A multi-directional detachable equal-diameter circular tube insertion node based on angle bisecting plane cutting

Abstract

A multi-directional detachable equal-diameter circular tube insertion node based on angle bisector cutting, wherein "multi-directional" refers to multiple numbers and multiple directional angles, supports the node construction at the intersection of two or more equal-diameter circular tube rods with arbitrary spatial angles other than overlap in three-dimensional space. The node includes a rod (2) and a sleeve (1) corresponding to the rod (2). The rod (2) and the corresponding sleeve (1) are connected by an insertion structure. The insertion structure refers to the end of the rod (2) being a reduced-diameter tube (3) inserted into the corresponding sleeve (1). A structural adhesive layer (4) is provided in the gap between the reduced-diameter tube and the sleeve. The sleeves (1) are connected as one unit at the intersection. This utility model has the characteristics of strong universality, easy selection, easy processing, easy transportation, easy construction, maintenance-free, internal interconnection and good airtightness. It is an ideal node for expanding the concept in the fields of temporary steel structure construction, landscape decoration, furniture support, pipeline structure and lamp decoration.

Description

Technical Field

[0001] This utility model relates to the fields of temporary steel structure buildings, landscape decoration, furniture supports, pipeline structures and lighting decoration, and in particular to a connection node of a spatial grid structure. Background Technology

[0002] Steel pipes are a commonly used material in the steel structure field, with a complete range of market specifications and easy procurement. The steel pipes referred to here are round metal pipes, excluding square and rectangular pipes. In the field of building steel structures, where material costs account for a high percentage, different outer diameters of steel pipes are more conducive to material savings. Furthermore, according to the calculation formula for direct welded joints of steel pipes in the "Steel Structure Design Standard GB50017-2017," the load-bearing capacity of branch pipes at the joint is much less than the cross-sectional load-bearing capacity of the main pipe. This limits the application of direct welded joints of steel pipes in spatial grid structures from a stress perspective, resulting in the entire industry failing to explore the application potential of equal-diameter steel pipes in spatial grid structures under low-load conditions. For areas such as temporary building steel structures, landscape decoration, furniture supports, pipeline structures, and lighting decorations, where loads are relatively small, material costs account for a small percentage, and labor costs account for a high percentage, there is a lack of a universally applicable spatial grid joint. Considering aesthetic factors, the material cannot be too thin. Under low load conditions, the stress in the members is far less than their maximum bearing capacity. Therefore, the bearing capacity requirements for the member joints are relatively low, while the requirements for the joints' universality, ease of transportation, ease of installation, and disassembly are relatively high. However, due to the lag between theoretical and practical needs, no joint can simultaneously possess all these advantages. The advantages and disadvantages of five existing spatial grid circular tube connection joint technologies are explained below:

[0003] The first type is a connection node between the main and secondary pipes. The structure lacks independent core components; the intersections of the members are welded together. It consists of one main pipe and several secondary pipes. The main pipe is continuous, and the secondary pipes are welded to the main pipe after intersecting at their joints. The advantages are that the main pipe diameter can be larger than the secondary pipe diameter, resulting in good load-bearing capacity. The disadvantages are the difficulty in positioning the main and secondary pipes, low installation accuracy, and the difficulty in machining the intersecting joints. (See attached image) Figure 15 As shown.

[0004] The second type is the welded spherical joint, which has an independent core component, typically a hollow steel sphere, welded to the members. Its advantages include an independent core component, ease of machining, straight members for easy material cutting, and good load-bearing capacity. The disadvantage is that it is only suitable for members with large angles; when the angles are small, the diameter of the welded sphere increases drastically, affecting aesthetics and load-bearing capacity. (See attached image) Figure 16 As shown.

[0005] The third type involves cast steel and 3D-printed nodes, with an independent node core in the structure, all integrally molded. Its advantages include versatility, independent node core components for easy transportation, straight-edged members for easy cutting, and good load-bearing capacity. The disadvantages are the heavier node core components, higher processing costs, and greater design complexity. (See attached image.) Figure 17 As shown.

[0006] The fourth type is a specific angle sleeve node, mostly used in furniture supports, pipeline transportation, etc., supporting several specific connection angles of 45, 60, and 90 degrees and specific numbers of links. Its advantages are low mass production cost, easy transportation, and easy installation; its disadvantages are limited application range for fixed angles and fixed links. (See attached image) Figure 18 As shown.

[0007] The fifth type is the steel pipe bevel splicing node, which refers to a node where two steel pipes of equal diameter are spliced ​​together at an bevel and then welded together. The advantage is simple processing; the disadvantage is a limited number of members and the lack of independent core components, making on-site splicing difficult. (See attached image.) Figure 19 As shown.

[0008] Based on the above five existing technologies, it can be seen that: the main and secondary pipe intersection connection nodes, welded ball nodes, cast steel and 3D printed nodes all have the problem of being difficult to install and position; the specific angle sleeve nodes and steel pipe bevel splicing nodes have limited applicability; and for equal diameter circular pipes, there is still no universal connection node that is not limited by the number of members, the angle of the members, and is easy to install. The emergence here refers not only to the emergence of physical objects, but also to the emergence of related mathematical theories. Utility Model Content

[0009] This utility model aims to fill a gap in the industry by proposing a multi-directional detachable equal-diameter circular tube insertion node based on angle bisector cutting. The node is a key component connecting intersecting members. Its key feature is that the node includes two or more members and corresponding sleeves. "Corresponding" means that their centerlines are collinear and have the same outer diameter. The members and corresponding sleeves are connected by an insertion structure. This insertion structure refers to the member's end being a reduced-diameter tube inserted into the corresponding sleeve. A structural adhesive layer is provided in the gap between the reduced-diameter tube and the sleeve. The sleeves are connected as a single unit at the intersection. "Intersection" refers to the intersection of the sleeve centerlines at point O; the area containing this point is the intersection point. The confluence is a polyhedral cone. The polyhedral cone is formed when the confluence of the sleeves is considered solid and extends infinitely, and it is cut along the corresponding angle bisector of the other sleeves in the node. Point (O) is the vertex. When the polyhedral cone is composed of two planes, point (O) is the midpoint of the intersection line. The angle bisector is the plane containing the angle bisector of the center lines of the two sleeves and the normal line of the plane determined by the center lines of the two sleeves. There is a weld on the outer surface contour line of the polyhedral cone. The weld connects the sleeves in the node into a whole, which is the core component of this node. The sleeves connected by the weld are closed. The closure means that there are no misalignments, openings or collisions in the pipe wall, and both the inner and outer surfaces are closed. The rod is a rigid round tube with the same outer diameter and a certain degree of plasticity. The end of the tube is flush with the diameter reduction. The end of the tube with the reduced diameter is also flush with the diameter. The flush with the diameter is a plane perpendicular to the center line of the rod. The sleeve is a metal round tube with uniform wall thickness. The tensile and compressive strength of the sleeve section is not less than the maximum tensile and compressive strength of the rod section in the node. The side of the sleeve closest to the corresponding rod is flush with the diameter. The length of the uncut part of the sleeve should not be less than the insertion length of the tube with the reduced diameter of the rod.

[0010] Furthermore, the aforementioned polyhedral cone refers to a cone formed when the confluence of sleeves is considered solid and extends infinitely, and it is cut along the corresponding angle bisector of other sleeves in the node. Point (O) is the vertex, and when the polyhedral cone consists of two planes, point (O) is the midpoint of the intersection line. Because the intersection of two intersecting lines that determine the angle bisector is point (O), point (O) lies on all angle bisectors cutting the polyhedral cone, and further on the intersection line of any two angle bisectors. Since member 1 does not coincide, any two angle bisectors are not parallel, and the intersection line must exist. The intersection line is also an edge of the polyhedral cone. Because all intersection lines intersect at point (O), point (O) is the vertex of the polyhedral cone. The cutting refers to cutting sleeve 1 through a plane so that all or part of sleeve 1 is located on one side of the cutting surface, retaining member 2, without limiting the cutting depth or order. The cutting depth refers to the cutting surface being considered an infinitely extending plane, where the sleeves 1 cut by it will not stick together, and there will be no situation where only one cut is not completed, allowing all sleeves 1 to be located on one side of the cutting surface. The order refers to the fact that each sleeve 1 can be cut in any order with all other sleeves 1 in the core component, and the final cut head remains unchanged. This differs from the concave cutting surface of the cut head in the primary and secondary pipe intersection connection node of the prior art 1, where the secondary pipe is considered a solid.

[0011] Furthermore, the splice weld of the sleeve is a semi-penetration weld. When the joint strength requirement is high, a fillet weld can be added to the outside to improve the welding strength. The splice seam can be seen from the inside. It has a different structure from the castings in prior art 3 and 4.

[0012] Furthermore, the length of the reduced-diameter tube at the end of the rod should not be less than the corresponding sleeve diameter, and the end of the reduced-diameter tube can be tapered for easy connection. The load-bearing capacity of the plug-in structure can be calculated according to the standard formula F=μ*σ*A, where σ is the structural adhesive strength, A is the corresponding contact area, and μ is the reduction factor (μ≤0.8). For example, for a sleeve with an inner diameter of φ25 and an insertion depth of 25mm, using epoxy resin AB glue with a shear strength (steel-to-steel) σ≥12Mpa and μ=0.8, its load-bearing capacity F=17.34KN; when the rod section is φ25*0.75 and the material is Q304 stainless steel, its cross-sectional tensile and compressive load-bearing capacity =17.37 KN≈F. It can be seen that using structural adhesive layer connection can achieve equal strength connection for some thin-walled steel pipes. Even if equal strength connection is not achieved, the load-bearing capacity provided is sufficient to meet the actual project requirements. The plug-in structure can also improve the sleeve stiffness to a certain extent without affecting the internal connection, providing additional benefits. The end-diameter reduction tube of the rod is processed in one step using a hydraulic compression fitting machine, resulting in a beautiful and durable product.

[0013] Furthermore, the structural adhesive layer must meet certain structural requirements. The structural adhesive is a slow-curing type. When the structure needs to be disassembled, epoxy AB adhesive or anaerobic threadlocker is selected, which has easy disassembly characteristics. When disassembly is required, a hot air gun is used to heat the insertion structure, causing the internal structural adhesive layer to soften and fail, thus facilitating disassembly without damaging the structural paint film or causing surface oxidation and discoloration. The gap between the reduced-diameter tube of the member and the corresponding sleeve must meet both the installation requirements (≥0.1mm) and the stress requirements of the structural adhesive layer, generally ≤1mm.

[0014] Furthermore, both ends of the aforementioned rod are intersections of different rods, and can both serve as nodes. In three-dimensional space, the end of a rod contains six degrees of freedom: movement along the x, y, and z axes, and rotation around the x, y, and z axes. In its local coordinate system, the direction of the rod's centerline is considered the x-axis. The plug-in structure in the node can be considered a rigid connection within the load-bearing capacity range, completely restricting these six degrees of freedom of the rod. Rotation around the x-axis is independently restricted by the structural adhesive layer. The misalignment at the transition point from the rod end to the reduced-diameter tube provides positioning along the x-axis. Because the structural adhesive layer has slow-curing characteristics, the node does not restrict the rod's rotation around the x-axis during installation, which greatly reduces installation difficulty—a unique advantage of the plug-in structure. For example, existing threads cannot provide positioning along the x-axis, and existing bolts restrict the rod's rotation around the x-axis during installation, or although they do not restrict rotation around the x-axis, they cannot constrain rotation around the y and z axes. The plug-in structure should be considered an important component of this node.

[0015] Furthermore, the term "multi-directional" refers to a large number of directions and angles, supporting the construction of nodes at the intersection of two or more equal-diameter rods in three-dimensional space, excluding overlap, at any spatial angle. Nodes are supported and installable for any rod without a reduced-diameter tube length L≥0. When a rod is too short and the rod and sleeve are made of the same material, one side of the rod can be merged with the sleeve, omitting the reduced-diameter tube and structural adhesive layer on that side. In this case, the rod wall thickness equals the wall thickness of the sleeve it merges with. When the rod length L (excluding the reduced-diameter tube) is ≥ the result of the theoretical calculation formula a below, it can be installed without using the overall scaling mode. (See attached...) Figure 10 Explanation: Let the insertion depth be L1, the insertion gap be d (one side fits tightly against the other side), the length of the rod excluding the constriction be L, and the angle between the moving direction of the core component at the mounting end and the direction of the rod be θ, then:

[0016] sinα=d / L1

[0017] ψ=θ-α

[0018] L = L1 * sinψ / (sinθ - sinψ)

[0019] The overall scaling mode described is a general principle for node installation, applicable to any spatial mesh structure using this node. The proof is as follows: The 3D model of the spatial mesh structure is enlarged as a whole. The core component moves with the node, and the rods move with their center points. During the enlargement process, the component dimensions and orientation remain unchanged, causing the rods to completely detach from the core component. This can be considered the state before installation. Then, the entire mesh is scaled down, returning to the initial state. This can be considered the installation process. During the scaling down, all rods sequentially contact their corresponding sleeves according to their inter-joint lengths from shortest to longest, and are successively inserted and tightened to complete the simulated installation. This proves that this multi-directional detachable equal-diameter circular tube insertion node can be installed for any spatial mesh structure. In actual installation, for ease of installation, there is a gap of approximately 50 micrometers between the outer diameter of the reduced-diameter tube portion of the rod in the insertion structure and the inner diameter of the corresponding sleeve. During installation, the shorter rods are installed first, followed by the longer rods, and all are tightened together. Installation is successful in all cases.

[0020] A specific application example of the theoretical calculation formula is as follows: When L1=25mm, d=0.5mm, and θ=30°, L=692.5mm is obtained. According to the formula, L is positively correlated with L1 and θ, negatively correlated with d, and independent of the diameter and wall thickness of the circular tube. When θ≤α, L≤0, which is considered to have no impact on installation. This formula is applicable to the situation where the core component on one side (side a) of member 2 is fixed, and the core component on the other side is movable. In actual installation, when the structural adhesive layer 4 at the node insertion point has not exceeded its initial curing time (0.15~2 hours), the core component on side a can also rotate slightly, and the actual L will be smaller than the theoretical value. From the specific application example, it can be seen that the minimum length L that does not affect installation is relatively easy to meet. The theoretical derivation of this overall scaling mode and the minimum L calculation formula are of great significance for the installation of this node and similar insertion nodes. It belongs to the invention point of this node and should be regarded as an innovation.

[0021] Furthermore, the hollow and interconnected nature of the core components, the hollow nature of the rods, and the airtightness of the sleeve splicing welds and plug-in structures give the structure formed by these nodes the characteristics of being internally interconnected and closed.

[0022] The beneficial effects of this utility model are:

[0023] This utility model node is characterized by its strong applicability, ease of selection, ease of processing, ease of transportation, ease of construction, maintenance-free operation, internal interconnection, and good airtightness. It is an ideal node for expanding the design concepts in the fields of temporary steel structure buildings, landscape decoration, furniture supports, pipeline structures, and lighting decoration. Attached Figure Description

[0024] Figure 1This is a perspective structural diagram of one embodiment of the multi-directional detachable equal-diameter circular tube insertion node described in this utility model;

[0025] Figure 2 yes Figure 1 The top view serving as the main view;

[0026] Figure 3 yes Figure 1 The right view as the main view

[0027] Figure 4 yes Figure 1 The rear view as the main view

[0028] Figure 5 yes Figure 1 Outer contour drawing in view direction

[0029] Figure 6 yes Figure 1 A cross-sectional view of the separating member and its front views in relation to the planes formed by the other five members.

[0030] Figure 7 yes Figure 1 Innovative cutting diagram of the sleeve corresponding to the middle separation rod.

[0031] Figure 8 yes Figure 1 Drawing process diagrams and theoretical proof illustrations for innovative blanking diagrams of sleeves corresponding to the middle separation rods;

[0032] Figure 9 It is an illustration to prove the conclusion that the walls of any two sleeves coincide on the cut surfaces;

[0033] Figure 10 It is an illustration accompanying the theoretical calculation formula for the minimum length of a member that does not affect installation;

[0034] Figure 11 This is a schematic diagram of the membrane structure tent described in Example 1;

[0035] Figure 12 This is a structural schematic diagram of the polyhedral outline bear sculpture described in Example 2;

[0036] Figure 13 This is a schematic diagram of the round-and-square table structure described in Embodiment 3;

[0037] Figure 14 This is a schematic diagram of the spatiotemporal channel project structure described in Example 4;

[0038] Figure 15 This is a schematic diagram of the structure of the connection node of the main and secondary pipe intersection line in the prior art form 1 described in the background art of this utility model;

[0039] Figure 16 This is a schematic diagram of the structure of the prior art form 2 welded ball joint described in the background art of this utility model;

[0040] Figure 17 This is a structural schematic diagram of the prior art form 3 cast steel and 3D printed node described in the background art of this utility model;

[0041] Figure 18 This is a schematic diagram of the structure of the prior art form 4, a sleeve node with a specific angle, as described in the background art of this utility model.

[0042] Figure 19 This is a structural schematic diagram of the prior art form 5 steel pipe bevel splicing node described in the background art of this utility model;

[0043] Figure label:

[0044] 1—Casing;

[0045] 2—Staff member;

[0046] 3—Reduced diameter pipe;

[0047] 4—Structural adhesive layer;

[0048] a——The cutting surface at the sleeve splicing position is a schematic diagram of the angle bisector;

[0049] b—Schematic diagram of sleeve connection between rod and core component;

[0050] c - Schematic diagram of the arc transition at the diameter reduction section of the rod;

[0051] d—Schematic diagram of the end of the reduced-diameter tube of the rod for easy installation and closing;

[0052] e – This is a schematic diagram showing the flush joint between the rod and the sleeve.

[0053] O—Intersection of the centerlines of the members; Detailed Implementation

[0054] The problem of intersecting multi-directional members in space has always been a challenge in the industry. In practical applications, the configuration design is often based on the applicable scope of nodes listed in 1-5 of the existing technology. This greatly limits the diversity of spatial grid structure configurations. A good type of multi-directional member intersection node should not limit the number of members or spatial angles, should have the principle of universality, should be supported by mathematical theory, should ensure the consistency of nodes, and should not lead to different styles of detailed nodes due to different understandings of technical personnel in the relevant field. It should also have certain efficiency and cost advantages. This node type has these advantages. The reason why similar nodes have not appeared in the industry is that plug-in structures have both advantages and disadvantages. The disadvantage is that the existing technology has not solved the installation problem of plug-in structures for multi-directional members in space. The industry's inherent impression is that plug-in structures are only suitable for structures that can be installed layer by layer, with each layer of planar structure assembled separately and the layers connected by plug-in members perpendicular to the layer plane. In this case, θ=0 can be regarded as the minimum L calculation formula mentioned above, which shows that it does not affect the installation at all. However, whether plug-in structures for multi-directional members in space can be installed, and what the requirements are for the installation steps, are questions that have not yet been addressed in the industry.

[0055] A multi-directional detachable equal-diameter circular tube insertion joint based on angle bisector cutting is disclosed. This joint is a key component connecting intersecting members. The joint comprises two or more members 2 and corresponding sleeves 1. "Corresponding" means that their centerlines are collinear and their outer diameters are the same. The members 2 and their corresponding sleeves 1 are connected via an insertion structure. This insertion structure refers to the member 2 having a reduced-diameter tube 3 at its end, inserted into the corresponding sleeve 1. A structural adhesive layer 4 is provided in the gap between the reduced-diameter tube and the sleeve. The sleeves 1 are connected at the intersection as a single unit. The intersection of the sleeves refers to the intersection of the center lines of sleeve 1 at point O. The area where this point is located is the intersection point. The intersection end of sleeve 1 is a polyhedral cone. The polyhedral cone is formed when the intersection end of the sleeves is considered solid and extends infinitely, and it is cut by other sleeves in the node along the corresponding angle bisector. Point (O) is the vertex. When the polyhedral cone is composed of two planes, point (O) is the midpoint of the intersection line. The angle bisector is the plane containing the angle bisector of the corresponding two sleeve center lines and the normal of the plane determined by the corresponding two sleeve center lines. The outer surface contour line of the polyhedral cone has a weld. The weld connects the sleeves in the node into a whole, which is the core component of this node. The sleeves connected by the weld are closed. The closure means that there are no misalignments, openings or collisions in the pipe wall, and both the inner and outer surfaces are closed. The rod 2 is a rigid round tube with the same outer diameter and a certain degree of plasticity. The end of the reduced-diameter tube 3 is flush-cut, and the end of the reduced-diameter tube 3 is also flush-cut. The flush-cut is a plane perpendicular to the center line of the rod 2. The sleeve 1 is a metal round tube with uniform wall thickness, and the tensile and compressive strength of the sleeve section is not less than the maximum tensile and compressive strength of the section of the rod 2 in the node. The sleeve 1 is flush-cut on the side closest to the corresponding rod 2. The length of the uncut part of the sleeve 1 should not be less than the insertion length of the reduced-diameter tube 3 of the rod.

[0056] Furthermore, the aforementioned polyhedral cone refers to the cone formed when the confluence of sleeves 1 is considered solid and extends infinitely, and it is cut along the corresponding angle bisector of other sleeves 1 in the node. Point (O) is the vertex, and when the polyhedral cone consists of two planes, point (O) is the midpoint of the intersection line. Because the intersection point of two intersecting lines determining the angle bisector is point (O), point (O) lies on all angle bisectors cutting the polyhedral cone, and further on the intersection line of any two angle bisectors. Since the members 1 do not coincide, any two angle bisectors are not parallel, and the intersection line must exist. The intersection line is also an edge of the polyhedral cone. Because all intersection lines intersect at point (O), point (O) is the vertex of the polyhedral cone. The cutting refers to cutting sleeves 1 through a plane so that all or part of sleeves 1 are located on one side of the cutting surface, retaining the side of member 2, without limiting the cutting depth or order. The cutting depth refers to the cutting surface being considered an infinitely extending plane, where the sleeves 1 cut by it will not stick together, and there will be no situation where only one cut is not completed, allowing all sleeves 1 to be located on one side of the cutting surface. The order refers to the fact that each sleeve 1 can be cut in any order with all other sleeves 1 in the core component, and the final cut head remains unchanged. This differs from the concave cutting surface of the cut head in the primary and secondary pipe intersection connection node of the prior art 1, where the secondary pipe is considered a solid.

[0057] Furthermore, the splice weld of the sleeve 1 is a semi-penetration weld. When the joint strength requirement is high, a fillet weld can be added to the outside to improve the welding strength. The splice seam can be seen from the inside. It has a different structure from the castings in the prior art 3 and 4.

[0058] Furthermore, the length of the reduced-diameter tube 3 at the end of the rod 2 should not be less than the corresponding sleeve diameter, and the end of the reduced-diameter tube 3 can be tapped for easy connection. The load-bearing capacity of the plug-in structure can be calculated according to the standard formula F=μ*σ*A, where σ is the structural adhesive strength, A is the corresponding contact area, and μ is the reduction factor (μ≤0.8). For example, for a sleeve with an inner diameter of φ25 and an insertion depth of 25mm, if epoxy resin AB glue with a shear strength (steel-to-steel) σ≥12Mpa is selected, and μ is taken as 0.8, its load-bearing capacity F=17.34KN; when the rod section is selected as φ25*0.75 and the material is Q304 stainless steel, its cross-sectional tensile and compressive load-bearing capacity =17.37 KN≈F. It can be seen that using structural adhesive layer 4 for connection can achieve equal strength connection for some thin-walled steel pipes. Even if equal strength connection is not achieved, the load-bearing capacity provided can meet the actual project requirements. The plug-in structure can also improve the stiffness of sleeve 1 to a certain extent without affecting the internal connection, which has additional benefits. The end of rod 2, the reduced diameter tube 3, is formed in one step using a hydraulic compression fitting machine, resulting in a beautiful and durable product.

[0059] Furthermore, the structural adhesive layer 4 must meet certain structural requirements. The structural adhesive is a slow-curing type. When the structure needs to be disassembled, epoxy AB adhesive or anaerobic threadlocker is selected, which has easy disassembly characteristics. When disassembly is required, a hot air gun is used to heat the insertion structure, causing the internal structural adhesive layer 4 to soften and fail, thus facilitating disassembly without damaging the structural paint film or causing surface oxidation and discoloration. The gap between the reduced-diameter tube 3 and the corresponding sleeve 1 must meet both the installation requirements (≥0.1mm) and the stress requirements of the structural adhesive layer 4, generally ≤1mm.

[0060] Furthermore, both ends of the aforementioned rod 2 are intersections of different rods, and can both serve as nodes. In three-dimensional space, the end of a rod 2 contains six degrees of freedom: movement along the x, y, and z axes, and rotation around the x, y, and z axes. In its local coordinate system, the direction of the centerline of rod 2 is considered the x-axis. The plug-in structure in the node can be considered a rigid connection within the load-bearing capacity range, completely restricting these six degrees of freedom of rod 2. Rotation around the x-axis is independently restricted by the structural adhesive layer 4. The misalignment at the transition point from the end of rod 2 to the reduced-diameter tube 3 provides positioning functionality along the x-axis. Because the structural adhesive layer 4 has slow-curing properties, the node installation does not restrict the rotation of the rod around the x-axis, which greatly reduces installation difficulty—a unique advantage of the plug-in structure. For example, existing threads cannot provide positioning functionality along the x-axis, and existing bolts restrict the rotation of the rod around the x-axis during installation, or although they do not restrict rotation around the x-axis, they cannot constrain rotation around the y and z axes. The plug-in structure should be considered an important component of this node.

[0061] Furthermore, the term "multi-directional" refers to multiple quantities and multiple directional angles, supporting the node construction at the intersection of two or more equal-diameter rods 2 in three-dimensional space, excluding overlap, at any spatial angle. For any rod 2 without the reduced-diameter tube 3 and a length L ≥ 0, the node is supported and can be installed. When rod 2 is too short and rod 2 and sleeve 1 are made of the same material, one side of rod 2 can be merged with sleeve 2, omitting the reduced-diameter tube 3 and structural adhesive layer 4 on that side. In this case, the wall thickness of rod 2 equals the wall thickness of the merged sleeve 1. When the length L of rod 2 without the reduced-diameter tube 3 is ≥ the calculation result of the following theoretical calculation formula a, it can be installed without using the overall scaling mode. (See attached...) Figure 10 Explanation: Let the insertion depth be L1, the insertion gap be d (one side fits tightly against the other side), the length of the rod excluding the constriction be L, and the angle between the moving direction of the core component at the mounting end and the direction of the rod be θ, then:

[0062] sinα=d / L1

[0063] ψ=θ-α

[0064] L = L1 * sinψ / (sinθ - sinψ)

[0065] The overall scaling mode described is a general principle for node installation, applicable to any spatial mesh structure using this node. The proof is as follows: The 3D model of the spatial mesh structure is enlarged as a whole. The core component moves with the node, and the rods move with their center points. During the enlargement process, the component dimensions and orientation remain unchanged, causing the rods to completely detach from the core component. This can be considered the state before installation. Then, the entire mesh is scaled down, returning to the initial state. This can be considered the installation process. During the scaling down, all rods sequentially contact their corresponding sleeves according to their inter-joint lengths from shortest to longest, and are successively inserted and tightened to complete the simulated installation. This proves that this multi-directional detachable equal-diameter circular tube insertion node can be installed for any spatial mesh structure. In actual installation, for ease of installation, there is a gap of approximately 50 micrometers between the outer diameter of the reduced-diameter tube portion of the rod in the insertion structure and the inner diameter of the corresponding sleeve. During installation, the shorter rods are installed first, followed by the longer rods, and all are tightened together. Installation is successful in all cases.

[0066] A specific application example of the theoretical calculation formula is as follows: When L1=25mm, d=0.5mm, and θ=30°, L=692.5mm is obtained. According to the formula, L is positively correlated with L1 and θ, negatively correlated with d, and independent of the diameter and wall thickness of the circular tube. When θ≤α, L≤0, which is considered to have no impact on installation. This formula is applicable to the situation where the core component on one side (side a) of member 2 is fixed, and the core component on the other side is movable. In actual installation, when the structural adhesive layer 4 at the node insertion point has not exceeded its initial curing time (0.15~2 hours), the core component on side a can also rotate slightly, and the actual L will be smaller than the theoretical value. From the specific application example, it can be seen that the minimum length L that does not affect installation is relatively easy to meet. The theoretical derivation of this overall scaling mode and the minimum L calculation formula are of great significance for the installation of this node and similar insertion nodes. It belongs to the invention point of this node and should be regarded as an innovation.

[0067] Furthermore, the hollow and interconnected nature of the core components, the hollow nature of rod 2, and the airtightness of the welded joints and plug-in structures of sleeve 1 give the structure formed by this node the characteristics of internal interconnection and enclosure. The problems of the intersection of multi-directional rods in space and the installation of the plug-in structure are mutually restrictive; only through collaborative research and development of theory and structure can breakthroughs be achieved. This is also the main technical problem that this utility model's node addresses. The following explanation, combined with the sleeve angle bisecting plane cutting and splicing process and the specific implementation steps of the node application, will illustrate these issues.

[0068] A process for cutting and splicing the sleeve angle bisector of a multi-directional detachable equal-diameter circular pipe insertion joint includes the following implementation steps:

[0069] S1. The angle bisector cutting method for the multi-directional detachable equal-diameter circular tube insertion node in modeling includes the following steps:

[0070] In this cutting method, the intersection of each sleeve 1 in the core component must be considered as infinitely extending before cutting. Then, it is cut along the bisector of the angle of the corresponding sleeve 1 with all other sleeves 1 in the core component. The cutting refers to cutting the sleeve through a plane so that all or part of the sleeve is located on one side of the cutting plane, while retaining the rod side. There is no restriction on the cutting depth and sequence.

[0071] Although this method may not have the fewest steps, for example, see Appendix Figure 6 The angle bisector shown in the DD view can be omitted, but applying this cutting method eliminates the need to analyze member intersections, making it versatile and easy to implement one-click automatic cutting of all nodes using software programming. This should be considered an innovation. The proof is as follows:

[0072] Given that the number of sleeves in the core component is n (n>2), and since the theoretical angle between any two sleeve centerlines in the core component is (0, 180°) in degrees, according to the angle bisector theorem, the theoretical angle between the sleeve centerline and their angle bisector is (0, 90°). That is, the theoretical angle between the sleeve centerline and the cutting surface (angle bisector) is (0, 90°). Therefore, when any sleeve is considered solid, the final cut is a convex polyhedron (composed of at least 2 planes and at most n-1 planes, excluding curved surfaces). When there is no concave polyhedron, there is no need to consider which specific cutting surfaces constitute the concave surface. Thus, cutting along the angle bisector does not restrict the cutting depth or order. Therefore, sleeves in a node can be cut even if they do not intersect, and the final cut remains unchanged. For example, cutting along the attached... Figure 6 As shown in the DD view, it is feasible to cut each sleeve along the corresponding sleeve angle bisector with the other n-1 sleeves.

[0073] S2. The angle bisection cutting process of the multi-directional detachable equal-diameter circular tube insertion node during blanking includes the following steps:

[0074] S2.1 For circular pipes with intersecting joints, traditional intersecting joints are often concave surfaces, making manual cutting difficult. Currently, the only practical method is to use an intersecting line cutting machine, which, while feasible, has high equipment costs. In this node's core component, each sleeve splice end is a convex polyhedron (when considered solid), supporting manual cutting and having low equipment dependence. For example, see attached... Figure 6This diagram shows the front sectional view of the separating member and its front view of the plane formed by the other five members. Based on this diagram, the sleeve G corresponding to the separating member can be cut. It can be seen from the diagram that the splicing end of sleeve G consists of four cutting planes, namely the angle bisector a in views BB, CC, EE, and FF. In view DD, sleeve G is entirely on one side of cutting plane a, requiring no actual cutting. By reading the relative torsion angles of the four views from view AA, and combining this with the intersection point (O) of the member centerlines in the corresponding views and the direction angle of angle bisector a, the end face of the sleeve can be cut using a cutting machine, thus achieving the cutting process. This cutting method is universal and applicable to the cutting of all sleeves at this node.

[0075] S2.2 The above-mentioned method for drawing the blanking diagram of sleeve 1 requires the assistance of views of other sleeves 1 in the core components. Regardless of whether sleeve 1 is actually cut, a cross-sectional view must be generated to obtain the information. Although it is intuitive and easy to understand, there is too much irrelevant information, and a certain amount of drawing experience is required to understand it. The following is a node matching theory that allows the creation of the blanking diagram of sleeve 1 using only the view of sleeve 1. This method is applicable to the blanking of the polyhedral cone of sleeve 1 in this node and should be considered an innovation.

[0076] S2.3, Appendix Figure 7 This is the cutting drawing for the sleeve corresponding to the separating rod. The view is a frontal sectional view of the polyhedral cone side, including the projection lines of the four angle bisectors, the angles between adjacent projection lines (19.5°, 85.5°, 43.7°), and the angles between the angle bisectors and the sleeve centerline (68.4°, 28.6°, 26.7°, 42.6°). Using this information, combined with the sleeve length information, the corresponding sleeve can be cut. Note: 1. The other four radius lines are the edge lines of the polyhedral cone, used to verify whether the cut style matches the view. Figure 1 2. The direction of the casing centerline is from the intersection side to the rod side, and the included angle is marked on the corner side of the angle bisector. All included angles are acute and do not have a direction.

[0077] S2.4, the following is in conjunction with the appendix Figure 8Taking the separated rod as an example, the following describes the innovative method for drawing the blanking diagram of this sleeve: 1. Draw section AA in the side view of the right sleeve to obtain the front section of the polyhedral cone side, and move its cone point (O) to the extension line of the sleeve centerline; 2. Find the point marked with length DL, and draw a perpendicular line from this point to the sleeve centerline (this point is the intersection of the edge line of the polyhedral cone and the outer contour line, the angle between the edge line where this point is located and the sleeve centerline is an acute angle, and the horizontal distance between this point and point (O) is the smallest relative to other matching points); 3. Obtain the intersection points of other edge lines and this perpendicular line (when the angle between the edge line and the sleeve centerline is an obtuse angle, it intersects with the extension line), and draw a line parallel to the sleeve centerline and the projection line (or the extension line of the projection line) of the corresponding edge line of the polyhedral cone on the left. 4. Connect the new points on the projection lines of the two adjacent edge lines, and draw a perpendicular line from point (O) to them. This perpendicular line is the projection line of the angle bisector in the angle bisector plane corresponding to the plane containing the two edge lines, and its pointing side is the side of the included angle label; 5. Copy the line segment corresponding to DL to the four perpendicular foot points, and draw a circle with DL as the radius to obtain the four new intersection points of the circle and the connecting line (or the extension of the connecting line) in step 4; 6. Connect point (O) with the new intersection points. The angle between this line segment and the connecting line in step 4 is the angle between the corresponding angle bisector and the center line of the sleeve. Label it on the outside of the corresponding perpendicular line; 7. Label the angle between the four perpendicular lines to obtain the angle between adjacent projection lines; 8. Organize the labels, delete useless elements, and the similar appendix is ​​now complete. Figure 7 The blanking diagram of the sleeve corresponding to the separating rod.

[0078] S2.5. The method for drawing the innovative blanking diagram for this sleeve is rigorous and supported by corresponding mathematical theories. The following is a detailed explanation in conjunction with the attached diagram. Figure 8Specific explanation: 1. Step 2 in the previous section is equivalent to obtaining a plane 'a' determined by the perpendicular line and the normal of the right-side view; 2. Step 3 in the previous section is equivalent to finding the intersection point of the edge line (or the extension of the edge line) of the polyhedron cone in three-dimensional space with plane 'a'. The projection points of the intersection points found in the AA section view are the four new points; 4. Because the sleeve centerline is perpendicular to plane 'a', the sleeve centerline is perpendicular to the line connecting the intersection points in plane 'a'. Because the perpendicular line made in step 4 in the previous section is perpendicular to the line connecting the new points, and plane AA is parallel to plane 'a', the perpendicular line made in step 4 in the previous section is also perpendicular to the line connecting the new points in plane 'a'. The line connecting the corresponding intersection points in plane a is perpendicular to plane b, which is determined by the sleeve centerline and the corresponding perpendicular line drawn in step 4 of the previous section. Since the line connecting the intersection points in plane a lies on plane c (or its extension) of a polyhedral cone in three-dimensional space, plane b is perpendicular to the corresponding plane c. 5. Plane c is the required cutting plane (angle bisector), and plane b is the cutting view. In plane b, plane c is a straight line. 6. Steps 5 and 6 of the previous section involve constructing a right triangle in plane b in the AA section view, thus obtaining the angle bisector and the sleeve centerline. This proof is rigorous; the extension line or extension surface will not change the cutting plane and will not affect the calculation results. This method is applicable to the drawing of blanking diagrams for all sleeves at this node.

[0079] S3. The angle bisector splicing process of the multi-directional detachable equal-diameter circular tube insertion node during assembly includes the following steps:

[0080] For multi-directional intersecting nodes in space, their feasibility largely depends on the success of the assembly and positioning process, regardless of whether it is completed during the manufacturing or construction phases. The sleeve construction in this node offers significant advantages in the assembly process, simplifying the most complex task – a technological breakthrough. The specific angle bisector splicing process is as follows: First, read the sleeve part number from the core component assembly drawing to locate the required cut sleeve; the assembly drawing does not require dimensioning. Then, taking the non-concave end of any sleeve as the fixed end, let's assume this non-concave end contains x planes. Each plane is obtained by cutting the angle bisector between this sleeve and another sleeve in the core component. Therefore, we can find x sleeves that connect to it. According to the sleeve cutting surface coincidence theorem, corresponding cutting surfaces must be equal. Randomly select one of the x connected sleeves and attempt to splice it with the cutting surface of the fixed sleeve; at least one plane will completely coincide. When more than one plane satisfies the condition, a unique splicing surface can be determined by combining the core component assembly diagram. Spot welding is then performed along the outer contour line of this splicing surface to fix it, completing the splicing of one sleeve. Similarly, the splicing of the remaining x-1 sleeves can be completed. At this point, using the fixed x+1 sleeves as the fixed ends, the remaining unfixed sleeves corresponding to the exposed outer planes of their non-concave ends are found and spliced ​​in the same way until all sleeves belonging to this core component are spliced ​​to the fixed ends. If the gap between a certain splicing surface is large, it can be fine-tuned to evenly distribute the gap among other splicing surfaces, thereby reducing errors. This completes the assembly and positioning work of the core component. Because an angle bisector necessarily corresponds to two sleeves, and the sleeve splicing ends are all cut along the angle bisector, the final core component will not have any exposed cut surfaces; it is closed.

[0081] The aforementioned theorem on the coincidence of sleeve cutting surfaces is referenced in Appendix. Figure 9 The proof is as follows:

[0082] Because the sleeve wall thickness and diameter are the same, and their centerlines intersect at a single point (O), it can be proven that the sleeve walls on the cut (joint) surfaces of any two sleeves coincide. (Appendix) Figure 9 The view is in plane OAB, where OA is the centerline of the right pipe, OB is the centerline of the left pipe, OC is the angle bisector of OA and OB, and the CC section is the corresponding cutting surface of the two pipes. Let point P be any point on the corresponding cutting surface of the right pipe, satisfying the condition that its distance to OA is d ≥ rt and d ≤ r, where r is the pipe radius and t is the pipe wall thickness. According to the angle bisector theorem, the distance from point P' projected onto point OAB in plane OAB to the lines OA and OB is equal. According to the Pythagorean theorem, the distance from point P to OB is also equal to d. Therefore, point P is also on the corresponding cutting surface of the left pipe. Conversely, it can be proven that any point in the left pipe is also in the right pipe. Thus, any cutting surface will not produce misalignment, openings, or collisions, and the corresponding cutting surfaces of the left and right pipes coincide, i.e., are equal.

[0083] The aforementioned angle bisector splicing process is applicable not only to manual splicing but also to fully automated splicing by robotic arms, with the steps remaining consistent. The first difference is that robotic arms achieve low-error results without fine-tuning, and the second is that while humans need to obtain information from the assembly drawings, robotic arms can directly obtain information from the model, eliminating the need for drawing generation. Subsequent welding operations can be performed using either manual tools or a fully automated welding robot.

[0084] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the specific implementation steps and with reference to the accompanying drawings.

[0085] First, structural selection is performed. Because this node supports the construction of nodes at the intersection of any number (2~n) of equal-diameter members at any spatial angle (excluding overlap) in three-dimensional space, there are no restrictions on the shape. Existing 3D modeling software (CAD, Rhino, SketchUp, Tekla, 3D3S, etc.) can be used for configuration design to determine the mesh structure. Then, based on project requirements and common material specifications in the market, the outer diameter and wall thickness of the members and sleeves are initially selected. When it is necessary to verify the safety of the structure, the following method is used.

[0086] When selecting structural members, all members converging at the same node must have the same outer diameter. A diameter change can be made in the middle of the member, and breaking one member into two new members with different diameters is considered a rigid connection (diameter change nodes are existing technology; pre-made tapered tubes can be purchased, or die stamping can be used). Because the structural load within the applicable range of this node is relatively small, the cross-section selected based solely on the appearance dimensions of the members is often large enough. With similar structural entities for verification, stress analysis can be directly determined without further stress analysis. When the structural configuration is novel or the load is large and the optimal cross-section needs to be determined, the spatial grid structure of this node is used. Stress analysis can be performed using existing structural calculation software (such as 3D3S) according to conventional spatial grid structures. The assumptions of rigid and hinged connections are specified according to industry standards based on different structural types and grid arrangements. Members must meet the requirements for slenderness ratio and diameter-to-thickness ratio of steel pipes in the "Steel Structure Design Standard GB50017-2017". The stress ratio control value is determined according to the secondary pipe bearing capacity / f (tensile and compressive strength of the main pipe) in the corresponding existing technology 1 of this standard. The maximum steel pipe cross-section in the node calculated using this method is taken as the minimum cross-section of the sleeve in that node. For structures within the applicable scope of this node, it can be considered as having only secondary pipes and no main pipes. For example, in the case of applying formula 13.3.2-1 of the standard, when the main and secondary pipe cross-sections are the same, assuming the minimum stress ratio of the main pipes on both sides of the node is minσ / fy = 0.092, the included angle θ = 90°, and the sleeve wall thickness t = 1mm, the calculated design value of the secondary pipe bearing capacity is Ncx = 27.82f. When the sleeve diameter R = 25mm, the estimated stress ratio of the secondary pipe bearing capacity is 0.0922, which is independent of the material f. In this case, 0.09 can be taken as the estimated maximum stress ratio of the sleeve.

[0087] Then, after reducing the wall thickness of the circular tube and adjusting the material and Poisson's ratio, a stress analysis is performed again. The stress ratio of the tube is controlled within 0.5 to determine the tube specifications. When the tube is made of steel, it needs to meet the requirements of the specification regarding the diameter-to-thickness ratio of steel tubes. Then, based on the maximum internal force under the combined working conditions of the tubes, the minimum contact area A of the structural adhesive layer of the tube can be determined, and the minimum diameter-reduced tube length L1 can be calculated.

[0088] The initial selection is now complete. However, since both the existing technology 1 and this node are beyond the scope of the standard for most spatial grid structures, it is necessary to verify the structural bearing capacity through simulated load experiments. Because the applicable scope of this node determines that its structural dimensions are relatively small and the structural load is relatively small, the safety of the structure can be verified by directly applying a simulated load of ≥1.5 times the calculated load to the solid structure.

[0089] Regarding the importance of experimental verification: Because the standard calculation of the secondary member's bearing capacity is based on the primary member, the cutting of the primary member will definitely affect the secondary member's bearing capacity. Therefore, the bearing capacity of the secondary member calculated using the standard is too high for the sleeve of this node and cannot replace experimental verification. While existing finite element analysis software can calculate the forces on this node, the stiffness of this node differs from the stiffness of type 1 nodes in the standard. The internal force values ​​calculated by the stress analysis software may not be accurate enough. When used for finite element analysis, a certain amplification factor needs to be considered. As a reference for typical nodes, experimental verification is still the most reliable method. This is the standard verification method for the applicable field of this node.

[0090] Then, modeling, detailed drawing, and material preparation of the members and nodes are carried out. The industry term is detailed design work, a time-consuming and labor-intensive process. A good node type should possess universality, be supported by mathematical theory, ensure node consistency, and avoid differences in node styles due to varying understandings among technical personnel in the relevant field. It should also possess certain efficiency advantages, and this node type embodies these advantages. Traditional existing technologies, such as node type 1, generally require specific analysis for different intersection situations, distinguishing between primary and secondary members, identifying which members need connection and which do not, and differentiating between secondary members based on stress and cross-section to determine which is not cut at the bottom and which is cut at the intersection line at the top. This is a very time-consuming task requiring data support from multiple processes. In contrast, the splicing surface cutting of the sleeves in this node follows a universality principle: each sleeve in the core component is cut along the corresponding sleeve angle bisector with other sleeves, without restrictions on cutting depth or order. This is described in detail in S1, which greatly improves node detailing efficiency and ensures the consistency of the detailed nodes. The process of further refinement also needs to meet the relevant structural requirements of the aforementioned sleeve, insertion structure, and structural adhesive layer.

[0091] Then comes the structural processing. This includes material procurement, cutting, assembly, welding, tube shrinking, painting, and packaging, which constitutes the product manufacturing process. There are two main difficulties: first, the cutting of the sleeve is described in detail in S2; second, the assembly of the core components is described in detail in S3. The others can be achieved using existing technologies.

[0092] Then, the construction of the structure is carried out. This includes transportation, installation, and acceptance, which is the application stage of the product. The plug-in structure has its advantages and disadvantages. The disadvantage is that, because the reduced-diameter tubes at both ends of the members need to be inserted into the corresponding sleeves, during installation, the members in the structure need to be classified by length according to the overall scaling mode and the minimum L calculation formula that does not affect installation, as disclosed in the utility model content, to determine the installation sequence, and then install them sequentially. The advantages are: traditional welding connections are difficult to position, the welding area needs grinding and touch-up painting, and the construction difficulty is high; traditional bolt connections are mostly suitable for hinged or planar structures, requiring consideration of the member torsional angle matching, and have limited support for spatial grid structures. Furthermore, when using high-strength bolts, because the contact surface is not painted, touch-up painting is required after connection, making construction difficult; traditional threaded connections are not suitable for spatial grid structures. Comparative analysis shows that the nodes in this application have the advantages of connection without damaging the surface, no need to consider the member torsional angle, simple operation steps, extremely low requirements for installation tools and equipment, and extremely low requirements for rigidity and angle assembly jigs. The reduced diameter at both ends of the members facilitates both connection and determination of member length, making them easy to install.

[0093] (5) Finally, it supports disassembly when necessary. Structural adhesives are widely used in the bonding of materials such as metals, ceramics, plastics, rubber, and wood, and can partially replace traditional connection methods such as welding, riveting, and bolting. This node is an innovation in its application scope. It provides the node with load-bearing capacity support, airtightness support, cold connection protection against skin damage support, and disassembly support, and is an essential component of node connection.

[0094] This is a specific implementation step of a spatial grid structure using the nodes of this application. It not only includes a complete structural construction process, but also contains unique theoretical support. It is a utility model with completeness and innovation.

[0095] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0096] Example 1:

[0097] The nodes are easy to install and can be removed. For example, attached... Figure 11This is a membrane structure tent, with an outer single-layer reticulated shell structure using the nodes described in this application, and an inner membrane structure. It has 60 supports and 10 pedestals. When other members are considered as closed curved reticulated shell structures, the number of edges E = 175 and the number of vertices V = 67. According to Euler's formula, the number of faces F = 2 + EV = 110 (including the bottom and door). During installation, the single-layer reticulated shell is installed first, and the interlocking structures are secured with structural adhesive. After 24 hours, once the adhesive has reached its strength, the membrane structure is installed from the inside. The membrane structure tensioning nodes are secured with bolts and additional nuts in the inner sleeves of the core components of the corresponding application nodes. The membrane structure applies centripetal force to the outer single-layer reticulated shell structure, which can improve the overall load-bearing capacity of the structure. The combined structure has a reasonable stress distribution, large internal space, strong wind and snow resistance, is easy to install, and all nodes are detachable for easy disassembly. It is lightweight, portable, and reusable.

[0098] Example 2:

[0099] The nodes are not limited in the number or angle of equal-diameter steel pipes and are easy to transport, for example, with... Figure 12 The sculpture is a large bear with a polyhedral outline, belonging to a closed curved reticulated shell structure. Its number of edges E = 868, number of vertices V = 298, and according to Euler's formula, the number of faces F = 2 + EV = 572. There are various node combinations, with the fewest nodes containing 3 members and the most containing 12 members. It is 6.12m long, 2.9m wide, and 3.75m high. The sleeve is made of φ25*1.5 stainless steel pipe, and the members are made of φ25*1 stainless steel pipe. The longest node spacing is 1.68m, and the radius of gyration is 0.84cm. The calculated slenderness ratio of the members is 168 / 0.84 = 200, meeting the specifications. The ratio of the outer diameter to the wall thickness of the steel pipe is 50 < 100εk² = 113.7, also meeting the specifications. Due to the relatively low stress in the members, only structural requirements need to be met. For some members that are too short, one end of the member is merged with the corresponding sleeve, while the other side is constructed as a reduced-diameter pipe connected to the corresponding sleeve. Its shipping volume is within 1.5 square meters and its weight is within 320 kg. However, if transported as a whole, the assembled external cuboid would have a volume of 66.6 square meters, exceeding the width and height limits, requiring transportation in sections and resulting in high transportation costs. Adopting a shipping model that combines easily assembled rods with core components can significantly reduce transportation costs.

[0100] Example 3:

[0101] The nodes support unconventional spatial meshes and rigid connections. Regardless of whether it's Example 1, Example 2, or a single-layer mesh, double-layer mesh, or three-dimensional truss, the connecting members can form a planar ring without any other members passing through it; this is simply called a planar ring mesh. This type of mesh can use panels to replace the members; for example, Example 2 has a corresponding polyhedral sculpture. However, similar to the applicant's design... Figure 13The round-top, square-bottom table, with its supporting structure consisting of two planar rings (top and bottom), has no other members that can form planar rings. Therefore, a panel cannot replace the rod structure, making it a unique structural type. This round-top, square-bottom table's supporting structure has 20 edges (E = 20) and 12 vertices (V = 12). This structure requires at least some members to be rigidly connected to form a geometrically invariant form. This node can be considered rigidly connected under low loads, capable of transmitting shear force, axial force, bending moment, and torque, making it an ideal node for similar structures.

[0102] Example 4: Self-supporting pipeline transportation or pipeline structure.

[0103] The airtightness of the hollow structure inside the nodes, the hollow structure of the rods, and the plug-in structure gives the structures formed by these nodes both internally connected and closed. This makes them suitable for pipeline transportation under low internal and external pressure differences or as water-proof conduits in pipelines, and they also possess a certain degree of self-supporting capacity. For example, attached... Figure 14 The structure is a time tunnel project (a decorative lighting structure) with a radius of 9.5m and an arch height of 3.96m. The poles are made of φ32*2mm colored semi-transparent PC rigid pipes, and the sleeves are made of 1.5mm thick stainless steel pipes. The internal lighting strips are installed, which have the advantages of being waterproof, beautiful, and self-supporting.

[0104] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0105] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multi-directional detachable equal-diameter circular tube insertion joint based on angle bisector cutting, wherein the joint is a key component connecting intersecting rods together, characterized in that... The node includes two or more rods (2) and sleeves (1) corresponding to the rods (2). The term "corresponding" means that the center lines are collinear and the outer diameters are the same. The rods (2) and the corresponding sleeves (1) are connected by a plug-in structure. The plug-in structure means that the end of the rod (2) is a reduced-diameter tube (3) inserted into the corresponding sleeve (1). A structural adhesive layer (4) is provided in the gap between the reduced-diameter tube and the sleeve. The sleeves (1) are connected as one unit at the intersection. The term "intersection" means that the center lines of the sleeves (1) are aligned. The two ends of the sleeves (1) intersect at point 1 (O). The area where this point is located is the intersection point. The intersection end of the sleeves (1) is a polyhedral cone. The polyhedral cone is formed when the intersection end of the sleeves is considered solid and extends infinitely. It is cut by the other sleeves in the node along the corresponding angle bisector. Point (O) is the vertex. When the polyhedral cone is composed of two planes, point (O) is the midpoint of the intersection line. The angle bisector is the plane containing the angle bisector of the center lines of the two sleeves and the normal of the plane determined by the center lines of the two sleeves. The outer surface contour of the polyhedral cone has a weld. The weld connects the sleeve in the node into a whole as the core component of this node. The sleeve connected by the weld is closed. The closure means that there is no misalignment, opening or collision of the pipe wall and the inner and outer surfaces are closed. The rod (2) is a rigid round tube with the same outer diameter and a certain plasticity. The end of the reduced diameter tube (3) is flush. The end of the reduced diameter tube (3) is also flush. The flush is a plane perpendicular to the center line of the rod (2). The sleeve (1) is a metal round tube with uniform wall thickness and the tensile and compressive strength of the sleeve section is not less than the maximum tensile and compressive strength of the section of the rod (2) in the node. The sleeve (1) is flush on the side close to the corresponding rod (2). The length of the uncut part of the sleeve (1) should not be less than the insertion length of the reduced diameter tube (3) of the rod.

2. The multi-directional detachable equal-diameter circular tube insertion node based on angle bisector cutting according to claim 1, characterized in that... The length of the reduced-diameter tube (3) at the end of the rod (2) should not be less than the corresponding sleeve diameter.

3. A multi-directional detachable equal-diameter circular tube insertion node based on angle bisector cutting according to claim 1, characterized in that... The structural adhesive layer (4) is a slow-curing structural adhesive. When the structure needs to be disassembled, epoxy AB glue or anaerobic threading glue is selected. It has easy disassembly characteristics. When disassembly is required, the structural adhesive layer (4) can be heated to pull out the rod and realize the separation of the node. The gap between the rod diameter reduction tube (3) and the corresponding sleeve (1) is ≥0.1mm and ≤1mm.

4. A multi-directional detachable equal-diameter circular tube insertion node based on angle bisector cutting according to claim 1, characterized in that... The core component is hollow and connected, and the rod (2) is hollow.

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