Multidirectional detachable equal-diameter round pipe inserting joint based on angular bisection surface cutting

Abstract

A multidirectional detachable equal-diameter round pipe inserting joint based on angular bisection surface cutting is characterized in that multidirectional refers to a joint structure at the junction of a plurality of equal-diameter round pipe rod pieces which are provided with multiple numbers and multiple directional angles and support any space angle except for two or more overlapped space angles in a three-dimensional space, and the joint comprises rod pieces (2) and sleeves (1) corresponding to the rod pieces (2). The rod piece (2) is connected with the corresponding sleeve (1) through an inserting structure, the inserting structure is that the end part of the rod piece (2) is provided with a reducing pipe (3) which is inserted into the corresponding sleeve (1), a structural adhesive layer (4) is arranged in a gap between the reducing pipe and the sleeve, and the sleeve (1) is connected into a whole at the intersection. The invention has the characteristics of strong universality, easiness in model selection, easiness in processing, easiness in transportation, easiness in construction, no maintenance, internal communication and good air tightness, and is an ideal node for expanding conception in the fields of temporary building of building steel structures, landscape decoration, furniture brackets, pipeline structures and lamp tube decoration.

Description

Technical Field

[0001] The invention relates to the fields of temporary construction of building steel structures, landscape decoration, furniture brackets, pipeline structures and lamp tube decoration, and in particular to a connection node of a space grid structure. Background Art

[0002] Steel pipe is a commonly used material in the field of steel structure, with complete market specifications and easy to purchase. The steel pipe mentioned here refers to metal round pipes, excluding square pipes and rectangular pipes. For fields such as building steel structure where material costs account for a high proportion, different outer diameters of steel pipes are more conducive to saving materials. According to the calculation formula for direct welding nodes of steel pipes in the "Steel Structure Design Standard GB50017-2017", the bearing capacity of the branch pipe at the node is far less than the cross-sectional bearing capacity of the main pipe. This limits the application of direct welding nodes of steel pipes in spatial grid structures from the perspective of force, resulting in the entire industry not exploring the application potential of equal-diameter steel pipes in spatial grid structures under low-load conditions. For fields such as temporary construction of building steel structures, landscape decoration, furniture brackets, pipeline structures and lamp decorations, where the load is small, the material cost accounts for a small proportion, and the labor cost accounts for a high proportion, there is a lack of a universally applicable spatial grid node. Considering aesthetic factors, the material cannot be too thin. Under low load conditions, the stress of the rod is far less than its maximum bearing capacity. The bearing capacity requirements of the rod node are relatively low, and the universality, easy transportation, easy installation and detachability of the node are relatively high. However, due to the lag between theory and actual needs, there is no node that can have these advantages at the same time. The advantages and disadvantages of the space grid circular tube connection node in 5 existing technologies are explained below: The first type is the node where the main and secondary pipes intersect. There is no independent node core component in the structure. The intersection of the rods is welded. There is a main rod and several secondary rods. The main rod is continuous, and the secondary rods are welded after the intersection is close to the main pipe. The advantage is that the diameter of the main pipe can be greater than the diameter of the secondary pipe, and the bearing capacity is good; the disadvantage is that the positioning of the main and secondary pipes is difficult, the installation accuracy is low, and the processing of the intersection of the rods is difficult. Fig.15 shown.

[0003] The second type is the welded ball node, which has an independent node core component in the structure, generally a hollow steel ball, which is welded to the rod. The advantages are that the core component is independent, easy to process, the rod is straight and easy to cut, and the bearing capacity is good; the disadvantage is that it is only applicable when the rod angle is large. When the rod angle is small, the diameter of the welded ball increases sharply, affecting the appearance and bearing capacity. Fig.16 shown.

[0004] The third type is cast steel and 3D printed nodes, which have independent node cores in the structure and are formed in one piece. The advantages are universality, independent node core components, easy transportation, straight rods for easy cutting, and good bearing capacity; the disadvantages are that the node core components are heavy, the processing cost is high, and the design is difficult. Fig.17 shown.

[0005] The fourth type is a specific angle sleeve node, which is mostly suitable for furniture brackets, pipeline transportation, etc. It supports several specific connection angles of 45, 60, and 90 degrees and a specific number of connecting rods. The advantages are low batch processing costs, easy transportation, and easy installation; the disadvantages are that the application range of fixed angles and fixed rods is limited. Fig.18 shown.

[0006] The fifth type is the steel pipe oblique joint, which refers to the joint where two equal-diameter steel pipes are welded together after being spliced ​​at an oblique angle. The advantage is that it is easy to process; the disadvantage is that the number of rods is limited, and there is no independent node core component, which makes on-site splicing difficult. Fig.19 shown.

[0007] Combining 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 are all difficult to install and position. The application scope of specific angle casing nodes and steel pipe bevel splicing nodes is limited. For equal-diameter circular tubes, there is no universal connection node that is unlimited in the number of rods, unlimited in the angle of rods and easy to install. The appearance here not only refers to the appearance in reality, but also refers to the appearance in related mathematical theory. Summary of the invention

[0008] The present invention is to fill the gap in the industry and proposes a multi-directional detachable equal-diameter circular tube plug-in node based on angle bisector cutting. The node is a key part that connects the rods at the intersection. It is characterized in that the node includes more than two rods (2) and sleeves (1) corresponding to the rods (2). The correspondence refers to the center lines being collinear and having the same outer diameter. The rods (2) and the corresponding sleeves (1) are connected through a plug-in structure. The plug-in 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 a whole at the intersection. The intersection refers to the center lines of the sleeves (1) intersecting at a point (O). This point is located The area is the intersection, the intersection end of the sleeve (1) is a polyhedral pointed cone, the polyhedral pointed cone means that when the intersection end of the sleeve is regarded as solid and infinitely extended, it is cut with other sleeves in the node along the corresponding sleeve angle bisector plane, with point (O) as the vertex, when the polyhedral pointed cone is composed of two planes, point (O) is the midpoint of the intersection line, the angle bisector plane is the plane where two intersecting straight lines of the angle bisector corresponding to the center lines of the two sleeves and the normal of the plane determined by the center lines of the two sleeves are located, there is a weld on the outer surface contour line of the polyhedral pointed cone, the weld connects the sleeves in the node as a whole and is the core component of this node, the sleeves connected by the weld are closed, and the closure means that there is no misalignment, opening or collision in the pipe wall, and the inner and outer surfaces are closed. The rod (2) is a hard circular tube with the same outer diameter and a certain plasticity, and the end of the necking tube (3) is flush at the diameter change point, and the end of the necking tube (3) is also flush, and the flush is a plane perpendicular to the center line of the rod (2). The sleeve (1) is a metal circular tube with a uniform wall thickness and the tensile and compressive strength of the cross section of the sleeve is not less than the maximum tensile and compressive strength of the cross section of the rod (2) in the node. The sleeve (1) is flush on the side close to the corresponding rod (2), and the length of the uncut part of the sleeve (1) should not be less than the plug-in length of the rod reducer (3).

[0009] Furthermore, the polyhedral cone refers to the cutting of the corresponding sleeve (1) angle bisector plane with other sleeves (1) in the node when the intersection end of the sleeve (1) is regarded as solid and infinitely extended, with point (O) as the vertex. When the polyhedral cone is composed of two planes, point (O) is the midpoint of the intersection line. Because the intersection point of the two intersecting straight lines that determine the angle bisector plane is point (O), point (O) is on all angle bisector planes that cut the polyhedral cone, and then on the intersection line of any two angle bisector planes. Because the rods (1) do not overlap, any two angle bisector planes are not parallel, and the intersection line must exist. The intersection line is also the edge of the polyhedral cone. Because all the intersection lines intersect at one point (O), point (O) is the vertex of the polyhedral cone. The cutting refers to cutting the sleeve (1) through a plane so that the sleeve (1) is completely or partially located on one side of the cutting plane, retaining the rod (2) side, and not limiting the cutting depth and sequence. The cutting depth means that the cutting surface can be regarded as an infinitely extended plane, and the sleeve (1) cut by it will not stick together, and there will not be a situation where only one incision is not cut, and the sleeve (1) can be located entirely on one side of the cutting surface. The order means that each sleeve (1) can be cut in any order when cutting all other sleeves (1) in the core component, and the final cut head remains unchanged. This is different from the concave cutting surface of the cut head when the secondary pipe is regarded as a solid in the primary and secondary pipe intersection connection node in the prior art 1.

[0010] Furthermore, the joint weld of the sleeve (1) is a semi-penetration weld, and when the node strength requirement is high, a fillet weld can be added on the outside to improve the welding strength, and the joint seam can be seen from the inside. This has a different structure from the castings in the prior art 3 and 4.

[0011] 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 neck tube (3) can be closed for easy connection. The bearing capacity of the plug-in structure can be calculated according to the standard formula F=μ*σ*A, where σ is the strength of the structural adhesive, A is the corresponding contact area, and μ is the reduction coefficient (μ≤0.8). For example, the inner diameter of the φ25 sleeve is φ23, the plug-in depth is 25mm, and the epoxy resin AB glue with shear strength (steel-steel) σ≥12Mpa is selected, and μ is 0.8, and its bearing capacity F=17.34KN; when the cross section of the rod is φ25*0.75 and the material is Q304 stainless steel, its cross-sectional tensile and compressive bearing capacity = 17.37 KN≈F. It can be seen that the structural adhesive layer (4) can achieve equal strength connection for some thin-walled steel pipes. Even if it cannot achieve equal strength connection, the bearing capacity provided can meet the actual project requirements. The plug-in structure can also improve the rigidity of the sleeve (1) to a certain extent without affecting the internal connection, which has additional benefits. The end necking tube (3) of the rod (2) is processed by a hydraulic necking machine for one-step molding, which is beautiful and durable.

[0012] Furthermore, the structural adhesive layer (4) must meet certain structural requirements. The structural adhesive is a slow-curing structural adhesive. When the structure needs to be disassembled, epoxy AB adhesive or anaerobic thread adhesive is selected, which has the characteristic of easy disassembly. When disassembly is required, a hot air gun is used to heat the plug-in structure so that the internal structural adhesive layer (4) softens and fails, thereby making it easy to disassemble without causing damage to the structural paint film or oxidation and discoloration of the surface. The gap between the rod necking tube (3) and the corresponding sleeve (1) must meet the installation requirement of ≥0.1mm and the force requirement of the structural adhesive layer (4), generally ≤1mm.

[0013] Furthermore, the two ends of the rod (2) belong to the intersection of different rods and can be used as nodes. The end of a rod (2) in three-dimensional space contains 6 degrees of freedom, which are 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 center line of the rod (2) is regarded as the x-axis. The plug-in structure in the node can be regarded as a rigid connection within the bearing capacity range, completely restricting the 6 degrees of freedom of the rod (2), wherein the rotation around the x-axis is independently restricted by the structural adhesive layer (4), wherein the misalignment at the transition from the end of the rod (2) to the neck tube (3) provides the rod (2) with a positioning function along the x-axis. Since the structural adhesive layer (4) has a slow curing characteristic, the rod is not restricted from rotating around the x-axis during node installation, which can greatly reduce the difficulty of installation. This is a unique advantage of the plug-in structure. For example, the thread in the prior art cannot provide a positioning function along the x-axis, and the bolt in the prior art will restrict the rod from rotating around the x-axis during installation, or although it does not restrict the rod from rotating around the x-axis, it cannot constrain the rod from rotating around the y and z axes. The plug-in structure described should be regarded as an important component of this node.

[0014] Furthermore, the multi-directional refers to multiple numbers and multiple directional angles, and supports the node structure at the intersection of two or more equal-diameter rods (2) in three-dimensional space at any spatial angle except for overlap. For any rod (2) with a length L ≥ 0 without a reducer (3), the nodes are supported and can be installed. When the rod (2) is too short and the rod (2) and the sleeve (1) are made of the same material, one side of the rod (2) can be merged with the sleeve (2), and the reducer (3) and the structural adhesive layer (4) of the rod on this side can be omitted. In this case, the wall thickness of the rod (2) = the wall thickness of the sleeve (1) merged with it. When the length L of the rod (2) without the reducer (3) ≥ the result of the following theoretical calculation formula a, it can be installed without adopting the overall scaling mode. Combined with the attached Fig.10 Note: Assume that the insertion depth is L1, the insertion gap is d (one side is close to the gap on the other side), the length of the rod excluding the shrinkage is L, and the angle between the moving direction of the core component at the installation end and the direction of the rod is θ, then: sinα=d / L1 ψ=θ-α L=L1* sinψ / (sinθ-sinψ) The overall scaling mode is a general principle for node installation, which is applicable to any spatial grid structure to which this node is applied. The proof is as follows: the three-dimensional model of the spatial grid structure is enlarged as a whole, the core component moves with the node, and the rod moves with the center point of the rod. The size and direction of the components remain unchanged during the enlargement process, so that the rod and the core component are completely disconnected, which can be regarded as the state before installation. Then the overall grid is reduced and returned to the initial state, which can be regarded as the installation process. During the reduction process, all the rods contact the corresponding sleeves in order from short to long according to the length of the internode, and are successively plugged and tightened to complete the simulated installation. It can be proved that for any spatial grid structure, this multi-directional detachable equal-diameter circular tube plug-in node can be installed. In the actual installation process, for the convenience of installation, the outer diameter of the rod reduction pipe part in the plug-in structure has a gap of about 50 threads with the inner diameter of the corresponding sleeve. During the installation process, the short rods are installed first, and then the long rods are installed in sequence, and they are tightened in coordination, and they can be installed normally.

[0015] A specific application case of the theoretical calculation formula is as follows: when L1=25mm, d=0.5mm, θ=30°, L=692.5mm is obtained. According to the formula, L is positively correlated with L1 and θ, negatively correlated with d, and has nothing to do with the diameter and wall thickness of the round tube. When θ≤α, L≤0, which is considered to have no effect on the installation. This formula is applicable to the case where the core component on one side (side a) of the rod (2) is fixed and the movable core component on the other side is installed. In actual installation, when the structural adhesive layer (4) at the node joint does not exceed its initial solidification time (0.15~2 hours), the core component on side a can also be slightly rotated, and the actual L will be smaller than the theoretical value. From the specific application case, it can be seen that the minimum length L that does not affect the installation is relatively easy to meet. The theoretical derivation of this overall scaling mode and the minimum L calculation formula are of great significance to the installation of this node and similar plug-in nodes. They belong to the invention point of this node and should be regarded as an innovation.

[0016] Furthermore, the core component is hollow and interconnected inside, the rod (2) is hollow inside, and the sleeve (1) has the advantages of airtightness of the joint weld and plug-in structure, so that the structure composed of the nodes has the characteristics of being internally interconnected and closed.

[0017] The beneficial effects of the present invention are: The node of the present invention has the characteristics of strong universality, easy selection, easy processing, easy transportation, easy construction, maintenance-free, internal connectivity and good airtightness. It is an ideal node for expanding the conception in the fields of temporary construction of building steel structures, landscape decoration, furniture brackets, pipeline structures and lamp tube decoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a perspective structural diagram of an implementation form of the multi-directional detachable equal-diameter circular tube plug-in node of the present invention; Figure 2 yes Figure 1 As the top view of the main view; Figure 3 yes Figure 1 Right view as main view Figure 4 yes Figure 1 Back view as main view Figure 5 yes Figure 1 Outline drawing of the view direction Figure 6 yes Figure 1 Front section of the separated rod and the front view of the plane formed by it and the other five rods Figure 7 yes Figure 1 Innovative cutting diagram of casing corresponding to the middle separation rod Figure 8 yes Figure 1 The process diagram of drawing the innovative cutting diagram of the casing corresponding to the separated rod and the illustration of the theoretical proof; Fig. 9 It is a diagram that proves the conclusion that the pipe walls on the cut surfaces of any two casing pipes coincide with each other; Fig.10 It is a diagram of the theoretical calculation formula for calculating the minimum length of the rod that does not affect installation; Fig.11 This is a schematic diagram of the membrane structure tent structure described in Example 1; Fig.12 This is a schematic structural diagram of the polyhedral outline bear sculpture described in Example 2; Fig.13 This is a schematic diagram of the structure of the round and square table described in Example 3; Fig.14 It is a schematic diagram of the structure of the space-time channel project described in Example 4; Fig.15 It is a structural schematic diagram of a connection node of a primary and secondary pipe intersecting line of the prior art form 1 described in the background technology of the present invention; Fig.16 It is a structural schematic diagram of a welding ball node of the prior art form 2 described in the background technology of the present invention; Fig.17 It is a structural schematic diagram of the prior art form 3 cast steel and 3D printed node described in the background technology of the present invention; Fig.18 It is a structural schematic diagram of a specific angle casing node of the prior art form 4 described in the background technology of the present invention; Fig.19It is a structural schematic diagram of the steel pipe oblique splicing node of the prior art form 5 described in the background technology of the present invention; Reference numerals: 1——Casing; 2 – rod; 3——reduced diameter pipe; 4——Structural adhesive layer; a——The cutting surface at the casing joint position is an angle bisector surface; b——Schematic diagram of the connection between the rod and the core component sleeve; c——Schematic diagram of the arc transition at the rod reduction tube; d——Instrument for closing the end of the rod reducer for easy installation; e——The connecting end faces of the rod and the sleeve are flush; O——intersection point of center lines of bars; DETAILED DESCRIPTION

[0019] The intersection of multi-directional rods in space has always been a difficult problem in the industry. In practical applications, the configuration design is often carried out according to the applicable scope of the nodes listed in the prior art 1~5, which greatly limits the configuration diversification of the spatial grid structure. A good multi-directional rod intersection node type should not limit the number of rods and spatial angles, have the principle of universality, be supported by mathematical theory, and be able to ensure the consistency of the node. It should not lead to different deepening node styles due to different understandings of technicians in the field. It should also have certain efficiency advantages and cost advantages. This node is a node type with these advantages. The reason why there is no similar node in the industry is that the plug-in structure has its advantages and shortcomings. The shortcoming is that the existing technology does not solve the installation problem of the plug-in structure of multi-directional rods in space. The inherent impression of the industry has always been that the plug-in structure is only applicable to structures that can be installed layer by layer. Each layer of the plane structure is assembled separately, and the layers are connected by rods perpendicular to the layer plane. At this time, it can be regarded as θ=0. According to the above minimum L calculation formula, it can be obtained that it does not affect the installation at all at this time. However, can the plug-in structure of multi-directional rods in space be installed and what are the requirements for the installation steps? There is no relevant theory in the industry yet.

[0020] The intersection of multi-directional rods in space and the installation of plug-in structures are two problems that restrict each other. Only the coordinated development of theory and structure can make a breakthrough. This is also the main technical problem that the node of the present invention solves. The following is an explanation of the specific implementation steps of the casing angle bisector surface cutting and splicing process and node application.

[0021] A sleeve angle bisector plane cutting and splicing process for a multi-directional detachable equal-diameter circular tube plug-in node comprises the following implementation steps: S1. The angle bisector plane cutting method in modeling of the multi-directional detachable equal-diameter circular tube plug-in node comprises the following steps: In this cutting method, the intersection end of each sleeve (1) in the core component must be regarded as infinitely extended before cutting, and then all other sleeves (1) in the core component are cut along the corresponding sleeve (1) angle bisector plane. The cutting refers to cutting the sleeve through a plane so that the sleeve is completely or partially located on one side of the cutting surface, retaining the rod side, and not limiting the cutting depth and sequence.

[0022] Although this method does not necessarily have the least number of steps, Figure 6 The angle bisector plane shown in the DD view can be omitted, but the application of this cutting method can avoid the analysis of the intersection of bars, has universality, and is also convenient for one-click full-node automatic cutting using software programming, which should be regarded as an innovation. The proof is as follows: It is known that the number of sleeves in the core component is n (n>2). Since the theoretical angle range between the center lines of any two sleeves in the core component is (0,180), in degrees, according to the angle bisector theorem, the theoretical angle range between the center line of the sleeve and their angle bisector is (0,90), that is, the theoretical angle range between the center line of the sleeve and the cutting surface (angle bisector) is (0,90). It can be obtained that when any sleeve is regarded as solid, the final cut head 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 make up the concave surface, and it can be obtained that cutting along the angle bisector does not limit the cutting depth and order. Therefore, the sleeves in the node can be cut even if they do not intersect, and the final cut head remains unchanged. For example, along the attached Figure 6 The angle bisector plane cutting shown in the DD view in the middle, it is feasible to cut each sleeve along the corresponding sleeve angle bisector plane with the other n-1 sleeves.

[0023] The angle bisector cutting process of the multi-directional detachable equal-diameter circular tube plug-in node in cutting includes the following steps: S2.1. For circular tubes with intersecting ports, because the traditional intersecting ports are often concave surfaces, they are difficult to cut manually. The only practical method in the prior art is to use an intersecting line cutting machine for cutting. Although it can be implemented, the equipment investment cost is relatively high. Each splicing end of the sleeve in the core component of this node is a convex polyhedron (when regarded as solid), which supports manual cutting and has a low degree of dependence on equipment. For example, the attached Figure 6This is the front section view of the separated member and the front view of the plane formed by it and the other five members. Based on this view, the cutting of the sleeve G corresponding to the separated member can be realized. It can be seen from the figure that the spliced ​​end of the sleeve G is composed of 4 cutting planes, which are the angle bisector plane a in the BB, CC, EE, and FF views. In the DD view, all the sleeves G are on one side of the cutting plane a, and no actual cutting is required. Read the relative torsion angles of the four views from the AA view, combined with the intersection point (O) of the center line of the member in the corresponding view and the direction angle of the angle bisector plane a, and the end face of the sleeve can be cut out by a cutting machine to realize cutting. This cutting method is universal and suitable for cutting all sleeves at this node.

[0024] , the method for drawing the cutting diagram of the above-mentioned sleeve (1) requires the assistance of the views of other sleeves (1) in the core component, and no matter whether the sleeve (1) is actually cut, it is necessary to print out the cross-sectional view before knowing it. Although it is intuitive and easy to understand, there is too much irrelevant information and it requires certain drawing reading experience to understand it. The following is a node matching theory, which can produce a method for drawing a sleeve cutting diagram only through the view of the sleeve (1). It is applicable to the cutting of the polyhedral pointed cone of the sleeve (1) at this node and should be regarded as an innovation.

[0025] , Attachment Figure 7 To separate the cutting drawing of the sleeve corresponding to the rod, the view is a front section view of the polyhedron cone side, including the projection lines of the 4 angle bisectors, the angles between adjacent projection lines (19.5°, 85.5°, 43.7°), and the angles between the angle bisectors and the center line of the sleeve (68.4°, 28.6°, 26.7°, 42.6°). This information combined with the sleeve length information can complete the cutting of the corresponding sleeve. Note: 1. The other 4 radius lines are the edge lines of the polyhedron cone, which are used to verify whether the style after cutting is consistent with the view. Figure 1 2. The direction of the center line of the casing points from the intersection side to the rod side, and the angle marking side is the angle side of the angle bisector. The angles are all acute angles and have no direction.

[0026] , the following combined with Figure 8, take the separated rod as an example to illustrate the innovative method of drawing the cutting drawing of this casing: 1. Draw section AA in the right side view of the casing to obtain the front section view of the polyhedron pointed cone side, and move its pointed cone point (O) to the extension line of the casing centerline; 2. Find the point marked with length DL, and draw a perpendicular line from this point to the casing centerline (this point is the intersection of the edge line and the outer contour line of the polyhedron pointed cone, the angle between the edge line at this point and the casing 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 of other edge lines with this perpendicular line (when the angle between the edge line and the casing centerline is an obtuse angle, it intersects with the extension line), and draw a line parallel to the casing centerline and the projection line of the edge line of the corresponding polyhedron pointed cone on the left (or the extension line of the projection line) 4. Connect the new points on the projection lines of the two adjacent edge lines, and draw a perpendicular line from point (O) to it. This perpendicular line is the projection line of the angle bisector in the angle bisector plane corresponding to the plane where the two edge lines are located, and its pointing side is the angle annotation side; 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 in step 4 (or the extension of the connecting line); 6. Connect point (O) and the new intersection point. 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 casing, and it is marked on the outside of the corresponding perpendicular line; 7. The angle between the four perpendicular lines is the angle between the adjacent projection lines; 8. Arrange the annotations and delete useless pixels. This completes a similar method to the attached figure. Figure 7 Cutting diagram of the sleeve corresponding to the separation rod.

[0027] This innovative method of drawing the cutting diagram of the casing is rigorous and has corresponding mathematical and theoretical proofs. Figure 8Specific explanation: 1. The second step of the previous paragraph is equivalent to obtaining a plane a determined by the vertical line and the normal of the right view; 2. The third step of the previous paragraph is equivalent to finding the intersection point between the edge line of the polyhedron cone (or the extension of the edge line) and plane a in three-dimensional space. The projection points of the intersection points found in the AA section view are 4 new points; 4. Because the center line of the casing is perpendicular to plane a, the center line of the casing is perpendicular to the line connecting the intersection points in plane a. Because the vertical line made in the fourth step of the previous paragraph is perpendicular to the line connecting the new points, and the AA plane is parallel to plane a, the vertical line made in the fourth step of the previous paragraph is also perpendicular to the line connecting the intersection points in plane a. The corresponding intersection line, so the intersection line in plane a is perpendicular to the plane b determined by the center line of the casing and the corresponding vertical line made in step 4 of the previous paragraph. Because the intersection line in plane a is on a plane c (or extended surface) of the polyhedral cone in three-dimensional space, plane b is perpendicular to the corresponding plane c; 5. Plane c is the required cutting surface (angle bisector surface), and plane b is the cutting view. In plane b, plane c is a straight line; 6. Steps 5 and 6 of the previous paragraph are to construct a right triangle in plane b in the AA section view, so as to obtain the angle between the angle bisector and the center line of the casing. This proof is rigorous, and 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 cutting drawings of all casings at this node.

[0028] The angle bisector plane splicing process of the multi-directional detachable equal-diameter circular tube plug-in node in the assembly includes the following steps: For the spatial multi-directional rod intersection node, whether it can be realized mainly depends on whether the assembly positioning work can be realized, regardless of whether this work is completed in the processing stage or the construction stage. The structure of the sleeve in this node has significant advantages in the assembly process, turning the most complex work into a simple work, which should be regarded as a technological breakthrough. The specific angle bisector surface splicing process is as follows: first read the part number of the sleeve from the core component assembly drawing, find the required sleeve after cutting, and the assembly drawing does not need dimension marking; then take the non-concave end of any one of the sleeves as the fixed end, and assume that the non-concave end of this sleeve contains x planes, each of which is obtained by cutting the angle bisector surface of the sleeve and another sleeve in the core component, so x sleeves connected to it can be found. According to the coincidence theorem of sleeve cutting surfaces, the corresponding cutting surfaces must be equal. Take any one of the x sleeves connected to it and try to splice it with the cutting surface of the fixed sleeve. There must be at least one plane that can completely coincide. , when more than one plane meets the requirements, the only corresponding splicing surface can be determined in combination with the core component assembly diagram, and spot welding can be performed along the outer contour of this splicing surface to complete the splicing of one sleeve. Similarly, the splicing of the remaining x-1 sleeves can be completed. At this time, the x+1 sleeves that have been fixed are used as the fixed ends, and the remaining unfixed sleeves corresponding to the external leakage planes of their non-concave body ends are continued to be found. The splicing is performed in the same way until all the sleeves belonging to the core component are spliced ​​to the fixed end. If the gap of a splicing surface is large, the gap can be averaged to other splicing surfaces through fine-tuning to achieve the purpose of reducing the error, and the assembly and positioning of the core component is completed. Because one angle bisector plane must correspond to two sleeves, and the splicing ends of the sleeves are cut along the angle bisector plane, the final core component will not have a leaking cutting surface and is closed.

[0029] The casing cutting surface coincidence theorem is shown in the attached Fig. 9 The proof is as follows: Because the wall thickness and diameter of the casing are consistent, and the center lines intersect at one point (O), it can be proved that the walls of any two casings on the cutting (joining) surface coincide. Fig. 9The view is the OAB plane, OA is the centerline of the right tube, OB is the centerline of the left tube, OC is the OA and OB angle bisectors, and the CC section is the corresponding cutting surface of the two tubes. Let point P be any point in the corresponding cutting surface of the right tube, which satisfies the distance to OA ≥ rt, d ≤ r, r is the radius of the casing, and t is the wall thickness of the casing. According to the angle bisector theorem, the distance from point P' projected to the OAB plane from point P to the OA and OB lines is equal. According to the Pythagorean theorem, the distance from point P to OB is also = d. Therefore, it can be seen that point P is also on the corresponding cutting surface of the left tube. Conversely, it can be proved that any point in the left tube is also in the right tube. Therefore, any cutting surface will not produce misalignment, opening or collision, and the corresponding cutting surfaces of the left and right tubes coincide, that is, they are equal.

[0030] The above-mentioned angle-bisector plane splicing process is not only applicable to manual splicing, but also to fully automatic splicing by robotic arms, and the steps are the same. Difference 1 is that the robotic arm can achieve a low error effect without fine-tuning, and difference 2 is that manual labor needs to obtain information from the assembly drawing, while the robotic arm can also obtain information directly from the model, omitting the drawing work. Subsequent welding operations can be performed by either manual tools or fully automatic welding robots.

[0031] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with specific implementation steps and with reference to the accompanying drawings.

[0032] First, select the structure. Because this node supports the node construction of the intersection of equal-diameter rods of any number (2~n) in three-dimensional space and any spatial angle except coincidence, there is no restriction on the shape. Existing three-dimensional modeling software (CAD, Rhino, SketchUp, Tekla, 3D3S, etc.) can be used for configuration design to determine the grid structure. Then, according to the project requirements and common market material specifications, the outer diameter and wall thickness of the rods and casings are preliminarily selected. When the safety of the structure needs to be verified, it is verified according to the following method.

[0033] When selecting a structure, it is required that all rods that meet at the same node have the same outer diameter. The middle of the rod can be reduced in diameter. Breaking one rod into two newly added reduced diameter nodes is considered a rigid connection (reduced diameter nodes are existing technologies, and finished tapered tubes can be purchased or stamped using molds). Because the structural load within the applicable range of this node is small, the cross-section of the rod selected based on the appearance size requirements is often large enough. In the case of similar structural entity verification, the cross-section can be determined directly without force analysis. When the structural configuration is relatively novel or the load is large and you want to determine the optimal cross-section, the spatial grid structure of this node is used. The force analysis can be performed using existing structural calculation software (3D3S, etc.) according to the conventional spatial grid structure. The rigid connection and hinged assumption of the rod is specified according to the requirements of the industry specification according to different structural types and grid arrangements. The rod must meet the requirements of the steel structure design standard GB50017-2017 on the slenderness ratio and diameter-thickness ratio of the steel pipe. The stress ratio control value is determined according to the secondary pipe bearing capacity / f (main pipe tensile and compressive strength) in the corresponding prior art 1 in this specification. The maximum steel pipe section in the node calculated in this way is used as the minimum section of the casing in the node. For the structure within the applicable range of this node, it can be regarded as only the secondary pipe but no main pipe. Now let's take an example to illustrate. For example, for the case where the formula of Article 13.3.2-1 of the specification is applicable, when the sections of the primary and secondary pipes are the same, the minimum stress ratio of the main pipes on both sides of the node is set as minσ / fy=0.092, the angle θ=90°, and the casing wall thickness t=1mm. The secondary pipe bearing capacity design value Ncx=27.82f is calculated. When the casing diameter R=25mm is estimated, the secondary pipe bearing capacity stress ratio=0.0922, which is independent of the material f. For this case, 0.09 can be taken as the maximum value of the estimated casing stress ratio.

[0034] Then, after the rod tube wall thickness is reduced and the material and Poisson's ratio are adjusted, the stress analysis is performed again. The rod stress ratio is controlled within 0.5 to determine the rod specifications. When the rod is made of steel, the requirements for the steel pipe diameter-thickness ratio in the specification must be met. Then, based on the maximum internal force under the combined working condition of the rod at this time, the minimum contact area A of the rod structure adhesive layer can be determined, and the minimum reduced diameter tube length L1 can be further calculated.

[0035] At this point, the preliminary selection is completed. Because for most spatial grid structures, both the existing technology 1 and this node are beyond the scope of application of the specification, it is necessary to verify the structural bearing capacity through simulated load experiments. Because the scope of application of this node determines that its structural dimensions are small and the structural load is small, a simulated load of ≥1.5 times the calculated load can be directly applied to the physical structure to verify the safety of the structure.

[0036] Explanation on the importance of experimental inspection: Because the secondary rod capacity calculated in the specification is estimated based on the main rod, the main rod cutting will definitely affect the secondary rod capacity, so the secondary rod capacity calculated using the specification is too large for the casing of this node, and it still cannot replace experimental inspection. The finite element analysis software in the existing technology can be used to calculate the force of this node, but because the stiffness of this node is different from the stiffness of the existing technology type 1 node in the specification, the internal force value of the rod calculated by the force analysis software may not be accurate enough. When used for finite element analysis, a certain magnification factor needs to be considered. As a reference for typical nodes, experimental verification is still the standard. This is the conventional verification method for the applicable field of this node.

[0037] (2) Then the modeling, detailed drawing and material extraction of the members and nodes are carried out. The industry term is detailed drawing deepening design work. This is a time-consuming and labor-intensive process. A good node type should have the principle of universality, be supported by mathematical theory, and be able to ensure the consistency of the node. The deepening node style should not be different due to the different understandings of the technicians in the field. It should also have certain efficiency advantages. This node is a node type with these advantages. The node type of the traditional existing technology 1 generally needs to be analyzed specifically for different intersection situations. It is necessary to distinguish between the primary and secondary members, which members need to be connected and which do not need to be connected. The secondary trunks should also be distinguished according to the different forces and cross-sections, which one is not cut below and which one is cut on the intersection line above. This is a very time-consuming work that requires the support of multiple process data. The splicing surface cutting of the sleeve of this node has the principle of universality: each sleeve in the core component is cut with other sleeves along the corresponding sleeve angle bisector plane, and the cutting depth and order are not restricted. It is described in detail in S1, which can greatly improve the efficiency of node deepening and ensure the consistency of deepening nodes. During the deepening process, the relevant structural requirements of the above-mentioned casing, plug-in structure and structural adhesive layer also need to be met.

[0038] (3) Then the structure is processed. This includes material procurement, cutting, assembly, welding, shrinking, painting, packaging, etc., which are the manufacturing links of the product. There are two main difficulties. The first is the cutting of the casing, which is described in detail in S2, and the second is the assembly of the core components, which is described in detail in S3. The rest can be achieved by existing technologies.

[0039] (4) Then the structure is constructed. This includes transportation, installation, acceptance, etc., and is the application link of the product. The plug-in structure has its advantages and disadvantages. The disadvantage is that because the necked tubes at both ends of the rod need to be inserted into the corresponding sleeves, during installation, it is necessary to classify the rods in the structure by length according to the overall scaling mode disclosed in the invention content and the minimum L calculation formula that does not affect the installation, determine the installation order, and then install them in sequence. The advantages are: traditional welding connections are difficult to locate, the welding area needs to be polished and repainted, and the construction is difficult; traditional bolt connections are mostly suitable for hinged or planar structures, and the torsion angle matching of the rods needs to be considered. The support for spatial grid structures is limited, and when high-strength bolts are selected, the contact surface is not painted, and repainting is required after connection, which is difficult to construct; traditional threaded connections are not suitable for spatial grid structures. Comparative analysis shows that the node of this application has the advantages of connection without damaging the skin, no need to consider the torsion angle of the rod, simple operation steps, extremely low installation tools and equipment requirements, and extremely low requirements for the node's rigidity and angle assembly frame. The necking at both ends of the rod is convenient for both connection and determination of the rod length, and is easy to install.

[0040] (5) Finally, support disassembly when disassembly is required. Structural adhesives are widely used in the bonding of metals, ceramics, plastics, rubber, wood and other materials, and can partially replace traditional connection forms such as welding, riveting, and bolting. This node is an innovation in its application scope. It provides the node with bearing capacity support, airtightness support, cold connection anti-skin damage support, and detachable support, and is a necessary component unit for node connection.

[0041] This is a specific implementation step of a spatial grid structure using the nodes of this application, which not only includes a complete structural construction process, but also includes unique theoretical support. It is a complete and innovative invention.

[0042] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

[0043] Embodiment 1: The nodes are easy to install and remove. Fig.11It is a membrane structure tent, with a single-layer lattice shell structure using the node of this application on the outside and a membrane structure on the inside. The number of supports = 60, the number of supports = 10, and when other rods are regarded as closed curved lattice shell structures, the number of edges E = 175, the number of vertices V = 67, and according to the Euler formula, the number of faces F = 2 + EV = 110 (including the bottom surface and the door). When installing, first install the single-layer lattice shell, and the plug-in structure is fastened with structural glue. After 24 hours, the membrane structure is installed from the inside after the strength of the structural glue reaches the standard. The tensioning node of the membrane structure is fastened with bolts and the additional nuts in the inner sleeve of the core component of the corresponding application node. The membrane structure applies centripetal force to the outer single-layer lattice shell structure, which can improve the overall bearing capacity of the structure. The combined structure has reasonable force, large internal space, strong wind and snow resistance, easy installation, and the nodes are all detachable, which is easy to disassemble, light weight, easy to carry, and reusable.

[0044] Embodiment 2: The node does not limit the number and angle of equal diameter steel pipes, and is easy to transport, such as attached Fig.12 It is a polyhedral outline sculpture of a bear, which belongs to a closed curved lattice shell structure. Its edge number E = 868, the number of vertices V = 298, and according to the Euler formula, the number of faces F = 2 + EV = 572. There are many node combination styles, among which the least node contains 3 rods, and the most node contains 12 rods. It is 6.12m long, 2.9m wide, and 3.75m high. The casing specification is φ25*1.5 stainless steel pipe, the rod specification is φ25*1 stainless steel pipe, the longest node spacing is 1.68m, and the turning radius is 0.84cm. The calculated rod slenderness ratio is 168 / 0.84=200, which meets the requirements of the specification. The ratio of the outer diameter of the steel pipe to the wall thickness is 50<100εk²=113.7, which meets the requirements of the specification. Because the stress of the rod is relatively small, it only needs to meet the structural requirements. The length of some rods is too short, and one end of the rod is merged with the corresponding casing, and the other side is normally made into a reduced diameter pipe structure and plugged into the corresponding casing. Its delivery volume is within 1.5 square meters and its weight is within 320KG. If the overall transportation mode is adopted, the volume of the external rectangular block after assembly is 66.6 square meters, and the width and height are both over the limit, so it needs to be transported in blocks, which has high transportation costs. The delivery mode of easy-to-install rods + core components can significantly reduce transportation costs.

[0045] Embodiment 3: The node supports unconventional spatial grids and rigid connections. Whether it is embodiment 1, embodiment 2, or a single-layer grid, double-layer grid, three-dimensional truss, etc., the rods connected to it can form a plane ring, and no other rods will pass through the ring, which is referred to as a plane ring grid. This type of grid can use panels to replace rods. For example, embodiment 2 has a corresponding polyhedron sculpture. But similar to the attached design of the applicant Fig.13The round square table, except for the two plane rings on the top and bottom, has no other rods that can form plane rings. The rod structure cannot be replaced by panels. It is a unique structure type of rods. The number of edges E = 20 and the number of vertices V = 12 of the round square table support structure. This structure requires at least some of the rods to be rigidly connected to form a geometric invariant. This node can be regarded as a rigid connection under low loads, and can transmit shear force, axial force, bending moment and torque. It is an ideal node for similar structures.

[0046] Example 4: Self-supporting pipe transportation or pipeline structure.

[0047] The airtightness advantages of the hollow structure inside the node and the hollow structure and plug-in structure make the structure composed of the nodes have the characteristics of internal connection and closure. It is suitable for pipeline transportation under low internal and external pressure difference or as a waterproof pipeline for lines, and has a certain self-bearing capacity. Fig.14 It is a space-time channel project (colorful light decoration structure) with a radius of 9.5m and an arch height of 3.96m. The rods are made of φ32*2mm colored translucent PC hard tubes, and the casing is made of 1.5mm thick stainless steel tubes. A light strip is set inside, which has the advantages of being waterproof, beautiful and self-supporting.

[0048] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims.

[0049] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A multi-directional detachable equal-diameter circular tube plug-in node based on angle-bisector cutting, the node is the key part that connects the bars at the intersection, characterized in that The node comprises more than two rods (2) and sleeves (1) corresponding to the rods (2), the correspondence means that the center lines are in line and the outer diameters are the same, the rods (2) and the corresponding sleeves (1) are connected via 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 a whole at the intersection, and the intersection means that the center lines of the sleeves (1) are aligned. The intersection point (O) is the intersection point. The intersection end of the sleeve (1) is a polyhedral cone. The polyhedral cone is formed by cutting the intersection end of the sleeve with other sleeves in the node along the corresponding sleeve angle bisector plane when the intersection end of the sleeve is regarded as solid and infinitely extended. The point (O) is the vertex. When the polyhedral cone is composed of two planes, the point (O) is the midpoint of the intersection line. The angle bisector plane is the plane where the two intersecting straight lines of the angle bisector corresponding to the center lines of the two sleeves and the normal of the plane determined by the center lines of the two sleeves are located. The outer surface contour line of the polyhedral pointed cone has a weld, and the weld connects the sleeves in the node into a whole, which is the core component of the node. The sleeves connected by the weld are closed, and the closure means that there is no misalignment, opening or collision in the tube wall, and the inner and outer surfaces are closed. The rod (2) is a hard round tube with the same outer diameter and has a certain plasticity. The end of the necking tube (3) is flush at the diameter change point, and the end of the necking 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 a uniform wall thickness and the tensile and compressive strength of the cross section of the sleeve is not less than the maximum tensile and compressive strength of the cross 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 plug-in length of the rod reducer (3).

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

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

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

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