Bolt-free integral dropper crimping pipe crimping forming simulation method
Through finite element simulation, the bolt-free overall crimping process is simulated, which solves the problem of uneven loading effects in the traditional crimping process, improves the simulation convergence, and provides a foundation for subsequent crimping performance simulation and life prediction.
Patent Information
- Application Number
- CN202411905608.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-04-01
AI Technical Summary
In the traditional hanging string crimping process, the loading effect of the crimping mold is uneven, resulting in uneven force under the model, increasing the convergence difficulty of finite element simulation calculation, and affecting the processing accuracy of parts.
The crimping forming simulation method of bolt-free integral hanging string crimping pipe is used to simulate the crimping process through finite element simulation methods, and a new crimping method is introduced to alleviate the convergence difficulties during the simulation process, and provide a foundation for subsequent simulation of wear, slip and pull-off phenomena.
The convergence of the crimping process of the contact net bolt-free overall hanging string crimping pipe in finite element simulation is improved, and the relevant simulation help is provided for the slippage, pull-off and other phenomena of the crimping string under the action of external loads, and provides a foundation for the wear simulation of the crimping pipe.
Smart Images
Figure CN119740438A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of suspension string twisted wire crimping, and in particular relates to a crimping forming simulation method for a bolt-free integral suspension string crimping tube. Background Art
[0002] With the rapid development of rail transit in my country, contact network parts are constantly updated, and the crimping method of the suspension string strands has also changed accordingly. Since the two ends of the overall suspension string contain crimping structures, their function is to combine the suspension string strands and the heart-shaped rings into a whole by crimping. The effect of crimping will directly affect the performance and service life of the suspension string. During the crimping process, both the crimping tube and the suspension string strands will produce plastic deformation, and the change in the model structure will cause the mechanical properties of the suspension string strands to change, which will affect the subsequent simulation analysis of the overall suspension string performance and its life prediction analysis. Therefore, the crimping process should be simulated first, the plastic deformation generated during the crimping process should be simulated, and the crimped model should be obtained before other subsequent simulation work to improve the accuracy and reliability of the simulation results of the suspension string.
[0003] like Figure 1 As shown in the figure, the traditional crimping process usually adopts the crimping method of squeezing the crimping dies on both sides toward the middle. Since the load applied to the crimping dies needs to act on the rectangular outer surfaces on both sides of the dies, and the crimping structure in this crimping method is relatively complex, and the internal features include inclined surfaces, it may cause uneven force on the model. At the same time, during the process of the die extruding and crimping the tube, there is a certain gap between the two dies, which may cause large deformation of the model. These problems will not only increase the convergence difficulty of the finite element simulation calculation, but also affect the machining accuracy of the parts in actual production. Summary of the invention
[0004] The present invention provides a simulation method for crimping forming of a boltless integral suspension string crimping tube, which aims to simulate the crimping forming process of the integral suspension string crimping tube of the contact network by means of finite element simulation. By introducing a new crimping method in the simulation program, the problem of convergence difficulty in the simulation process is effectively alleviated, and a basis is provided for the simulation of phenomena such as wear, slippage and pull-off of the integral suspension string, thereby providing guiding suggestions for the operation and maintenance of the railway contact network.
[0005] The technical solution adopted by the present invention is as follows:
[0006] A simulation method for crimping and forming a boltless integral suspension string crimping tube comprises the following steps:
[0007] S1: Conduct 3D modeling of the crimping tube and crimping die, and import the constructed 3D model into an assembly model and then import it into the finite element analysis software;
[0008] S2: Assign relevant attributes to the assembly model in the finite element analysis software, define the contact pairs and connection pairs in the assembly model, and perform meshing on the assembly model;
[0009] S3: Apply load to the assembly model to simulate the plastic deformation of the compression tube caused by external load;
[0010] S4: Obtain the plastic deformation and equivalent stress distribution of each part of the compression tube, and inversely calculate the support reaction force required for the compression of each part of the compression tube.
[0011] Preferably, since the crimping part of the crimping tube is composed of a cylinder and two regular hexagonal prisms respectively connected to the two ends of the cylinder, the crimping mold is arranged to be composed of six completely identical crimping parts, and the contact surface shape of each crimping part matches the shape of one side of the crimping tube, so that the six crimping parts are respectively fitted with the six surfaces of the crimping tube.
[0012] Preferably, during assembly in S1, the end face of one end of the suspension string strand and the upper end of the crimping tube are matched to the same horizontal plane, and the center strand of the suspension string strand is concentric with the crimping tube; the two ends of the crimping mold and the two ends of the crimping tube are matched to the same horizontal plane.
[0013] Preferably, in S3, the dimensions of the actual crimped tube part sample are measured, and the displacement of each crimping die in each degree of freedom is calculated according to the geometric structure, trigonometric function and the Pythagorean theorem, and a remote displacement load perpendicular to the surface is applied to the outer surfaces of the six crimped parts according to the calculation results.
[0014] Preferably, since there is no requirement for axial plastic deformation of the initial crimping tube, the applied displacement load only produces an effect in the plane formed by the x-axis and the y-axis.
[0015] Preferably, the remote displacement load is applied uniformly in all load steps of the simulation analysis calculation process and reaches a maximum value at the end.
[0016] Preferably, the specific process of defining the contact pairs and connection pairs in the assembly model in S2 is:
[0017] A: The inner surfaces of the six crimping parts and the outer surface of the crimping tube are set as contact pairs respectively, where the outer surface of the crimping tube is defined as the contact surface and the inner surface of the crimping die is defined as the target surface. The six groups of contact pairs are defined as friction contacts, and the friction coefficient is set according to the material of the contact pairs;
[0018] B: The side surface of the suspension wire and the inner surface of the crimping tube are set as a contact pair, where the surface of the suspension wire is set as the contact surface and the inner surface of the crimping die is set as the target surface. The contact pair is defined as friction contact, and the friction coefficient is set according to the material of the contact pair.
[0019] C: Apply a geometry-ground connection pair to the upper end face of the crimping tube, and set the connection mode to fixed.
[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0021] The method of the present invention enhances the convergence of the crimping process of the contact network boltless integral suspension string crimping tube in the finite element simulation by introducing the structure and crimping method of the crimping die into the simulation program. The present invention can provide certain help for the simulation analysis of the slippage, pull-off and other phenomena of the suspension string after crimping under the action of external loads, and can also be used as a basic model for the wear simulation of the crimping tube. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a structural schematic diagram of the traditional hanging string crimping method in the prior art.
[0023] Figure 2 Schematic diagram of the structure of the overall suspension string compression pipe part of the contact network in the example of the present invention, wherein Figure 2 (a) is a three-dimensional model diagram of the overall suspension string compression pipe part of the overhead contact network; Figure 2 (b) is a physical picture of the overall suspension string compression pipe part of the contact network.
[0024] Figure 3 It is a schematic structural diagram of the crimping die in an example of the present invention.
[0025] Figure 4 It is a material property diagram of plastic deformation of copper alloy given in the example of the present invention (i.e., a relationship diagram between plastic strain and stress).
[0026] Figure 5 This is a graph showing the change in friction coefficient of the copper alloy at the initial stage of running-in in the example of the present invention.
[0027] Figure 6 It is a schematic diagram of the position of the connection pair applied to the crimping tube in an example of the present invention.
[0028] Figure 7 (a) and (b) are schematic diagrams of the application method of remote displacement load based on Ansys mechanical field simulation in an example of the present invention.
[0029] Figure 8 It is a schematic diagram of a method for calculating the x-axis and y-axis components of a remote displacement load in an example of the present invention.
[0030] Fig. 9 (a), (b), (c), and (d) are respectively cloud diagrams of the total deformation result of the crimped tube, cloud diagrams of the equivalent stress result of the crimped tube, cloud diagrams of the total deformation result of the suspension string strands, and cloud diagrams of the equivalent stress result of the suspension string strands in an example of the present invention based on Ansys mechanical field simulation. DETAILED DESCRIPTION
[0031] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.
[0032] In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or are the positions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.
[0033] A simulation method for crimping forming of boltless integral suspension string crimping tube, which is based on ANSYS mechanical field simulation:
[0034] S1: According to the actual measured size of the overall suspension string crimping tube, the initial crimping tube, suspension string strand and external crimping structure are three-dimensionally modeled, and the models are assembled into an assembly. Since the heart-shaped ring at the upper end of the crimping tube has little effect on the relevant content of this article, the initial crimping tube is simplified to a hollow cylindrical structure in the middle, where the inner diameter of the crimping tube is 5.4mm, the outer diameter is 10mm, and the length is 40mm. Since the structure of the 7x7 suspension string strand is too complicated, it increases the calculation amount and convergence difficulty in the finite element simulation calculation, so it is simplified to a 1x7 suspension string strand model with a length of 100mm. During assembly, the end face of one end of the suspension string strand is matched with the upper end of the initial crimping tube to the same horizontal plane, and the center strand of the suspension string strand is concentric with the initial crimping tube; the inner convex surfaces of the six crimping dies are set to be tangent to the outer surface of the crimping tube, and the two ends of the crimping dies are matched with the two ends of the initial crimping tube to the same horizontal plane.
[0035] S2: Build a static dynamics module in Ansys Workbench and import the 3D model into the module. Referring to the materials of parts in actual production, the crimping tube and the suspension string strand are both made of copper alloy. Therefore, the plastic deformation properties of the copper alloy material are given in the engineering data in Ansys, that is, the relationship between plastic strain and stress. The corresponding relationship is as follows: Figure 4 , as shown in Table 1.
[0036] Table 1 Plastic strain and stress table
[0037]
[0038] S3: Change the model stiffness behavior of the crimping tube and the dropper strand to flexible, and the material to copper alloy; change the model stiffness behavior of the external crimping structure to rigid, and the material to structural steel, and define the model contact and connection pairs:
[0039] A: Set the inner surfaces of the six crimping dies and the outer surface of the crimping tube as contact pairs, where the outer surface of the crimping tube is defined as the contact surface and the inner surface of the crimping dies is defined as the target surface. Define the six contact pairs as friction contacts. Figure 5 It can be seen that the friction coefficient of the copper alloy in the initial stage of running-in is concentrated between 0.13 and 0.16, so the friction coefficient of the copper alloy is taken as 0.15 for simulation calculation.
[0040] B: Set the side surface of the suspension wire and the inner surface of the crimping tube as the contact pair, where the surface of the suspension wire is set as the contact surface and the inner surface of the crimping die is set as the target surface. Define all contact pairs as friction contacts. Since the crimping process can be completed in a short time, the friction coefficient value is taken as reference to the initial running-in period of copper alloy. Figure 5 It can be seen that the friction coefficient of the copper alloy in the initial stage of running-in is concentrated between 0.13 and 0.16, so the friction coefficient of the copper alloy is taken as 0.15 for simulation calculation.
[0041] C: Figure 6 As shown, a geometry-ground connection pair is applied to the upper end face of the initial compression tube, and the connection mode is set to fixed.
[0042] Add size adjustment in the mesh setting, use the "automatic division" in Ansys to divide the inner surface of the crimping die, the crimping tube and the suspension wire into meshes, and obtain the crimping process part model after mesh division. The mesh size of the inner surface of the crimping die is set to 1mm, the mesh size of the initial crimping tube is set to 1mm, and the mesh size of the suspension wire is set to 0.5mm.
[0043] S3: In the simulation analysis setting, a remote displacement perpendicular to the surface is applied to the outer surface of the six crimping structures, as shown in Figure 7(a). The dimensions of the actual crimping tube part sample are measured, and the displacement of each crimping die in each degree of freedom is calculated based on the geometric structure, trigonometric functions and the Pythagorean theorem. Since this crimping method does not require axial plastic deformation of the initial crimping tube, the applied displacement load only has an effect on the plane formed by the x-axis and y-axis. Figure 7 As shown in (b), the model is simplified and relevant calculations are performed in a two-dimensional plane. Among them, the remote displacement and remote displacement 4 are parallel to the y-axis, so the remote displacement load can be directly applied according to the measured crimping depth. For the remaining 4 remote displacement loads, since the load action direction is not parallel to the coordinate axis, the displacement components of each displacement load on the x-axis and y-axis must be calculated separately to achieve the expected crimping effect. According to the definition method of Ansys remote displacement load, Figure 7 In (b), A, B, C, D, E, and F correspond to the midpoints of their edges. In the xy plane, the directions of the six remote displacement loads are perpendicular to the outer edge of the crimping die and point to the center of the crimping tube. The structure contained in the crimping tube is a regular hexagon. Figure 7 (b) Simplify again as Figure 8 As shown. Taking point C as an example, calculate the displacement components of remote displacement 3 on the x-axis and y-axis. Figure 8 As shown in the figure, the three diagonals of the regular hexagon intersect at its center point, so the regular hexagon is split into six equilateral triangles. The action point of remote displacement 3 is equivalent to point C, and the direction is perpendicular to the side line and points to the center point of the hexagon, so the line connecting point C and the center point of the hexagon is perpendicular to the side line. According to the properties of the equilateral triangle, ∠1 and ∠2 are both 30°. At point C, the remote displacement load 3 is split along the x-axis and y-axis, and a triangle is constructed. According to the geometric relationship, the vertical direction is the y-axis displacement component, the horizontal direction is the x-axis displacement component, the hypotenuse is the remote displacement 3, and ∠3 is 30°. Since the size of remote displacement 3 is 0.75mm, according to trigonometric functions and the Pythagorean theorem, it can be calculated that the displacement component of the x-axis is approximately 0.6495mm, and the direction is along the positive direction of the x-axis; the displacement component of the y-axis is 0.375mm, and the direction is along the negative direction of the y-axis. The splitting calculation method of the remaining remote displacements is the same. After calculation, the data of each remote displacement are shown in Table 2. The remote displacement load is applied evenly throughout all load steps in the simulation analysis and reaches its maximum value at the end.
[0044] Table 2 Remote displacement data table
[0045]
[0046] S4: Analyze the results and obtain the total deformation of the plastic deformation generated during the crimping process and the equivalent stress result cloud map (add the "Total Deformation", "Equivalent Stress", and "Force Response" probes in the "Solve" module of Ansys, and retrieve all the calculation results to obtain the simulation result cloud map), such as Fig. 9 The results of the analysis and calculation are processed, and probes are added to the surfaces of the six external crimping structures where the remote displacement is applied. The force reaction during the crimping process is calculated, and the support reaction force required to form the crimping tube can be inversely calculated. The support reaction forces corresponding to the six external crimping structures are shown in Table 3.
[0047] Table 3 Support reaction forces corresponding to six external crimping structures
[0048]
[0049] Reference Fig. 9 From the simulation result cloud diagram and Table 3, the support and reaction forces of each external crimping die are approximated according to the order of magnitude and can be considered equal, so the external load on the crimping tube can be approximately balanced. In addition, the simulated total deformation cloud diagram does not have large deformation and structural distortion, and the simulated equivalent stress result cloud diagram does not have stress singularity. Through the measurement of actual parts, the depth of the crimping part of the crimping tube is about 0.75mm. Fig. 9 From the simulation result cloud chart, we can see that the depth at the same position is about 0.76mm, the difference between the two is 0.01mm, and the error is 1.3%. Therefore, this crimping method can realize the crimping forming of the crimping tube and the crimping tube morphology formed by this method is the same as the actual part morphology. Within the allowable error range, the size of the crimping tube formed by this crimping method is consistent with the actual part.
[0050] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.
Claims
1. A simulation method for crimping and forming a boltless integral suspension string crimping tube, characterized in that: The following steps are involved: S1: Conduct 3D modeling of the crimping tube and crimping die, and import the constructed 3D model into an assembly model and then import it into the finite element analysis software; S2: Assign relevant attributes to the assembly model in the finite element analysis software, define the contact pairs and connection pairs in the assembly model, and perform meshing on the assembly model; S3: Apply load to the assembly model to simulate the plastic deformation of the compression tube caused by external load; S4: Obtain the plastic deformation and equivalent stress distribution of each part of the compression tube, and inversely calculate the support reaction force required for the compression of each part of the compression tube.
2. The method for simulating crimping forming of a boltless integral suspension string crimping tube according to claim 1, characterized in that: The crimping die is composed of six identical crimping parts, and the contact surface shape of each crimping part matches the shape of one side of the crimping tube, so that the six crimping parts are respectively fitted with the six surfaces of the crimping tube.
3. The method for simulating crimping forming of a boltless integral suspension string crimping tube according to claim 2, characterized in that: During assembly in S1, the end face of one end of the suspension string strand and the upper end of the crimping tube are matched to the same horizontal plane, and the center strand of the suspension string strand is concentric with the crimping tube; the two ends of the crimping mold and the two ends of the crimping tube are matched to the same horizontal plane.
4. The method for simulating crimping forming of a boltless integral suspension string crimping tube according to claim 2, characterized in that: In S3, the dimensions of the actual crimped tube part sample are measured, and the displacement of each crimping die in each degree of freedom is calculated according to the geometric structure, trigonometric function and the Pythagorean theorem. According to the calculation results, a remote displacement load perpendicular to the surface is applied to the outer surfaces of the six crimped parts.
5. The method for simulating crimping forming of a boltless integral suspension string crimping tube according to claim 4, characterized in that: The remote displacement load is applied evenly throughout all load steps in the simulation analysis and reaches its maximum value at the end.
6. The method for simulating crimping forming of a boltless integral suspension string crimping tube according to claim 2, characterized in that: The specific process of defining contact pairs and connection pairs in the assembly model in S2 is: A: The inner surfaces of the six crimping parts and the outer surface of the crimping tube are set as contact pairs respectively, where the outer surface of the crimping tube is defined as the contact surface and the inner surface of the crimping die is defined as the target surface. The six groups of contact pairs are defined as friction contacts, and the friction coefficient is set according to the material of the contact pairs; B: The side surface of the suspension wire and the inner surface of the crimping tube are set as a contact pair, where the surface of the suspension wire is set as the contact surface and the inner surface of the crimping die is set as the target surface. The contact pair is defined as friction contact, and the friction coefficient is set according to the material of the contact pair. C: Apply a geometry-ground connection pair to the upper end face of the crimping tube, and set the connection mode to fixed.