Street lamp lighting tube with tube wall filled with crystal lattices and additive manufacturing method of street lamp lighting tube

Abstract

The invention relates to the technical field of lighting equipment, in particular to a street lamp lighting tube with lattice filling tube walls and an additive manufacturing method thereof, the street lamp lighting tube is of a double-layer tube wall sandwich structure and comprises an outer tube wall, an inner tube wall and lattice filling bodies, the outer tube wall and the inner tube wall are coaxially arranged, and an interlayer between the outer tube wall and the inner tube wall is filled with the lattice filling bodies. The outer pipe wall, the inner pipe wall and the lattice filling body are integrally formed through an additive manufacturing process. The lighting tube adopts a double-layer sandwich structure composed of the outer tube wall, the inner tube wall and the three-dimensional lattice filling body in the middle of the outer tube wall, a continuous space truss network is constructed, a height-controllable pore structure is formed, and materials can be efficiently distributed on a principal stress transmission path, so that the overall weight is remarkably reduced, and meanwhile, the service life of the lighting tube is prolonged. Due to firm metallurgical bonding at the lattice rod piece joints, the structure still keeps high specific strength and specific stiffness, and good unification of light weight and high bearing capacity is achieved.

Description

Technical Field

[0001] This invention relates to the field of lighting equipment technology, and in particular to a street light tube with a lattice-filled tube wall and its additive manufacturing method. Background Technology

[0002] Streetlights, as a crucial component of municipal infrastructure, are widely distributed across urban roads, rural highways, parks, and squares. Their safety, lightweight design, and cost-effectiveness directly impact the construction costs, operation and maintenance efficiency, and road safety of municipal projects. Currently, conventional municipal streetlight poles are typically 6-12 meters high, with tube diameters ranging from 60-140 mm, and are conical or cylindrical from top to bottom. Traditional streetlight tubes often utilize solid thin-walled metal pipes, ordinary extruded aluminum alloy pipes, or plastic composite pipes. These methods present numerous technical bottlenecks in practical applications, making it difficult to meet the high-quality development demands of modern municipal lighting.

[0003] Traditional street light tubes have poor impact resistance and energy absorption performance, making them prone to brittle fracture upon impact. Fragments of the tube wall can easily fly, causing secondary injuries. Their large weight and high material consumption not only increase material procurement costs but also raise the difficulty of hoisting, transportation, and installation, while also increasing the load on the light pole. Traditional extrusion and casting processes are difficult to achieve integrated molding of complex energy-absorbing structures, making it impossible to design gradient energy-absorbing structures suitable for different sections of the light pole, and resulting in a high molding defect rate. Current technologies have not yet applied lattice structure systems to the filling of the inner and outer wall sandwich of street light tubes, lacking synergistic optimization of lattice type, metal powder, and additive manufacturing process parameters. This makes it impossible to achieve the optimal balance between specific energy absorption, lightweighting, and molding quality, indicating a significant technological gap.

[0004] Lattice structures possess high specific strength, high specific stiffness, and excellent energy absorption properties, and have been widely used in high-end fields such as aerospace and automotive manufacturing. However, there is currently no publicly available technology for applying them to the inner and outer wall sandwich filling of street lighting tubes, adapting them to the structural parameters of conventional street light poles, and achieving a unified goal of energy absorption, impact resistance, splash prevention, lightweighting, and cost reduction, while forming a complete system of structural design, material selection, and process parameters. Therefore, developing a structurally sound, high-performance, and industrially producible lattice-filled tube wall street lighting tube and its additive manufacturing method has significant practical importance and industrial value. Summary of the Invention

[0005] To address the problems mentioned in the background section, this invention provides a lattice-filled tube for street lighting and its additive manufacturing method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a street light tube with a lattice-filled tube wall. The tube has a double-walled sandwich structure, specifically comprising an outer tube wall, an inner tube wall, and a lattice filler material filling the space between the outer and inner tube walls. The outer tube wall, inner tube wall, and lattice filler material are integrally formed using an additive manufacturing process. The outer tube wall has a thickness of 1.2-2.5 mm, the inner tube wall has a thickness of 0.8-1.8 mm, and the sandwich layer between the outer and inner tube walls has a thickness of 5-12 mm. The overall length of the light tube is 800-2200 mm, the outer diameter is 60-150 mm, and the inner diameter is 45-120 mm.

[0007] The lattice filler is a three-dimensional lattice structure, divided into multiple segments along the axial direction of the lighting tube. Each segment has a different structural density of lattice filler to achieve a structural performance gradient along the axial direction of the lamp post. The number of axial segments is 3-6, and the structural density difference between adjacent segments is 3%-8%.

[0008] The structure of the lattice filler is one or more of an octet body lattice, a body-centered cubic lattice, or a diamond lattice. When there are multiple lattice combinations, adjacent segments adopt different types of lattice structures, and the connection parts of adjacent lattice structures adopt transition lattice units with a side length of 0.5-1.2 mm.

[0009] The lattice filler is formed by additive manufacturing of metal powder, wherein the metal powder is aluminum alloy powder, stainless steel powder or titanium alloy powder; the particle size of the metal powder is 15-53μm, the sphericity of the powder is ≥90%, the loose density is 1.2-1.8g / cm³, and the flowability is ≤25s / 50g.

[0010] The lattice filler exhibits a gradient in structural density along the radial direction of the lighting tube, from the outer wall to the inner wall; and / or, along the axial direction of the lighting tube, from the bottom end to the top end of the lamp post, its structural density exhibits a decreasing gradient. Specifically, the radial density gradient rate is 2%-5% / mm; and the axial density is 22%-28% in the bottom section and 15%-20% in the top section.

[0011] The overall filling rate of the lattice filler is 15%-28%, and the overall porosity of the lighting tube is 65%-85%; the side length of the lattice unit of the lattice filler is 0.8-2.5mm, and the diameter of the lattice support rod is 0.2-0.6mm.

[0012] This invention also discloses an additive manufacturing method for producing the above-mentioned lattice-filled tube wall of a street lamp lighting tube. This method employs selective laser melting (SLM) for integral forming and specifically includes the following steps: S1. Perform slicing and layering processing based on the three-dimensional model of the lighting tube. The three-dimensional model includes the outer tube wall, the inner tube wall, and the preset lattice filling structure. The layer thickness of the slices is consistent with the thickness of the subsequent powder layer. The slice overlap rate is 10%-20%, and the modeling accuracy of the three-dimensional model is ±0.02mm.

[0013] S2. Lay a layer of metal powder in the forming chamber; the powder is spread by a scraper, the powder spreading speed is 50-120mm / s, and the powder spreading uniformity error is ≤±5μm.

[0014] S3. Based on the slice data, a laser beam is used to selectively melt the powder layer, sequentially forming the lattice filler, inner tube wall, and outer tube wall; wherein, the laser power is 180-320W, the scanning speed is 800-1400 mm / s, the powder layer thickness is 20-40μm, the laser spot diameter is 20-50μm, the scanning interval is 50-150μm, and the melting pool temperature is controlled at 1500-2200℃.

[0015] S4. Repeat steps S2 and S3, stacking layer by layer until the integrated molding of the lighting tube is completed. During the layer-by-layer stacking process, the temperature inside the molding chamber is maintained at 80-200℃ to avoid thermal stress in the molded parts.

[0016] Further, in step S3, the scanning strategy is as follows: for the support rod portion forming the lattice filler, a stripe scanning method is adopted, and the laser scanning direction between adjacent scanning layers is rotated by a specific angle; for the portion forming the outer tube wall and the inner tube wall, a boundary remelting scanning method is adopted; the specific angle is 90°, the stripe width of the stripe scanning is 0.1-0.3mm; the number of boundary remelting scans is 2-3 times, and the remelting scan spacing is 30-80μm.

[0017] Further, the metal powder is AlSi10Mg or AlSi7Mg aluminum alloy powder, the laser power is 250-280W, the scanning speed is 1000-1200 mm / s, and the powder layer thickness is 30μm; in the AlSi10Mg aluminum alloy powder, the Si content is 9.5%-10.5%, the Mg content is 0.2%-0.4%, and the remainder is Al and unavoidable impurities, with an impurity content ≤0.5%; in the AlSi7Mg aluminum alloy powder, the Si content is 6.5%-7.5%, the Mg content is 0.4%-0.6%, and the remainder is Al and unavoidable impurities, with an impurity content ≤0.5%.

[0018] Furthermore, in step S3, the protective atmosphere for the molding process is argon, and the oxygen content in the atmosphere is less than 100 ppm; the purity of the argon is ≥99.99%, the flow rate of the argon during the molding process is 5-15 L / min, and the pressure in the molding chamber is maintained at 0.1-0.15 MPa.

[0019] Furthermore, the method also includes step S5: after molding, the support structure between the lighting tube and the substrate is removed to obtain the finished product; the support structure adopts columnar support with a support diameter of 0.8-1.5mm and a support spacing of 5-10mm; the support structure is removed by mechanical grinding with a grinding accuracy of ±0.05mm, and the surface roughness Ra of the lighting tube after grinding is ≤1.6μm.

[0020] The beneficial effects of this invention are: 1. This lighting tube employs a double-layer sandwich structure consisting of an outer tube wall, an inner tube wall, and a three-dimensional lattice filler in between, constructing a continuous spatial truss network and forming a highly controllable porosity structure (overall porosity 65%-85%). This structure allows the material to be efficiently distributed along the principal stress transmission path, thereby significantly reducing the overall weight (e.g., 30%-50% weight reduction compared to traditional solid structures). Simultaneously, due to the strong metallurgical bonding at the lattice rod nodes, the structure maintains high specific strength and specific stiffness, achieving a good balance between lightweight and high load-bearing capacity.

[0021] 2. By setting multiple lattice segments with density gradients (density difference of 3%-8%) along the axial direction of the lighting tube (from bottom to top), and combining this with a possible radial density gradient, the structure can achieve orderly, progressive crushing upon impact. Microscopically, the lattice members dissipate energy through plastic bending and the formation of plastic hinges, while the gradient design induces the crushing process to progress gradually from high-density to low-density regions and from the outer layer of the structure to the interior. This mechanism helps to transform instantaneous high impact loads into a smoother response with a longer duration and lower peak value, thereby significantly reducing the maximum impact force and effectively suppressing the risk of brittle fracture or fragmentation during collision, thus improving safety performance. Transitional lattice units (side length 0.5-1.2 mm) between adjacent lattice types facilitate a smooth transition of the microscopic stress field.

[0022] 3. By using selective laser melting (SLM) to integrally form the outer and inner tube walls with the complex lattice filler, microscopic defects such as interface weakening and residual stress concentration caused by connections (e.g., welding, fastening) between different components are fundamentally avoided. Complete metallurgical bonding is achieved at the lattice nodes, resulting in a continuous and uniform microstructure, which significantly improves the static and fatigue strength of the nodes. Furthermore, the heterogeneous microstructure formed by the three-dimensional interconnected lattice and pores forces potential microcracks to frequently deflect, bifurcate, and even passivate during their propagation paths, thus consuming more energy and effectively slowing down the propagation rate of macroscopic fatigue cracks. This enhances the reliability of the lighting tube under long-term alternating loads such as wind-induced vibration.

[0023] 4. Additive manufacturing processes allow for precise digital control of microstructures, including lattice type, unit cell size (0.8-2.5mm), rod diameter (0.2-0.6mm), and gradient. By optimizing process parameters such as laser power, scanning speed, and layer thickness (e.g., laser power 180-320W, scanning speed 800-1400mm / s), and supplemented by high-purity argon protection (oxygen content <100ppm) and substrate preheating (80-200℃), it is beneficial to obtain microstructures with high density (≥99.2%) and controllable defects. Attached Figure Description

[0024] Figure 1 This invention relates to the basic tube wall structure and crystal lattice structure. Figure 2 This invention relates to the basic structure and dimensions of a street light pole. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0026] Example 1 This embodiment provides a street light tube with a lattice-filled tube wall, which has a double-walled sandwich structure. The outer tube wall, inner tube wall, and lattice filler are integrally formed by additive manufacturing. The outer tube wall thickness is 1.2 mm, the inner tube wall thickness is 0.8 mm, and the thickness of the interlayer between the outer and inner tube walls is 5 mm. The overall length of the light tube is 800 mm, the outer diameter is 60 mm, and the inner diameter is 45 mm.

[0027] The lattice filler has a three-dimensional lattice structure, divided into three segments along the axial direction of the illumination tube, with a structural density difference of 3% between adjacent segments. The lattice filler structure adopts an eight-position lattice and is formed by additive manufacturing of aluminum alloy powder (AlSi10Mg). The metal powder has a particle size of 15μm, a sphericity ≥90%, a loose density of 1.2g / cm³, and a flowability ≤25s / 50g. The content of Si is 9.5%, the content of Mg is 0.2%, and the remainder is Al and unavoidable impurities, with an impurity content ≤0.5%.

[0028] The lattice filler exhibits a gradient only along the axial direction, with structural densities of 22%, 19%, and 15% from the bottom to the top of the lighting tube, respectively. The overall lattice filler has a filling rate of 15%, and the overall porosity of the lighting tube is 85%. The lattice unit has a side length of 0.8 mm, and the lattice support rod has a diameter of 0.2 mm.

[0029] The aforementioned lighting tube is integrally formed using a selective laser melting process, the specific steps of which are as follows: S1. Based on the three-dimensional model of the lighting tube (including the outer tube wall, inner tube wall and preset lattice filling structure), slice and layer the tube. The thickness of the slice layer is consistent with the thickness of the subsequent powder layer. The slice overlap rate is 10%, and the modeling accuracy is ±0.02mm. S2. A scraper-type powder spreading method is used to spread a layer of metal powder in the forming chamber. The powder spreading speed is 50mm / s, and the powder spreading uniformity error is ≤±5μm. S3. Based on the slice data, a laser beam is used to selectively melt the powder layer, sequentially forming the lattice filler, inner tube wall, and outer tube wall. The laser power is 180W, the scanning speed is 800mm / s, the powder layer thickness is 20μm, the laser spot diameter is 20μm, the scanning interval is 50μm, and the melting pool temperature is controlled at 1500℃. The scanning strategy is as follows: the lattice filler support rod is scanned with stripes, adjacent scanning layers are rotated 90°, and the stripe width is 0.1mm; the outer tube wall and inner tube wall are scanned with boundary remelting, with two remelting cycles and a remelting scanning interval of 30μm. The protective atmosphere during the forming process is argon (purity ≥99.99%), with an oxygen content of less than 100ppm, an argon flow rate of 5L / min, and a forming chamber pressure of 0.1MPa. S4. Repeat steps S2 and S3, stacking layer by layer. During the stacking process, the temperature of the molding chamber is kept at 80°C to avoid thermal stress until the one-piece molding is completed. S5. After molding, remove the columnar support (support diameter 0.8mm, support spacing 5mm) between the lighting tube and the substrate. Remove the support by mechanical grinding with a grinding accuracy of ±0.05mm. After grinding, the surface roughness Ra of the lighting tube is ≤1.6μm, and the finished product is obtained.

[0030] Example 2 This embodiment provides a street light tube with a lattice-filled tube wall, which has a double-walled sandwich structure. The outer tube wall, inner tube wall, and lattice filler are integrally formed by additive manufacturing. The outer tube wall thickness is 1.8 mm, the inner tube wall thickness is 1.3 mm, and the thickness of the interlayer between the outer and inner tube walls is 8 mm. The overall length of the light tube is 1500 mm, the outer diameter is 100 mm, and the inner diameter is 80 mm.

[0031] The lattice filler has a three-dimensional lattice structure, divided into 4 segments along the axial direction of the illumination tube, with a structural density difference of 5% between adjacent segments. The lattice filler structure adopts a combination of body-centered cubic lattice and diamond lattice, with different lattice structures used in adjacent segments. The connecting parts use transition lattice units (side length 0.8 mm), which are formed by additive manufacturing of stainless steel powder. The metal powder has a particle size of 30 μm, sphericity ≥90%, loose density of 1.5 g / cm³, and flowability ≤25 s / 50 g.

[0032] The lattice filler exhibits a gradient change in both the radial and axial directions. In the radial direction, the structural density gradient change rate is 3% / mm from the outer tube wall to the inner tube wall. In the axial direction, the structural density is 25%, 20%, 17%, and 15% from the bottom to the top of the lighting tube, respectively. The overall filling rate of the lattice filler is 22%, and the overall porosity of the lighting tube is 75%. The side length of the lattice unit is 1.6mm, and the diameter of the lattice support rod is 0.4mm.

[0033] The aforementioned lighting tube is integrally formed using a selective laser melting process, the specific steps of which are as follows: S1. Based on the three-dimensional model of the lighting tube (including the outer tube wall, inner tube wall and preset lattice filling structure), slice and layer the tube. The thickness of the slice layer is consistent with the thickness of the subsequent powder layer. The slice overlap rate is 15%, and the modeling accuracy is ±0.02mm. S2. A scraper-type powder spreading method is used to spread a layer of metal powder in the forming chamber. The powder spreading speed is 80mm / s, and the powder spreading uniformity error is ≤±5μm. S3. Based on the slice data, a laser beam is used to selectively melt the powder layer, sequentially forming the lattice filler, inner tube wall, and outer tube wall. The laser power is 250W, the scanning speed is 1000mm / s, the powder layer thickness is 30μm, the laser spot diameter is 35μm, the scanning interval is 100μm, and the melting pool temperature is controlled at 1800℃. The scanning strategy is as follows: the lattice filler support rod is scanned with stripes, adjacent scanning layers are rotated 90°, and the stripe width is 0.2mm; the outer tube wall and inner tube wall are scanned with boundary remelting, with two remelting cycles and a remelting scanning interval of 50μm. The protective atmosphere during the forming process is argon (purity ≥99.99%), with an oxygen content of less than 100ppm, an argon flow rate of 10L / min, and a forming chamber pressure of 0.12MPa. S4. Repeat steps S2 and S3, stacking layer by layer. During the stacking process, the temperature of the molding chamber is kept at 140℃ to avoid thermal stress until the one-piece molding is completed. S5. After molding, remove the columnar support (support diameter 1.2mm, support spacing 8mm) between the lighting tube and the substrate. Remove the support by mechanical grinding with a grinding accuracy of ±0.05mm. After grinding, the surface roughness Ra of the lighting tube is ≤1.6μm, and the finished product is obtained.

[0034] Example 3 This embodiment provides a street light tube with a lattice-filled tube wall, which has a double-walled sandwich structure. The outer tube wall, inner tube wall, and lattice filler are integrally formed by additive manufacturing. The outer tube wall thickness is 2.5 mm, the inner tube wall thickness is 1.8 mm, and the thickness of the interlayer between the outer and inner tube walls is 12 mm. The overall length of the light tube is 2200 mm, the outer diameter is 150 mm, and the inner diameter is 120 mm.

[0035] The lattice filler has a three-dimensional lattice structure, divided into 6 segments along the axial direction of the illumination tube, with a structural density difference of 8% between adjacent segments. The lattice filler structure adopts a diamond lattice and is formed by additive manufacturing of titanium alloy powder. The metal powder has a particle size of 53μm, a sphericity ≥90%, a loose density of 1.8g / cm³, and a flowability ≤25s / 50g.

[0036] The lattice filler exhibits a gradient only in the radial direction, from the outer tube wall to the inner tube wall, with a structural density gradient change rate of 5% / mm; the overall lattice filler has a filling rate of 28%, and the overall porosity of the lighting tube is 65%; the lattice unit side length is 2.5mm, and the lattice support rod diameter is 0.6mm.

[0037] The aforementioned lighting tube is integrally formed using a selective laser melting process, the specific steps of which are as follows: S1. Based on the three-dimensional model of the lighting tube (including the outer tube wall, inner tube wall and preset lattice filling structure), slice and layer the tube. The thickness of the slice layer is consistent with the thickness of the subsequent powder layer. The slice overlap rate is 20%, and the modeling accuracy is ±0.02mm. S2. A scraper-type powder spreading method is used to spread a layer of metal powder in the forming chamber. The powder spreading speed is 120mm / s, and the powder spreading uniformity error is ≤±5μm. S3. Based on the slice data, a laser beam is used to selectively melt the powder layer, sequentially forming the lattice filler, inner tube wall, and outer tube wall. The laser power is 320W, the scanning speed is 1400mm / s, the powder layer thickness is 40μm, the laser spot diameter is 50μm, the scanning interval is 150μm, and the melting pool temperature is controlled at 2200℃. The scanning strategy is as follows: the lattice filler support rod is scanned with stripes, adjacent scanning layers are rotated 90°, and the stripe width is 0.3mm; the outer tube wall and inner tube wall are scanned with boundary remelting, with 3 remelting cycles and a remelting scanning interval of 80μm. The protective atmosphere during the forming process is argon (purity ≥99.99%), oxygen content is less than 100ppm, argon flow rate is 15L / min, and the forming chamber pressure is 0.15MPa. S4. Repeat steps S2 and S3, stacking layer by layer. During the stacking process, the temperature of the molding chamber is kept at 200℃ to avoid thermal stress until the one-piece molding is completed. S5. After molding, remove the columnar support (support diameter 1.5mm, support spacing 10mm) between the lighting tube and the substrate. Remove the support by mechanical grinding with a grinding accuracy of ±0.05mm. After grinding, the surface roughness Ra of the lighting tube is ≤1.6μm, and the finished product is obtained.

[0038] Comparative Example 1 Structural design: no lattice filling, solid structure, total wall thickness of 10mm (consistent with the total wall thickness of Example 1), no inner and outer wall delamination, suitable for 80-120mm pipe diameter and 3-8m height light poles, consistent with the light pole specifications of Example 1.

[0039] Material: Ordinary 6061 aluminum alloy, produced by extrusion molding process, without additive manufacturing steps.

[0040] Performance test results: molding density 98.5%, surface roughness Ra 18 μm; specific energy absorption 4.8 kJ / kg, weight is 1.72 times that of Example 1; brittle fracture occurred upon impact, tube wall fragments flew, the maximum impact force was 54% higher than that of Example 1, the main body damage was 45% higher than that of Example 1; material cost was 38% higher than that of Example 1.

[0041] Comparative Example 2 Structural design: no lattice filling, solid structure, total wall thickness of 13mm (consistent with the total wall thickness of Example 2), no inner and outer wall delamination, suitable for light poles with a diameter of 120-140mm and a height of 6-10m, consistent with the light pole specifications of Example 2.

[0042] Material: Ordinary 304 stainless steel, produced using sand casting process.

[0043] Performance test results: The molding density is 97.8%, the surface roughness Ra is 25 μm, and there are a few pore defects; the specific energy absorption is 4.2 kJ / kg, and the weight is 2.29 times that of Example 1 (2.13 times that of Example 2); severe brittle fracture upon impact, obvious fragmentation, and the maximum impact force is 67% higher than that of Example 2; good corrosion resistance, but heavy weight and high cost, with material cost being 280% of Example 1 (2.8 times that of Example 2).

[0044] Comparative Example 3 Structural design: A single diamond lattice is filled in the interlayer between the inner and outer tube walls. Both inner and outer tube walls are 2mm thick, and the total tube wall thickness is 13mm (consistent with the total wall thickness in Example 2). The unit size is 8mm, the rod diameter is 1.2mm, and the interlayer filling rate is 25%. It is suitable for light poles with a tube diameter of 120-140mm and a height of 6-10m, consistent with the light pole specifications in Example 2.

[0045] Material: TC4 titanium alloy powder, particle size 15–53 μm, density 4.5 g / cm³.

[0046] Additive manufacturing process: SLM forming, laser power 320 W, scanning speed 800 mm / s, layer thickness 30 μm, scanning spacing 0.14 mm, substrate preheating temperature 180 ℃, and other process parameters are the same as in Example 2.

[0047] Performance test results: Molding density 99.2%, surface roughness Ra 13 μm; specific energy absorption 12.8 kJ / kg, weight is 1.45 times that of Example 1 (1.35 times that of Example 2); local brittle fracture occurs upon impact, with a small amount of fragments flying; material cost is 950% of Example 1 (9.5 times that of Example 2), molding is difficult, and it is not suitable for mass production.

[0048] Comparative Example 4 Structural design: A single BCC lattice is filled in the interlayer between the inner and outer tube walls, with no gradient design. Both the inner and outer tube walls are 2mm thick, and the total tube wall thickness is 10mm (consistent with the total wall thickness in Example 1). The unit size is 8mm, the rod diameter is 1.2mm, and the interlayer filling rate is 20%. It is suitable for light poles with tube diameters of 80-120mm and heights of 3-8m, consistent with the light pole specifications in Example 1.

[0049] Material: AlSi10Mg aluminum alloy powder, consistent with Example 1.

[0050] Additive manufacturing process: completely consistent with Example 1.

[0051] Performance test results: molding density 99.5%, surface roughness Ra 10 μm; specific energy absorption 7.2 kJ / kg, weight basically the same as in Example 1; uneven plastic deformation during collision, local stress concentration, no fragments flying, but the energy absorption effect is 32% worse than in Example 1.

[0052] To clearly demonstrate the technical advantages of the present invention, the core performance parameters of the above three embodiments and four comparative examples are summarized and compared, as shown in Table 1 below: Table 1. Results of core performance parameters for Examples 1-3 and Comparative Examples 1-4 From the above table and Figure 1-2 As can be seen, all three embodiments of the present invention exhibit excellent comprehensive performance, showing significant advantages compared to comparative examples (existing technology and non-preferred solutions). Furthermore, all three strictly adhere to the sandwich structure design of "2mm inner and outer tube walls and 8-15mm total wall thickness," resulting in a reasonable structure and stable molding. The specific energy absorption of Examples 1-3 is 8.5-10.5 kJ / kg, which is 81%-150% higher than that of Comparative Example 1 (4.8 kJ / kg) and Comparative Example 2 (4.2 kJ / kg) of traditional molding technology. Although the specific energy absorption of Comparative Example 3 (12.8 kJ / kg) is slightly higher, it has the disadvantages of extremely high cost and splashing upon impact. The energy absorption performance of Example 1 is 46% higher than that of Comparative Example 4 (7.2 kJ / kg) with a single BCC lattice. This proves that the preferred eight-position bulk lattice and gradient lattice design of the present invention, combined with the sandwich structure, can significantly improve the energy absorption effect of the lighting tube and meet the impact resistance requirements of the lamp post.

[0053] The relative weight of Examples 1-2 is much lower than that of Comparative Examples 1 and 2 of the traditional molding technology, and also lower than that of Comparative Example 3. Among them, the weight of Example 1 is 42% lower than that of the traditional extruded solid tube of the same specification, which effectively reduces the load on the light pole, improves the overall stability of the light pole, and reduces the cost of hoisting, transportation and installation, thus meeting the lightweight requirements of municipal street lights. Moreover, the sandwich structure (both inner and outer walls are 2mm) ensures strength and avoids the weight redundancy of solid tubes.

[0054] All embodiments achieved layer-by-layer plastic crushing upon impact, without brittle fracture or fragmentation, thus avoiding secondary damage. In contrast, Comparative Examples 1 and 2 showed obvious brittle fracture and fragmentation upon impact, while Comparative Example 3 showed localized brittle fracture and a small amount of fragmentation. This demonstrates that the lattice structure design of the present invention, combined with the sandwich structure of "inner and outer tube walls + intermediate lattice", can significantly improve the collision safety of the lighting tube and is suitable for the outdoor use requirements of municipal streetlights.

[0055] The molding density of Examples 1-3 is ≥99.2%, and the surface roughness Ra is 8–16 μm, which is better than that of Comparative Example 1 (Ra 18 μm) and Comparative Example 2 (Ra 25 μm) of traditional molding technology. The molding quality is stable and the defect rate is low. At the same time, the material cost of Examples 1-2 is much lower than that of Comparative Example 2 (280% of Example 1) and Comparative Example 3 (950% of Example 1). Compared with Comparative Example 1 (138% of Example 1) and Comparative Example 4 (equivalent to Example 1), it has a greater cost advantage and achieves the optimal balance between performance and cost, which is suitable for mass production of municipal street lights. Moreover, the molding process of the sandwich structure is mature, and the inner and outer tube walls are integrally molded with the crystal lattice without splicing defects.

[0056] Example 1 is compatible with mainstream 80-120mm pipe diameter and 3-8m height light poles (total wall thickness 10mm, interlayer 6mm). Example 2 is compatible with 120-140mm pipe diameter and 6-10m height light poles (total wall thickness 13mm, interlayer 9mm). Example 3 is compatible with heavy-duty light poles in highly corrosive environments (total wall thickness 15mm, interlayer 11mm). The interlayer thickness varies with the pipe diameter, covering the main specifications of conventional municipal street lights and the needs of special scenarios. However, the compatibility range of Comparative Examples 1-4 is narrower and cannot meet the needs of light poles of different specifications and in different scenarios.

[0057] In summary, this invention, through a sandwich structure design of "outer tube wall + inner tube wall + intermediate lattice interlayer" (both inner and outer tube walls are 2mm thick, with a total wall thickness of 8–15mm), combined with the synergistic optimization of lattice type, gradient structure, powder materials, and additive manufacturing process parameters, solves many bottlenecks in existing technologies. It achieves the integrated goals of high specific energy absorption, impact resistance, splash prevention, lightweight, and cost reduction in lighting tubes. It is adaptable to municipal street light poles of different specifications and scenarios, and the process is mature and can be mass-produced, demonstrating significant technical advantages and industrial value.

[0058] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A street light tube with a lattice-filled tube wall, characterized in that, It is a double-walled sandwich structure, including an outer tube wall, an inner tube wall and a lattice filler filled in the interlayer between the outer tube wall and the inner tube wall, wherein the outer tube wall, the inner tube wall and the lattice filler are integrally formed by additive manufacturing process; The lattice filler is a three-dimensional lattice structure, divided into multiple segments along the axial direction of the lighting tube. The lattice filler in each segment has a different structural density to achieve a structural performance gradient along the axial direction of the lamp post.

2. The lattice- filled tube wall luminaire tube of claim 1, wherein, The structure of the lattice filler is one or more combinations of an octet body lattice, a body-centered cubic lattice, or a diamond lattice.

3. The lattice- filled tube wall luminaire tube of claim 2, wherein, The lattice filler is formed by additive manufacturing of metal powder, wherein the metal powder is aluminum alloy powder, stainless steel powder or titanium alloy powder.

4. The lattice- filled tube wall luminaire tube of claim 1, wherein, The lattice filler exhibits a gradient change in structural density along the radial direction of the lighting tube, from the outer tube wall to the inner tube wall; and / or, along the axial direction of the lighting tube, from the bottom end to the top end of the lamp post, its structural density exhibits a decreasing gradient change.

5. The lattice-filled tube wall luminaire tube of any of claims 1-4, wherein, The overall filling rate of the lattice filler is 15%-28%, and the overall porosity of the lighting tube is 65%-85%.

6. An additive manufacturing method for manufacturing a street lighting tube with a lattice-filled tube wall according to any one of claims 1-5, characterized in that, The integral molding process using selective laser melting includes the following steps: S1. Perform slicing and layering processing based on the three-dimensional model of the lighting tube, wherein the three-dimensional model includes an outer tube wall, an inner tube wall, and a preset lattice filling structure; S2. Lay a layer of metal powder inside the molding chamber; S3. Based on the slice data, a laser beam is used to selectively melt the powder layer to sequentially form the lattice filler, inner tube wall, and outer tube wall; wherein, the laser power is 180-320W, the scanning speed is 800-1400 mm / s, and the powder layer thickness is 20-40μm. S4. Repeat steps S2 and S3, stacking layer by layer until the integrated molding of the lighting tube is completed.

7. The additive manufacturing method of claim 6, wherein, In step S3, the scanning strategy is as follows: for the support rod portion forming the lattice filler, a stripe scanning method is used, and the laser scanning direction between adjacent scanning layers is rotated by a specific angle; for the portions forming the outer tube wall and inner tube wall, a boundary remelting scanning method is used.

8. The additive manufacturing method of claim 6, wherein, The metal powder is AlSi. 10 The laser used is Mg or AlSi7Mg aluminum alloy powder, with a laser power of 250-280W, a scanning speed of 1000-1200 mm / s, and a powder layer thickness of 30μm.

9. The additive manufacturing method of claim 6, wherein, In step S3, the protective atmosphere for the molding process is argon, and the oxygen content in the atmosphere is less than 100 ppm.

10. The additive manufacturing method according to claim 6, characterized in that, The method further includes step S5: after molding is completed, the support structure between the lighting tube and the substrate is removed to obtain the finished product.

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