The biomimetic structure is made of a closed-loop material and has curved linkage motion and complex curved surface wrapping. The closed-loop structure utilizes the elasticity and wear resistance of the closed-loop structure material, while the conventional material component provides rigid support. The closed-loop structure and the conventional material component work together to suppress wear caused by 3D printing layer textures and slow down the degradation of damping performance.

[0007] Preferably, the closed-loop structure material is TPU material, and the Shore hardness of the TPU material is 60A-90A.

[0008] Preferably, the material of the conventional material component is at least one of PLA, ABS, or PETG, wherein: When the material is PLA, its bending strength is ≥50MPa; When the material is ABS, its simply supported beam impact strength is ≥20kJ / m². When the material is PETG, its elongation at break is ≥100%.

[0009] Preferably, the conventional material component covers 1 / 3 to 2 / 3 of the closed-loop structure, and the conventional material component and the closed-loop structure form a composite structure of rigid support and elastic buffer.

[0010] Preferably, the biomimetic structure fits the target surface by more than 50%.

[0011] A method for fabricating a 3D-printed dual-material damping joint system as described in any one of the embodiments, characterized by comprising the following steps: S1) Construct a three-dimensional model of the damping joint system. The three-dimensional model includes a closed-loop structure model partition, a conventional material component model partition, and a biomimetic structure model partition. The connection area of ​​each model partition is adapted to the 3D printing interlayer fusion process. S2) Import the three-dimensional model into a 3D printer with dual-material printing capability and set the 3D printing parameters; S3) Start the 3D printer and simultaneously print a closed-loop structure, conventional material parts and biomimetic structure through a melting and layering process. The three are fused together during the printing process to form an integral structure, resulting in the printed blank of the damping joint system. S4) After the printed preform cools to room temperature, it can be taken out directly without auxiliary fastening or surface polishing, thus obtaining the 3D printed dual-material damping joint system.

[0012] Preferably, in step S1, the construction of the three-dimensional model needs to satisfy: The inner diameter of the closed-loop structure of TPU material is 0.1mm-0.3mm smaller than the diameter of the fitting connection section of conventional material parts, so as to compensate for the deviation of 3D printing process through the elasticity of TPU material.

[0013] Preferably, in step S2, if the conventional material is PLA, the printing temperature is set to 180℃-210℃; if the conventional material is ABS, the printing temperature is set to 220℃-250℃; and if the conventional material is PETG, the printing temperature is set to 210℃-230℃.

[0014] Preferably, in step S3, the printing sequence of the casting and lamination process is as follows: First, print the rigid support base section of the conventional material component, and then simultaneously print the TPU material closed-loop structure and the remaining sections of the conventional material component.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1) The 3D-printed dual-material damping joint system of this application adopts an integrated molding design. It directly realizes the synchronous molding of closed-loop structure, conventional material parts and biomimetic structure through 3D printing and casting stacking process. Unlike traditional solutions or injection molding processes, it does not require disassembling and assembling the joint, nor does it rely on auxiliary fastening parts such as screws, nuts, and glue. This design fundamentally solves the assembly difficulties or damping failure problems caused by unstable tolerance control in traditional solutions, simplifies the production process, reduces assembly costs and operation difficulty, and improves the integrity and stability of the joint structure. 2) This application utilizes the elasticity and wear resistance of the closed-loop structural material through a dual-material collaborative design to effectively suppress the friction and wear problem caused by the layer texture of 3D printed parts, and avoid the joint from failing in the short term due to layer texture wear. At the same time, the elastic characteristics of the closed-loop structural material complement the rigid support of conventional material parts, which significantly improves the initial damping value of the joint and slows down the decay rate of damping performance, greatly extending the effective service life of the joint and meeting the use requirements of high-intensity scenarios. 3) The one-piece molded dual-material structure of this application relies on a specific 3D printing dual-material melting and layering molding mode. Its structural design and process implementation are highly coupled and cannot be replicated by traditional manufacturing methods such as injection molding and machining. Even if an attempt is made to design a one-piece molded structure based on a conventional 3D printer, it is impossible to achieve structural assembly and functional compliance without adopting the dual-material synergy and interlayer fusion design of this invention. This characteristic gives this invention a unique technical barrier and effectively ensures the exclusivity and competitiveness of the technical solution. 4) This application extends the development of a biomimetic structure based on the dual-material damping joint. The elasticity and flexibility of the closed-loop structural material simulate the stretching characteristics of human muscles, breaking through the limitations of the traditional axial linkage structure. It can realize curved linkage action and adapt to the wrapping needs of complex curved surfaces such as human muscles and abdomen. This enables 3D printed products to cover more complex shapes and linkage scenarios, such as biomimetic robot joints and medical auxiliary equipment fitting structures, significantly expanding the functional boundaries and application scope of 3D printed products. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation method of this application. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of the invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of the invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] In the description of the invention, it should be noted that the execution order of the steps is not limited by the sequence number. The possible changes in the order of some steps, the synchronous execution of steps, and the split execution of steps are all within the scope of protection of this application.

[0021] Please see Figure 1 This invention provides a technical solution: a 3D-printed dual-material damping joint system and its fabrication method, comprising: A closed-loop structure integrally formed from closed-loop structural materials through a 3D printing, melting, casting, and lamination process; Conventional material components integrally formed with the closed-loop structure using the same 3D printing process; And biomimetic structures that are integrally formed with closed-loop structures and conventional material components; Among them, the biomimetic structure is made of closed-loop structural material, and the biomimetic structure has curved linkage action and complex curved surface wrapping. The closed-loop structure utilizes the elasticity and wear resistance of the closed-loop material, while conventional material components provide rigid support. The closed-loop structure and conventional material components work together to suppress wear caused by 3D printing layer textures and slow down the degradation of damping performance.

[0022] Specifically, the 3D-printed dual-material damping joint system of this application fundamentally solves the shortcomings of existing technologies through an integrated molding design of a closed-loop structure, conventional material components, and a biomimetic structure. On the one hand, the closed-loop structure and conventional material components are integrally molded using the same 3D printing process, eliminating the disassembly and assembly steps of traditional joints and the use of auxiliary components such as screws and glue. This completely avoids assembly difficulties or damping failures caused by tolerance deviations, significantly improving structural stability. On the other hand, the closed-loop structure utilizes a dual-material synergistic design that combines the elasticity and wear resistance of materials with the rigid support provided by conventional material components. The elasticity buffers the impact of layered friction, the wear resistance directly inhibits the wear rate, and the rigid support ensures the overall strength of the joint. The combination of these two factors significantly slows down damping attenuation, effectively solving the problem of short lifespan of single-material joints. At the same time, the integrated molding design of the biomimetic structure breaks through the limitations of traditional linkage structures, enabling curved linkage and complex surface wrapping, meeting the needs of special scenarios such as human body adaptation.

[0023] The closed-loop structure material is TPU, and the Shore hardness of TPU is 60A-90A.

[0024] Specifically, TPU material itself has excellent elasticity and wear resistance. Its Shore hardness range of 60A-90A can not only adapt to the joint movement gap through moderate elasticity to compensate for printing tolerances, but also resist the friction of the layer texture with sufficient wear resistance. See test example 1. Specifically, the surface wear of the closed-loop structure after 1000 reciprocating movements is ≤0.1mm, which is far better than the wear rate of joints made of single PLA or ABS materials.

[0025] Detection Example 1 Test object: A closed-loop structure made of TPU material (Shore hardness 70A), with dimensions of 8mm inner diameter, 12mm outer diameter, and 2mm thickness.

[0026] Testing tools: digital micrometer (accuracy 0.001mm), simple reciprocating motion test frame (can fix joints and achieve 0-90° reciprocating rotation, speed 30 times / minute).

[0027] Testing steps: 1. Measure the initial thickness at three different points on the surface (wear surface) where the closed-loop structure contacts a conventional material component using a micrometer, and take the average value as 2.000 mm; 2. Assemble the closed-loop structure with conventional PLA material components, fix it on the test frame, set the reciprocating rotation angle to 0-90°, and start the test frame to perform 1000 reciprocating movements; 3. After the activity, use a micrometer to measure the thickness at the same three points again, and take the average value as 1.923mm; 4. Calculate the wear amount: 2.000mm-1.923mm=0.077mm≤0.1mm.

[0028] Therefore, the wear of this TPU closed-loop structure is ≤0.1mm after 1000 reciprocating cycles.

[0029] The material of conventional material components is at least one of PLA, ABS, or PETG, wherein: When the material is PLA, its bending strength is ≥50MPa; When the material is ABS, its simply supported beam impact strength is ≥20kJ / m²; When the material is PETG, its elongation at break is ≥100%.

[0030] Specifically, PLA's flexural strength ≥50MPa ensures the joint remains undeformed under static load conditions; ABS's simply supported beam impact strength ≥20kJ / m² enhances the joint's fracture resistance under dynamic impact conditions; and PETG's elongation at break ≥100% is suitable for applications requiring a certain level of toughness. This differentiation of material performance parameters among applicable scenarios avoids overall joint strength failure due to insufficient material rigidity. Simultaneously, it precisely complements the elastic characteristics of the closed-loop structure, ensuring the synergistic effect of the rigid support and elastic buffer composite structure. This allows the system to flexibly select materials according to actual needs, improving the adaptability of the solution.

[0031] Conventional material components enclose 1 / 3 to 2 / 3 of the closed-loop structure, forming a composite structure with rigid support and elastic buffering.

[0032] Specifically, this approach provides stable rigid constraints to the closed-loop structure through the encapsulation of conventional materials, preventing excessive deformation that could lead to uncontrolled damping. Simultaneously, it preserves sufficient exposed areas of the closed-loop structure to provide elastic buffering and friction resistance, achieving a balance between rigid support and elastic damping. If the encapsulation ratio is too low, the conventional materials cannot provide effective support, and the joint is prone to failure due to excessive deformation of the closed-loop structure. If the ratio is too high, the elastic function of the closed-loop structure is suppressed, and it cannot perform its damping function.

[0033] Detection Example 2 Test subjects: Three groups of damping joint samples with different encapsulation ratios were prepared. All samples used TPU closed-loop structures (Shore hardness 70A) and PLA conventional material components, differing only in the encapsulation ratio. Sample A: Encapsulation ratio 1 / 4 (25% area of ​​the closed-loop structure encapsulated by conventional materials); Sample B: Encapsulation ratio 1 / 2 (50% of the closed-loop structure is encapsulated by conventional materials, within the range of 1 / 3-2 / 3); Sample C: Encapsulation ratio 3 / 4 (75% of the closed-loop structure is encapsulated by conventional materials).

[0034] Testing tools: spring scale (accuracy 0.1N), tensile testing frame (simulating joint load).

[0035] Test items and results: 1. Damping stability: Three groups of samples were subjected to 1000 reciprocating cycles, and the attenuation rate of the initial damping value and the damping value after the cycle was measured. Sample A: Initial damping value 1.3 N·m, after activity 0.8 N·m, attenuation rate 38.5% (due to insufficient enclosure, excessive deformation of the closed-loop structure caused the damping to drop rapidly). Sample B: Initial damping value 1.2 N·m, after activity 1.1 N·m, attenuation rate 8.3% (damping stable, meets design requirements); Sample C: Initial damping value 0.6 N·m, after activity 0.5 N·m, attenuation rate 16.7% (due to excessive wrapping, the elasticity of the closed-loop structure is suppressed, and the initial damping value is low).

[0036] 2. Structural strength: A radial pressure of 5N (simulating load) was applied to the three groups of samples, and deformation was observed. Sample A: Significant bending deformation was observed (insufficient wrapping, inadequate rigid support). Sample B: No deformation (balance between rigid support and elastic buffer). Sample C: No deformation (sufficient rigidity support, but limited damping function).

[0037] Conclusion: Only samples with a wrapping ratio in the range of 1 / 3-2 / 3 (sample B) can simultaneously meet the requirements for damping stability and structural strength.

[0038] The biomimetic structure has a fit of >50% with the target curved surface. Specifically, the fit of >50% ensures that the structure can effectively wrap the target curved surface, such as the torso surface of a biomimetic robot or the human contact surface of medical equipment, avoiding functional failures caused by insufficient fit, such as unstable wrapping or uneven pressure distribution.

[0039] A method for fabricating a 3D-printed dual-material damping joint system, characterized by comprising the following steps: S1) Construct a three-dimensional model of the damping joint system. The three-dimensional model includes a closed-loop structure model partition, a conventional material component model partition, and a biomimetic structure model partition. The connection areas of each model partition are adapted to the 3D printing interlayer fusion process. S2) Import the 3D model into a 3D printer with dual-material printing capability and set the 3D printing parameters; S3) Start the 3D printer and simultaneously print a closed-loop structure, conventional material parts and biomimetic structure through a melting and layering process. The three are fused together during the printing process to form an integral structure, resulting in the printed blank of the damping joint system. S4) After the printed preform cools to room temperature, it can be taken out directly without auxiliary fastening or surface polishing, thus obtaining the 3D printed dual-material damping joint system.

[0040] Specifically, the model partitioning and interlayer fusion in step S1 ensures that the closed-loop structure, conventional material components and biomimetic structures are tightly combined during the printing process, avoiding delamination; this method ensures that the entire process from design to manufacturing is controllable, guaranteeing the performance consistency of the final product.

[0041] In step S1, the construction of the 3D model must meet the following requirements: The inner diameter of the closed-loop structure of TPU material is 0.1mm-0.3mm smaller than the diameter of the fitting connection section of conventional material parts, so as to compensate for the deviation of 3D printing process through the elasticity of TPU material.

[0042] Specifically, the inner diameter of the closed-loop structure is smaller than the diameter of the fitting section of conventional material parts, a precise compensation design for 3D printing tolerances. Specifically, 3D printing involves process deviations. This dimensional difference utilizes the elasticity of the closed-loop structure material, such as TPU, to allow the closed-loop structure to naturally conform to conventional material parts after printing. This eliminates damping failure caused by excessive gaps and avoids joint jamming caused by excessive interference. As shown in Comparative Example 1, a range of 0.1mm-0.3mm has been practically verified to effectively compensate for printing tolerances within ±0.1mm, ensuring that the initial damping value after joint assembly remains stable within the design range of 0.5N·m-2.0N·m, thus improving the system's tolerance to process fluctuations.

[0043] Comparative Example 1 Test subjects: Four groups of damping joint samples with different dimensional differences (the difference between the inner diameter of the closed-loop structure and the diameter of the connecting section of the conventional material component) were prepared. All samples used TPU closed-loop structure (Shore hardness 70A) and PLA conventional material components, and each group of samples had a printing tolerance of ±0.1mm (simulating actual process fluctuations). Comparative Example 1-1: Dimensional difference 0mm (no compensation); Comparative Examples 1-2: Dimensional difference 0.05mm (less than 0.1mm); Comparative Examples 1-3: Dimensional difference 0.2mm (within the range of 0.1mm-0.3mm); Comparative Examples 1-4: Dimensional difference 0.4mm (greater than 0.3mm).

[0044] Testing tool: Torque wrench (accuracy 0.1 N·m).

[0045] Test item: Measure the initial damping value of each group of samples under the influence of printing tolerance (target range 0.5 N·m-2.0 N·m).

[0046] Test results: Comparative Example 1-1: Due to a dimensional difference of 0mm, after adding a tolerance of +0.1mm, the gap between the closed-loop structure and conventional material components reaches 0.1mm, and the initial damping value is 0.3N·m (below the target range, insufficient damping). Comparative Examples 1-2: Dimensional difference 0.05mm, after adding +0.1mm tolerance, the actual gap is 0.05mm, and the initial damping value is 0.4N·m (still below the target range). Comparative Examples 1-3: Dimensional difference 0.2mm, after adding ±0.1mm tolerance, the actual interference is 0.1mm-0.3mm, and the initial damping value is 1.2N·m (within the target range, the damping is stable). Comparative Examples 1-4: Dimensional difference 0.4mm, after adding a -0.1mm tolerance, the actual interference is 0.5mm, and the initial damping value is 2.5N·m (higher than the target range, joint jamming).

[0047] Conclusion: Only samples with dimensional differences within the range of 0.1mm-0.3mm (Comparative Examples 1-3) can effectively compensate for the printing tolerance of ±0.1mm, ensuring that the initial damping value is stable within the design range.

[0048] In step S2, if the conventional material is PLA, the printing temperature is set to 180℃-210℃; if the conventional material is ABS, the printing temperature is set to 220℃-250℃; and if the conventional material is PETG, the printing temperature is set to 210℃-230℃. Specifically, 180℃-210℃ for PLA, 220℃-250℃ for ABS, and 210℃-230℃ for PETG are the optimal melting and casting temperature ranges for each material. At these temperatures, the material has moderate fluidity, which allows it to bond tightly with closed-loop structural materials (such as TPU) through interlayer fusion, avoiding delamination, while also ensuring the density of its own structure and reducing the strength reduction caused by internal porosity. This solves the problem of poor bonding caused by temperature mismatch in dual-material printing, ensuring the rigid support function of the conventional material component and the synergistic effect of the closed-loop structure.

[0049] In step S3, the printing sequence of the melting and casting lamination process is as follows: First, print the rigid support base section of the conventional material component, and then simultaneously print the TPU material closed-loop structure and the remaining sections of the conventional material component.

[0050] Specifically, printing the conventional material support section first forms a stable, rigid foundation, providing a positioning reference for the subsequent printing of the closed-loop structure and preventing structural displacement due to an unstable foundation. Simultaneously printing the closed-loop structure and the remaining conventional material section ensures direct fusion of the two in the molten casting state, improving the bonding strength of the joint surfaces and thus avoiding weak interlayer bonding caused by secondary printing. This sequential design solves the problems of inaccurate structural positioning and insufficient bonding strength in dual-material printing, ensuring the integral molding quality of the system and guaranteeing the stable synergistic effect of the closed-loop structure and conventional material components.

[0051] Example 1: Damped joint of a small robotic arm, without biomimetic structure This embodiment is used for the rotational damping joint of a small robotic arm. It adopts a 3D-printed dual-material integral molding structure and does not contain any biomimetic structures, as detailed below: 1. Structural Design The damping joint consists of a closed-loop structure and conventional material components, which are integrally formed through a 3D printing and casting lamination process.

[0052] Closed-loop structure: Made of TPU material with a Shore hardness of 70A, the whole is ring-shaped with an inner diameter of 8mm, an outer diameter of 12mm, and a thickness of 2mm; Conventional material components: Made of PLA material with a bending strength of 55MPa, the overall support arm is in the shape of an "L" shape. The connecting section adapted to the closed-loop structure has a diameter of 8.2mm (the inner diameter of the closed-loop structure is 0.2mm smaller than the diameter of the connecting section). The conventional material components cover 1 / 2 of the closed-loop structure, forming a composite structure of "rigid support-elastic buffer".

[0053] 2. Preparation process S1: Construct a 3D model, which includes partitions of closed-loop structure (TPU) and conventional material parts (PLA). The connecting areas are designed in a stepped shape to adapt to the interlayer fusion process of 3D printing. S2: Import the 3D model into the dual-material 3D printer and set the printing parameters: TPU printing temperature 200℃, PLA printing temperature 190℃, layer thickness 0.2mm, printing speed 50mm / s; S3: Perform the melting and casting lamination process in the following order: First, print the rigid base section of the PLA support arm, 15mm in length, and then simultaneously print the TPU closed-loop structure and the remaining section of the PLA support arm, 10mm in length, to ensure that the two are fused together in the melting and casting state. S4: After printing, place the printed blank in an environment with a temperature of 23℃ and a relative humidity of 50% to cool naturally for 20 minutes. The finished product can be directly removed without further processing.

[0054] 3. Performance Testing Damping performance test: Using a torque tester, the joint was fixed on the test bench, the rotation angle range was set to 0-90°, the rotation speed was 60° / min, and the initial damping value was recorded as 1.2 N·m; after 10,000 consecutive reciprocating rotations, the damping value was tested again as 1.1 N·m, and the attenuation rate was calculated to be 8.3%.

[0055] Wear performance test: Using a surface profilometer, the initial surface roughness Ra of the closed-loop structure was measured to be 0.8 μm; after 1000 reciprocating rotations, the surface roughness Ra was measured again to be 1.5 μm, and the wear amount was calculated to be 0.08 mm.

[0056] Bond strength test: Using a universal tensile testing machine, the connection surface between the closed-loop structure and the PLA component was subjected to a tensile test in the vertical direction at a tensile rate of 5 mm / min. The test results showed that the bond strength was 6.2 MPa, with no delamination.

[0057] From a process feasibility perspective, the 3D printing fusion layering process and optimized printing sequence successfully achieved interlayer fusion between the closed-loop structure and conventional material components, allowing for direct molding without post-processing and solving the tolerance issues associated with disassembly and assembly in traditional solutions. In terms of performance, the initial damping value is 1.2 N·m, the attenuation rate after 10,000 cycles is only 8.3%, the wear of the closed-loop structure after 1,000 cycles is 0.08 mm, and the bonding strength of the joint surface is 6.2 MPa, all meeting design targets. This effectively suppresses defects such as 3D printing layer wear and rapid damping attenuation. Therefore, this invention demonstrates effectiveness and stability in mechanical structure damping joint scenarios.

[0058] Example 2: Elbow joint of a humanoid toy, containing a biomimetic structure This embodiment is used for the elbow joint of a 1:6 scale humanoid model, integrating a biomimetic structure to simulate the muscle coordination of the human elbow, as detailed below: 1. Structural Design The damping joint system comprises a closed-loop structure, conventional material components, and a biomimetic structure, all of which are integrally formed using a 3D printing and casting lamination process.

[0059] Closed-loop structure: Made of TPU material with a Shore hardness of 80A, the whole is ring-shaped with an inner diameter of 6mm, an outer diameter of 10mm, and a thickness of 1.5mm; Standard material components: Made of ABS material, with a simple supported beam impact strength of 22kJ / m², and an overall "U" shaped clamp arm. The diameter of the connecting section adapted to the closed-loop structure is 6.3mm, and the inner diameter of the closed-loop structure is 0.3mm smaller than the diameter of the connecting section, covering 2 / 3 of the area of ​​the closed-loop structure. Biomimetic structure: Made of the same TPU material as the closed-loop structure, the whole is in the shape of a "fan rib", with a length of 50mm, a width of 8mm and a thickness of 1mm. It is used to simulate elbow muscles and fits the muscle curves of the model arm.

[0060] 2. Preparation process S1: Construct a 3D model, which includes partitions of a closed-loop structure (TPU), conventional material components (ABS), and a biomimetic structure (TPU). The connecting areas are designed with a serrated shape to enhance the interlayer fusion effect. S2: Import the 3D model into the dual-material 3D printer and set the printing parameters: TPU printing temperature 210℃, ABS printing temperature 230℃, layer thickness 0.15mm, printing speed 40mm / s; S3: Perform the melting and lamination process in the following order: First, print the rigid base section of the ABS clamping arm, 12mm in length, then simultaneously print the TPU closed-loop structure, the remaining section of the ABS clamping arm, 8mm in length, and the TPU biomimetic structure to ensure complete fusion between the three layers. S4: After printing, place the printed blank in an environment with a temperature of 22℃ and a relative humidity of 45% for 15 minutes to cool, and then take it out directly to obtain the finished product.

[0061] 3. Performance Testing 1) Curve linkage test: Tools: protractor, ruler, marker.

[0062] Operation: 1. Mark a reference point at the connection between the upper arm and forearm of the model (outer side of the joint) with a marker. Fix the protractor at the reference point and ensure that the center of the protractor is aligned with the center of rotation of the elbow joint. 2. Slowly bend the elbow of the model, push the forearm to the maximum bending angle by hand, and read the protractor value as 140°, which is within the design range; 3. Using the elbow joint as the center, use a ruler to measure the movement trajectory of the forearm end point (away from the joint end). The distance from both ends of the trajectory to the center of the circle is 30mm. Determine that the trajectory is an arc with a radius of 30mm. 4. Use a ruler to measure the maximum gap between adjacent parts of the upper arm and forearm during the bending process. The initial gap is 0.2mm, and the gap is 0.5mm when bent to 90°. The calculated relative displacement deviation is 0.3mm, which meets the linkage stability requirements.

[0063] 2) Surface Wrapping Test: Tools: Transparent graph paper (with 1mm×1mm grid), 500g standard weights, ruler.

[0064] Instructions: 1. Cover the muscle surface (target surface) of the model arm with transparent coordinate paper, trace the outline of the surface with a pencil, and count the total number of grids within the outline, which is 200. 2. After installing the biomimetic structure, cover the wrapped area with coordinate paper again and trace the outline of the biomimetic structure fitting the curved surface. Count the number of grids in the fitting area, which is 176. Calculate the fitting degree = (176 / 200) × 100% = 88%; 3. Place a 500g standard weight (simulating daily touch and slight impact force) steadily on the biomimetic structure of the wrapping surface. After 5 minutes, remove the weight and use a ruler to measure whether there is any dent in the wrapping surface. The result shows no obvious deformation, indicating that the pressure resistance meets the daily use needs of the model toy.

[0065] 3) Damping performance test: Tools: Spring scale (range 0-5N, accuracy 0.1N), marker, timer.

[0066] Instructions: 1. Use a marker to mark a hook point on the forearm of the model toy away from the joint, and hang the spring scale hook at that point; 2. Slowly pull the spring scale so that your elbow bends from 0° to 140°. Record the reading when the spring scale stabilizes as 1.5N (corresponding to the initial damping force, which matches the designed damping value of 0.8N·m. Since the lever arm is fixed, the pulling force can indirectly reflect the magnitude of the damping). 3. Manually bend the elbow back and forth at a frequency of 1 time per second (0-140°), and use a timer to time it. After completing 8000 times, pull the spring scale again to measure. The reading is 1.4N. Calculate the attenuation rate = (1.5-1.4) / 1.5×100%≈6.7%, which meets the damping attenuation control requirements.

[0067] In terms of manufacturing process, the three components are integrated into a single unit through dual-material 3D printing. The serrated connection area design enhances the interlayer fusion effect, resulting in a highly efficient manufacturing process that requires no auxiliary assembly. In terms of function and performance, the biomimetic structure enables the elbow to complete a 30mm radius arc linkage (relative displacement deviation of 0.3mm), achieving an 88% fit with the curved surface of the model's muscle. This precisely fulfills the biomimetic requirements of curved linkage and complex surface wrapping, while maintaining an initial damping value of 0.8 N·m and a decay rate of 6.2% after 8000 cycles, balancing the simulation and durability of the model's joint. This solution solves the problems of stiff linkage, poor fit, and easy damping failure in traditional 3D printed model joints, expanding the application boundaries of this invention in the fields of biomimetic models and small biomimetic devices. This technical solution has a certain degree of adaptability to various scenarios.

[0068] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A 3D printed dual material damping joint system, characterized in that, The application relates to a damping joint system, comprising: a closed loop structure integrally formed by a closed loop structure material through a 3D printing melt-casting layering process; a conventional material component integrally formed with the closed loop structure through the same 3D printing process; and a bionic structure integrally formed with the closed loop structure and the conventional material component; wherein the bionic structure is made of the closed loop structure material, and the bionic structure has curved linkage action and complex curved surface wrapping; the closed loop structure has elasticity and wear resistance of the closed loop structure material, the conventional material component provides rigid support, and the closed loop structure and the conventional material component cooperate to inhibit wear caused by 3D printing layer lines and slow down damping performance attenuation.

2. The 3D printed dual material damping joint system of claim 1, wherein, The closed loop structure material is TPU material, and the TPU material has a Shore hardness of 60A-90A.

3. The 3D printed dual material damping joint system of claim 1, wherein, The material of the conventional material component is at least one of PLA, ABS or PETG, wherein: when the material is PLA, the bending strength is greater than or equal to 50MPa; when the material is ABS, the simply supported beam impact strength is greater than or equal to 20kJ / m2; and when the material is PETG, the elongation at break is greater than or equal to 100%.

4. The 3D printed dual material damping joint system of claim 1, wherein, The conventional material component wraps 1 / 3-2 / 3 of the closed loop structure, and the conventional material component and the closed loop structure form a composite structure of rigid support and elastic buffering.

5. The 3D printed dual material damping joint system of claim 1, wherein, The fitting degree of the bionic structure to a target curved surface is greater than 50%.

6. A method of manufacturing a 3D printed dual material damping joint system according to any one of claims 1-5, characterized in that, The application further relates to a method for manufacturing the damping joint system, comprising the following steps: S1) constructing a three-dimensional model of a damping joint system, wherein the three-dimensional model comprises a model partition of a closed loop structure, a model partition of a conventional material component and a model partition of a bionic structure, and the connection areas of the model partitions are adapted to a 3D printing interlayer fusion process; S2) importing the three-dimensional model into a 3D printer with a double-material printing function and setting 3D printing parameters; S3) starting the 3D printer, synchronously printing the closed loop structure, the conventional material component and the bionic structure through a melt-casting layering process, so that the three are integrally formed through interlayer fusion in the printing process, and a printed embryo of the damping joint system is obtained; S4) after the printed embryo cools to room temperature, the printed embryo is directly taken out without needing auxiliary fastening or surface polishing treatment, and a 3D printed double-material damping joint system is obtained.

7. The method of claim 6, wherein the 3D printed dual material damping joint system is prepared by the steps of: In step S1, the construction of the three-dimensional model needs to meet the following requirements: the inner diameter of the TPU material closed loop structure is 0.1mm-0.3mm smaller than the diameter of the adaptive connection section of the conventional material component, so as to compensate for the 3D printing process deviation through the elasticity of the TPU material.

8. The method of claim 6, wherein the 3D printed dual material damping joint system is prepared by the steps of: In step S2, if the conventional material is PLA, the printing temperature is set to 180-210 DEG C; if the conventional material is ABS, the printing temperature is set to 220-250 DEG C; and if the conventional material is PETG, the printing temperature is set to 210-230 DEG C.

9. The method of claim 6, wherein the 3D printed dual material damping joint system is prepared by the steps of: In step S3, the printing sequence of the melt-casting layering process is as follows: first, the rigid support base section of the conventional material component is printed, and then the TPU material closed loop structure and the remaining section of the conventional material component are synchronously printed.

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