Nail plate weaving type metal rubber forming simulation method

Abstract

The invention provides a nail plate weaving type metal rubber forming simulation method, and belongs to the technical field of porous metal rubber material processing. A spiral metal wire path conforming to an actual weaving process is constructed by utilizing a light reflection law and considering a positioning nail; a curved surface parameterization mapping algorithm is applied, a plane weaving path is converted into a three-dimensional spiral baseline parameter equation according to a rolled or folded blank manufacturing process, a mathematical model of a continuous metal wire spiral coil is constructed through spatial transformation, and an initial blank structure with process authenticity is generated. In the forming simulation stage, the model is imported into finite element software, numerical simulation of the cold stamping forming process is achieved in combination with quasi-static extrusion and a dynamic explicit algorithm, and the metal rubber mesoscopic finite element model is obtained. According to the method, on the basis of a real weaving process and a blank rolling or folding process, the three-dimensional winding track of the metal wire can be continuously and accurately reconstructed, and the obtained model can accurately represent the structural characteristics of metal rubber.

Description

Technical Field

[0001] The invention belongs to the technical field of porous metal rubber material processing, and particularly relates to a nail plate braided metal rubber molding simulation method. Background Art

[0002] Metal rubber, a new type of elastic porous material, is manufactured using highly elastic fine metal wire as raw material. Through spiral forming, stretching, winding and laying, compression molding, and subsequent processing, it ultimately forms a three-dimensional mesh topology. In addition to its excellent vibration damping and isolation properties, metal rubber overcomes the limitations of traditional rubber materials in terms of aging resistance, long-term creep, hardening, and corrosion resistance. It is widely used in key areas such as vibration reduction in large industrial equipment and support systems for aerospace engines.

[0003] When subjected to load, the metal rubber exhibits elasticity and energy dissipation through the elastic deformation and dry friction of the contact between the internal metal coils. Current simulation studies of metal rubber mostly use phenomenological structural models, in which the physical meaning of the parameters is unclear, making it difficult to accurately characterize the mechanical response characteristics of the microstructure of the metal coils inside the metal rubber. Although the existing technology has proposed a modeling method based on the winding process, this method has difficulty in accurately constructing the blank structure formed by the nail plate weaving process; and the blank discretization iterative splicing strategy used has significant deviations from the actual continuous weaving process. Therefore, there is an urgent need to develop a simulation method for the formation of nail plate weaving metal rubber to more accurately characterize the three-dimensional winding trajectory and contact state of the metal wire of the nail plate weaving metal rubber, and provide a reliable theoretical model for material performance prediction and structural optimization. Summary of the Invention

[0004] The purpose of the present invention is to provide a nail-plate woven metal rubber molding simulation method, which generates a metal wire trajectory based on the real weaving process path to meet the requirements of continuous modeling, and forms a blank structure based on a rolling or folding process. It can effectively solve the above-mentioned problems and realize the full-scale modeling of metal rubber from the blank structure to the microscopic three-dimensional model.

[0005] The technical solution adopted by the present invention to achieve the purpose is: a braided metal rubber molding simulation method, comprising the following steps:

[0006] Step 1: Based on the law of light reflection, an algorithm for generating the spiral wire braiding path is constructed to ensure that the generated path is consistent with the actual braiding process path of the nail plate. The curvature of the generated path is adjusted according to the position of the positioning pins to ensure a continuous and smooth transition of the path. This establishes the braiding path of the spiral wire on the nail plate and its parameterized equation, thereby obtaining the baseline trajectory of the spiral wire within the nail plate braiding plane.

[0007] Step 2: Based on the blank rolling or folding process, a surface mapping algorithm is used to perform a three-dimensional spatial mapping reconstruction of the spiral wire's planar baseline trajectory to ensure that the spatial winding angle and pitch distribution of the baseline before and after the transformation remain unchanged, while ensuring the consistency of the blank preparation method with the actual process. The two-dimensional planar path of the spiral wire is converted into a three-dimensional spiral baseline to obtain a three-dimensional baseline equation. The rolling process is used for simulating cylindrical or toroidal metal rubber parts, and the folding process is used for simulating square metal rubber parts. The rolling or folding is performed along the length direction of the nail plate.

[0008] Step 3: Use spatial transformation along the three-dimensional baseline to construct the metal wire spiral structure and reconstruct the spatial topological relationship of the spiral turns, thereby obtaining the parameterized equation of the spiral metal wire and the initial blank model;

[0009] Step 4: Import the initial blank model into the finite element software and perform forming simulation in two steps using the explicit dynamics solver. First, quasi-statically extrude the initial blank model to obtain a blank structure with embedded metal wires. Then, a dynamic explicit algorithm is used to simulate the cold stamping process to obtain a metal-rubber microscopic finite element model.

[0010] Furthermore, step 1 includes the following steps:

[0011] Step 101: Determine the total length L of the braiding path, the angle α between the braiding path and the length direction of the nail plate, and the radius R of the positioning nail based on the metal rubber preparation parameters and the braiding process. p , the effective width H and effective length W of the nail plate;

[0012] Step 102: With the effective width H and effective length W of the nail board as the sides, construct a rectangular area as the effective area of the nail board. The sides of the rectangle are the boundaries of the nail board, the length direction is the X axis, the width direction is the Z axis, and the lower left corner is point O. Establish the XOZ coordinate system. Assume that the light enters from point O. The direction vector of the initial incident direction is:

[0013] v=(v x ,v z )=(cosα,sinα)

[0014] Where v x and v z are the components of the light direction vector on the X-axis and Z-axis respectively; taking the nail plate boundary as the reflective mirror, the straight line segment of the weaving path is constructed through the path trajectory formed by the reflection phenomenon of the light in the closed rectangular space, thereby obtaining the parametric equation of the straight line segment of the weaving path:

[0015] x0(t)=x i ±v x t, z0(t)=z i±v z t, t∈[t si ,t ei ]

[0016] Where x i 、z i represents the intersection of the light and the boundary of the nail plate at the i-th reflection, ± represents the change in the direction of the light as the number of reflections changes, t is a parameter, t si and t ei are the t values corresponding to the starting point and end point of the i-th straight line segment respectively;

[0017] Step 103: Calculate the coordinates of the center point of the positioning pin (c xi ,c zi ):

[0018] Upper row positioning pins: c xi =x i ,c zi =HR p / sin(α / 2); lower row positioning pins: c xi =x i ,c zi =R p / sin(α / 2);

[0019] According to the position coordinates and actual size of the positioning pins, an arc is used to replace the turning angle formed by the light at the reflection point, and the parametric equation of the arc segment when the weaving path turns is obtained:

[0020] x0(ω)=c xi +R p cosω,z0(ω)=c zi +R p sinω,ω∈[ω si ,ω ei ]

[0021] Where ω is a parameter, si and ω ei are the ω values corresponding to the starting point and end point of the i-th turning arc segment, respectively. When the cumulative length of the straight segment and the arc segment reaches the preset total length L, the light propagation terminates. From this, the weaving path of the spiral metal wire on the nail plate and its parameterized equation can be obtained.

[0022] Furthermore, step 2 includes the following steps:

[0023] Step 201: Determine the trajectory of the rolled or folded mapping surface:

[0024] 1) For the winding method, the winding trajectory forms an Archimedean spiral, and its Cartesian coordinate equation is:

[0025] x=(a+bθ)cosθ, y=(a+bθ)sinθ

[0026] Where a is the distance from the starting point of the spiral to the origin of the polar coordinates, and its value depends on the inner diameter of the metal rubber part; b is the increase in the spiral radius per unit angle increase, and its value depends on the number of layers of the metal rubber part; θ is the angle of rotation of the spiral;

[0027] 2) For the folding method, the folding trajectory is a U-shaped curve formed by alternating straight lines and semicircles. The curve equation is a piecewise function. Let the length of the straight line segment of the folding trajectory be L0 and the radius of the semicircle be R0. Taking the first U-shaped curve as an example, the Cartesian coordinate equation is:

[0028] Straight line segment 1: x s =u,y s =0,u∈[0,L0];

[0029] Semicircular trajectory segment 1: x s =L0+R0cosγ,y s =R0sinγ, γ∈[-π / 2,π / 2];

[0030] Straight line segment 2: x s =L0-u,y s =2R0,u∈[0,L0]

[0031] Step 202: Convert the nail plate weaving plane to the rolled or folded surface through surface mapping, and establish the following mapping relationship:

[0032] 1) Regarding the rolling method:

[0033] When the path is a straight line segment, it is expressed as θ=θ(t), t∈[t si ,t ei ];

[0034] When the path is a corner arc segment, it is expressed as θ=θ(ω), ω∈[ω si ,ω ei ];

[0035] 2) For folding method:

[0036] When the path is a straight line segment, it is represented by x s =x s (t), y s =y s (t), t∈[t si ,t ei ];

[0037] When the path is a corner arc segment, it is represented by x s =x s (ω),ys =y s (ω),ω∈[ω si ,ω ei ];

[0038] Step 203: Based on the obtained winding or folding mapping relationship, the two-dimensional plane path is spatially reconstructed to obtain the three-dimensional spiral baseline equation:

[0039] 1) For the winding method, the three-dimensional baseline equation of the straight line segment of the path is:

[0040]

[0041] The three-dimensional baseline equation of the path arc segment is:

[0042]

[0043] 2) For the folding method, the mapped (x s ,y s ) as the XY coordinates of the three-dimensional baseline, the three-dimensional baseline equation of the path straight segment is x = x s (t), y = y s (t), z=z0(t); the three-dimensional baseline equation of the path arc segment is x=x s (ω), y=y s (ω), z=z0(ω).

[0044] Furthermore, step 3 includes the following steps:

[0045] Step 301: Using the chain rule, the parametric equation obtained in step 203 is differentiated with respect to variables t and ω to obtain the direction vector T of the three-dimensional spiral baseline:

[0046] For straight line segments of a path,

[0047] For path arc segments,

[0048] Step 302: The metal wire constructs a spiral structure along the three-dimensional spiral baseline. Assume that the target point P on the metal wire performs circular motion around the baseline at a certain angular velocity. A local coordinate system O1xyz is established based on the plane of the circular motion. The parametric equations for the direction vector T1 of the three-dimensional spiral baseline and the coordinates P1 (x1, y1, z1) of the point P on the spiral metal wire in the local coordinate system are obtained:

[0049]

[0050] Where r0 is the radius of the helical coil, and β is the angle of rotation of the helical coil;

[0051] Step 303: The coordinate vector of the spiral wire in the local coordinate system Transform the space transformation R to the global coordinate system, and use the vector operation rule to obtain the coordinate vector of the spiral wire in the global coordinate system That is, the spatial coordinates P(x, y, z) of the initial blank model in the global coordinate system are obtained. The parameters are expressed as follows:

[0052]

[0053] Where x b 、y b and z b is the spatial coordinate of the baseline, and its value is given by the baseline equation in step 203, n=(n x ,n y ,n z ) is the spatial transformation rotation axis, which can be given by the cross product of vector T0 and vector T, is the angle between vector T1 and vector T.

[0054] Furthermore, step 4 includes the following steps:

[0055] Step 401: Import the initial blank model obtained in step 3 into LS-DYNA, set the beam element and material properties; add upper and lower platens, build a jacket model on the outer edge of the initial blank model, and set the internal core shaft according to the size of the metal rubber, and set it as a rigid body divided by solid elements;

[0056] Step 402: setting contact relationships between the metal wires, between the metal wires and the outer shell model, between the metal wires and the core shaft, and between the metal wires and the upper and lower platens, and using the outer shell model to extrude the initial blank model from the outside to the inside to the designed position, thereby obtaining a blank structure in which the metal wires are embedded with each other;

[0057] Step 403: Use a dynamic explicit algorithm to simulate the cold stamping process, control the upper and lower platens to extrude the blank structure, and perform multi-stage stamping and springback simulations until the blank structure is stamped to the target height and fixed. Only the stamped blank structure is retained, and the remaining parts are removed to obtain a metal-rubber microscopic finite element model.

[0058] Furthermore, in step 402, the spiral metal wires of the blank structure are completely connected as a whole, and the contact relationship between the metal wires is set to self-contact; no contact is set between the jacket models and the jacket models, between the jacket models and the upper and lower pressure plates, and between the core shaft and the upper and lower pressure plates, and they can penetrate freely; the hooking and embedding between the metal wires is achieved by extrusion of the jacket model.

[0059] Furthermore, in step 403, a segmented bidirectional stamping and springback loading method is adopted to perform multiple stamping simulations on the blank structure until the blank structure no longer undergoes recovery deformation after being stamped to a specified position.

[0060] Compared with the prior art, the effects and benefits of the present invention are:

[0061] 1. A method for generating continuous trajectories of spiral metal wires based on the actual weaving process path is proposed. This method effectively solves the problem that the winding method and discrete iterative splicing strategy have significant deviations from the actual continuous weaving process and are difficult to accurately construct the nail-plate woven metal rubber blank structure. This ensures a high degree of consistency between the metal wire trajectory in the blank structure and the actual weaving process.

[0062] 2. A three-dimensional spiral baseline is generated by surface mapping, and the material is stamped using a segmented bidirectional stamping and rebound loading method. This conforms to the actual production method of rolling or folding the blank structure to obtain the nail plate weaving process, and then stamping it. The established model can characterize the structural characteristics of the metal rubber, solving the problem that the nail plate weaving type metal rubber is difficult to model and simulate. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a flow chart of a metal rubber microscopic simulation modeling method according to an embodiment of the present invention;

[0064] Figure 2 A comparison diagram of the generated path trajectory and the nail board weaving example of an embodiment of the present invention;

[0065] Figure 3 A schematic diagram of a three-dimensional spiral baseline according to an embodiment of the present invention;

[0066] Figure 4 A comparison diagram of the initial blank model and the actual blank structure of an embodiment of the present invention;

[0067] Figure 5 A schematic diagram of a stamping simulation according to an embodiment of the present invention;

[0068] Figure 6 This is a comparison diagram between the microscopic finite element model and the actual morphology of an embodiment of the present invention. DETAILED DESCRIPTION

[0069] The present invention will be further explained below with reference to examples in the accompanying drawings.

[0070] Example 1

[0071] A braided metal rubber molding simulation method, such as Figure 1 As shown, the following steps are included:

[0072] Step 1: Construct a spiral wire weaving path generation algorithm based on the law of light reflection to ensure the consistency of the generated path with the actual weaving process path of the nail board;

[0073] In this embodiment, the metal material used to prepare the metal rubber is austenitic stainless steel 0Cr18Ni9Ti. The relevant preparation parameters and braiding process parameters are shown in Table 1. The effective width and length of the nail plate are determined by the braiding conditions. The total length L of the braiding path can be calculated and determined based on the component weight, wire diameter, spiral coil radius, and tensile pitch.

[0074] Table 1 Preparation parameters and braiding process parameters of metal rubber in Example

[0075]

[0076] Note: The size parameters of circular metal rubber are: outer diameter × inner diameter × height; the size parameters of square metal rubber are: length × height × width.

[0077] like Figure 2 As shown in (a), a rectangular area is constructed with the effective width H and effective length W of the nail board as the edges. The edges of the rectangle are the boundaries of the nail board. The length direction is the X axis, the width direction is the Z axis, and the lower left corner is point O. The XOZ coordinate system is established. Assume that the light enters from point O, and the initial incident direction is:

[0078] v=(v x ,v z )=(cosα,sinα)

[0079] Where v x and v z are the components of the light direction vector on the X-axis and Z-axis respectively; taking the nail plate boundary as the reflective mirror, the straight line segment of the weaving path is constructed through the path trajectory formed by the reflection phenomenon of the light in the closed rectangular space, thereby obtaining the parametric equation of the straight line segment of the weaving path:

[0080] x0(t)=x i ±v x t, z0(t)=z i ±v z t, t∈[t si ,t ei ]

[0081] Where x i 、z i represents the intersection of the light and the boundary of the nail plate at the i-th reflection, ± represents the change in the direction of the light as the number of reflections changes, t is a parameter, t si and t ei are the t values corresponding to the starting point and end point of the i-th straight line segment respectively; calculate the coordinates of the center point of the positioning pin (cxi ,c zi ):

[0082] Upper row positioning pins: c xi =x i ,c zi =HR p / sin(α / 2); lower row positioning pins: c xi =x i ,c zi =R p / sin(α / 2);

[0083] According to the position coordinates and actual size of the positioning pins, an arc is used to replace the turning angle formed by the light at the reflection point, and the parametric equation of the arc segment when the weaving path turns is obtained:

[0084] x0(ω)=c xi +R p cosω,z0(ω)=c zi +R p sinω,ω∈[ω si ,ω ei ]

[0085] Where ω is a parameter, si and ω ei are the ω values corresponding to the starting point and end point of the i-th turning arc segment respectively; when the cumulative length of the straight line segment and the arc segment reaches the preset total length L, the light propagation ends, thus the weaving path of the spiral metal wire on the nail plate and its parameterized equation can be obtained; the actual nail plate weaving path is as follows Figure 2 As shown in (b), the generated weaving trajectory is highly consistent with the actual weaving process.

[0086] Step 2: Based on the blank rolling or folding process, the surface mapping algorithm is used to reconstruct the three-dimensional space mapping of the spiral wire plane baseline trajectory, such as Figure 3 As shown;

[0087] (1) Regarding the rolling method:

[0088] When the path is a straight line segment, it is expressed as θ=θ(t), t∈[t si ,t ei ];

[0089] When the path is a corner arc segment, it is expressed as θ=θ(ω), ω∈[ω si ,ω ei ];

[0090] According to the obtained winding mapping relationship, the two-dimensional plane path is spatially reconstructed to obtain the three-dimensional spiral baseline equation, where the three-dimensional baseline equation of the straight segment of the braiding path is:

[0091]

[0092] The three-dimensional baseline equation of the arc segment of the knitting path is:

[0093]

[0094] Thus, while ensuring that the spatial winding angle and pitch distribution of the baseline before and after the transformation remain unchanged, it can also ensure the high consistency between the blank preparation method and the actual process, and obtain the three-dimensional spiral baseline such as Figure 3 (a)

[0095] (2) Regarding folding method:

[0096] When the path is a straight line segment, it is represented by x s =x s (t), y s =y s (t), t∈[t si ,t ei ];

[0097] When the path is a corner arc segment, it is represented by x s =x s (ω),y s =y s (ω),ω∈[ω si ,ω ei ];

[0098] The mapped (x s ,y s ) as the XY coordinates of the three-dimensional baseline, the three-dimensional baseline equation of the path straight segment is x = x s (t), y = y s (t), z=z0(t), and the three-dimensional baseline equation of the path arc segment is x=x s (ω), y=y s (ω), z=z0(ω), while ensuring that the spatial winding angle and pitch distribution of the baseline before and after the transformation remain unchanged, ensuring the high consistency between the blank preparation method and the actual process, the three-dimensional spiral baseline is obtained as follows Figure 3 (b) shown.

[0099] Step 3: Use spatial transformation along the three-dimensional baseline to construct the metal wire spiral structure and reconstruct the spatial topological relationship of the spiral turns, thereby obtaining the parameterized equation of the spiral metal wire and the initial blank model, such as Figure 4 As shown;

[0100] By using the chain rule, the path parameter equation obtained in step 2 is differentiated with respect to the variables t and ω to obtain the direction vector T of the three-dimensional spiral baseline:

[0101] For straight line segments of a path,

[0102] For path arc segments,

[0103] After obtaining the baseline direction vector, a wire spiral structure is constructed along the three-dimensional spiral baseline. The spiral wire is assumed to perform circular motion around the baseline at a certain angular velocity. The local coordinate system O1xyz is established based on the plane of the circular motion. The parametric equations for the direction vector T1 of the three-dimensional spiral baseline and the coordinates P1 (x1, y1, z1) of the point P on the spiral wire in the local coordinate system are obtained:

[0104]

[0105] Where r0 is the radius of the spiral coil, β is the angle of rotation of the spiral coil; the coordinate vector of the spiral wire in the local coordinate system is Transform the space transformation R to the global coordinate system, and use the vector operation rule to obtain the coordinate vector of the spiral wire in the global coordinate system That is, the spatial coordinates P(x, y, z) of the initial blank model in the global coordinate system are obtained. The parameters are expressed as follows:

[0106]

[0107] Where x b 、y b and z b is the spatial coordinate of the baseline, and its value is given by the baseline equation in step 203, n=(n x ,n y ,n z ) is the spatial transformation rotation axis, which can be given by the cross product of vector T0 and vector T, is the angle between vector T1 and vector T; thus, the comparison between the initial rolling blank model and the corresponding actual blank structure is obtained. Figure 4 As shown in (a) and (b), the folded initial blank model is compared with the corresponding actual blank structure. Figure 4 As shown in (c) and (d).

[0108] Step 4: Import the initial blank model obtained in step 3 into the LS-DYNA software and perform forming simulation step by step in the explicit dynamics solver;

[0109] First, add material properties, and the spiral metal wire of the blank structure is completely connected as a whole. The blank model is set as a beam unit and given a circular cross-section with a diameter equal to the wire diameter. Add upper and lower pressure plates, establish a jacket model on the outer edge of the initial blank model, and set the internal core shaft according to the size of the metal rubber. Except for the blank model, the remaining parts are set as rigid bodies divided by solid units. The stamping models of the circular ring and square metal rubber blank are obtained as follows: Figure 5 As shown in (a) and (b);

[0110] Then, contact relationships are set between the metal wires, between the metal wires and the outer shell model, between the metal wires and the core shaft, and between the metal wires and the upper and lower platens, wherein the contact relationship between the metal wires is set to self-contact; no contact is set between the outer shell models, between the outer shell models and the upper and lower platens, and between the core shaft and the upper and lower platens, allowing free penetration; the outer shell model is used to extrude the initial blank model from the outside to the inside to the designed position, thereby obtaining a blank structure in which the metal wires are embedded in each other;

[0111] The dynamic explicit algorithm is used to simulate the cold stamping process, the upper and lower platens are controlled to extrude the blank structure, and the segmented bidirectional stamping and rebound loading method is used to perform multiple stamping simulations on the blank structure. Figure 5 As shown in (c) and (d), after the blank structure is stamped to the specified position, no recovery deformation occurs. Only the blank structure after stamping is retained, and the rest of the structure is removed. Finally, the circular and square metal rubber microscopic finite element models are obtained. The comparison between the two and the actual metal rubber parts is as follows: Figure 6 shown.

[0112] The final mass of the circular metal rubber simulation part is 104.5g, which deviates from the actual mass by 1.5%; the mass of the square metal rubber simulation part is 24.35g, which deviates from the actual mass by 0.6%.

[0113] The above description is merely a disclosed embodiment of the present invention and does not limit the present invention in any form. Any modifications, equivalent changes and modifications made by any person skilled in the art based on the essential contents of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A nail plate braided metal rubber molding simulation method, characterized in that: The following steps are involved: Step 1: Based on the law of light reflection, an algorithm for generating the spiral wire braiding path is constructed to ensure that the generated path is consistent with the actual braiding process path of the nail plate. The curvature of the generated path is adjusted according to the position of the positioning pins to ensure a continuous and smooth transition of the path. This establishes the braiding path of the spiral wire on the nail plate and its parameterized equation, thereby obtaining the baseline trajectory of the spiral wire within the nail plate braiding plane. Step 2: Based on the blank rolling or folding process, a surface mapping algorithm is used to perform a three-dimensional spatial mapping reconstruction of the spiral wire's planar baseline trajectory to ensure that the spatial winding angle and pitch distribution of the baseline before and after the transformation remain unchanged, while ensuring the consistency of the blank preparation method with the actual process. The two-dimensional planar path of the spiral wire is converted into a three-dimensional spiral baseline to obtain a three-dimensional baseline equation. The rolling process is used for simulating cylindrical or toroidal metal rubber parts, and the folding process is used for simulating square metal rubber parts. The rolling or folding is performed along the length direction of the nail plate. Step 3: Use spatial transformation along the three-dimensional baseline to construct the metal wire spiral structure and reconstruct the spatial topological relationship of the spiral turns, thereby obtaining the parameterized equation of the spiral metal wire and the initial blank model; Step 4: Import the initial blank model into the finite element software and perform forming simulation in two steps using the explicit dynamics solver. First, quasi-statically extrude the initial blank model to obtain a blank structure with embedded metal wires. Then, a dynamic explicit algorithm is used to simulate the cold stamping process to obtain a metal-rubber microscopic finite element model.

2. The nail plate braided metal rubber molding simulation method according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 101: Determine the total length L of the braiding path, the angle α between the braiding path and the length direction of the nail plate, and the radius R of the positioning nail based on the metal rubber preparation parameters and the braiding process. p , the effective width H and effective length W of the nail plate; Step 102: With the effective width H and effective length W of the nail board as the sides, construct a rectangular area as the effective area of the nail board. The sides of the rectangle are the boundaries of the nail board, the length direction is the X axis, the width direction is the Z axis, and the lower left corner is point O. Establish the XOZ coordinate system. Assume that the light enters from point O. The direction vector of the initial incident direction is: v=(v x ,v z )=(cosα,sinα) Where v x and v z are the components of the light direction vector on the X-axis and Z-axis respectively; taking the nail plate boundary as the reflective mirror, the straight line segment of the weaving path is constructed through the path trajectory formed by the reflection phenomenon of the light in the closed rectangular space, thereby obtaining the parametric equation of the straight line segment of the weaving path: x0(t)=x i ±v x t,z0(t)=z i ±v z t,t∈[t si ,t ei ] Where x i 、z i represents the intersection of the light and the boundary of the nail plate at the i-th reflection, ± represents the change in the direction of the light as the number of reflections changes, t is a parameter, t si and t ei are the t values corresponding to the starting point and end point of the i-th straight line segment respectively; Step 103: Calculate the coordinates of the center point of the positioning pin (c xi ,c zi ): Upper row positioning pins: c xi =x i ,c zi =HR p / sin(α / 2); lower row positioning pins: c xi =x i ,c zi =R p / sin(α / 2); According to the position coordinates and actual size of the positioning pins, an arc is used to replace the turning angle formed by the light at the reflection point, and the parametric equation of the arc segment when the weaving path turns is obtained: x0(ω)=c xi +R p cosω,z0(ω)=c zi +R p sinω,ω∈[ω si ,oh ei ] Where ω is a parameter, si and ω ei are the ω values corresponding to the starting point and end point of the i-th turning arc segment, respectively. When the cumulative length of the straight segment and the arc segment reaches the preset total length L, the light propagation terminates. Thus, the weaving path of the spiral metal wire on the nail plate and its parameterized equation are obtained.

3. The nail plate braided metal rubber molding simulation method according to claim 2, characterized in that: Step 2 specifically includes the following steps: Step 201: Determine the trajectory of the rolled or folded mapping surface: 1) For the winding method, the winding trajectory forms an Archimedean spiral, and its Cartesian coordinate equation is: x=(a+bθ)cosθ, y=(a+bθ)sinθ Where a is the distance from the starting point of the spiral to the origin of the polar coordinates, and its value depends on the inner diameter of the metal rubber part; b is the increase in the spiral radius per unit angle increase, and its value depends on the number of layers of the metal rubber part; θ is the angle of rotation of the spiral; 2) For the folding method, the folding trajectory is a U-shaped curve formed by alternating straight lines and semicircles. The curve equation is a piecewise function. Let the length of the straight line segment of the folding trajectory be L0 and the radius of the semicircle be R0. Taking the first U-shaped curve as an example, the Cartesian coordinate equation is: Straight line segment 1: x s =u,y s =0,u∈[0,L0]; Semicircular trajectory segment 1: x s =L0+R0cosγ,y s =R0sinγ, γ∈[-π / 2,π / 2]; Straight line segment 2: x s =L0-u,y s =2R0,u∈[0,L0] Step 202: Map the nailboard weave plane to the rolled or folded surface: 1) Regarding the rolling method: When the path is a straight line segment, it is expressed as θ=θ(t), t∈[t si ,t ei ]; When the path is a corner arc segment, it is expressed as θ=θ(ω), ω∈[ω si ,ω ei ]; 2) For folding method: When the path is a straight line segment, it is represented by x s =x s (t), y s =y s (t), t∈[t si ,t ei ]; When the path is a corner arc segment, it is represented by x s =x s (ω),y s =y s (ω),ω∈[ω si ,ω ei ]; Step 203: Based on the obtained winding or folding mapping relationship, the two-dimensional plane path is spatially reconstructed to obtain the three-dimensional spiral baseline equation: 1) For the winding method, the three-dimensional baseline equation of the straight line segment of the path is: The three-dimensional baseline equation of the path arc segment is: 2) For the folding method, the mapped (x s ,y s ) as the XY coordinates of the three-dimensional baseline, the three-dimensional baseline equation of the path straight segment is x = x s (t), y = y s (t), z=z0(t); the three-dimensional baseline equation of the path arc segment is x=x s (ω), y=y s (ω), z=z0(ω).

4. The nail plate braided metal rubber molding simulation method according to claim 3, characterized in that: Step 3 includes the following steps: Step 301: Using the chain rule, the parametric equation obtained in step 203 is differentiated with respect to variables t and ω to obtain the direction vector T of the three-dimensional spiral baseline: For straight line segments of a path, For path arc segments, Step 302: The metal wire constructs a spiral structure along the three-dimensional spiral baseline. Assume that the target point P on the metal wire performs circular motion around the baseline at a certain angular velocity. A local coordinate system O1xyz is established based on the plane of the circular motion. The parametric equations for the direction vector T1 of the three-dimensional spiral baseline and the coordinates P1 (x1, y1, z1) of the point P on the spiral metal wire in the local coordinate system are obtained: Where r0 is the radius of the helical coil, and β is the angle of rotation of the helical coil; Step 303: The coordinate vector of the spiral wire in the local coordinate system Transform the space transformation R to the global coordinate system, and use the vector operation rule to obtain the coordinate vector of the spiral wire in the global coordinate system That is, the spatial coordinates P(x, y, z) of the initial blank model in the global coordinate system are obtained. The parameters are expressed as follows: Where x b 、y b and z b is the spatial coordinate of the baseline, and its value is given by the baseline equation in step 203, n=(n x ,n y ,n z ) is the spatial transformation rotation axis, which is given by the cross product of vector T0 and vector T, is the angle between vector T1 and vector T.

5. The nail plate braided metal rubber molding simulation method according to claim 4, characterized in that: Step 4 specifically includes the following steps: Step 401: Import the initial blank model obtained in step 3 into LS-DYNA software, set the beam element and material properties; add upper and lower platens, build a jacket model along the outer edge of the initial blank model, and set the internal core shaft according to the size of the metal rubber, and set it as a rigid body divided by solid elements; Step 402: setting contact relationships between the metal wires, between the metal wires and the outer shell model, between the metal wires and the core shaft, and between the metal wires and the upper and lower platens, and using the outer shell model to extrude the initial blank model from the outside to the inside to the designed position, thereby obtaining a blank structure in which the metal wires are embedded with each other; Step 403: Use a dynamic explicit algorithm to simulate the cold stamping process, control the upper and lower platens to extrude the blank structure, and perform multi-stage stamping and springback simulations until the blank structure is stamped to the target height and fixed. Only the stamped blank structure is retained, and the remaining parts are removed to obtain a metal-rubber microscopic finite element model.

6. The nail plate braided metal rubber molding simulation method according to claim 5, characterized in that: In step 402, the spiral metal wires of the blank structure are completely connected as a whole, and the contact relationship between the metal wires is set to self-contact; there is no contact between the outer shell models, between the outer shell models and the upper and lower pressure plates, and between the core shaft and the upper and lower pressure plates, and they can penetrate freely; the hooking and embedding between the metal wires is achieved by extrusion of the outer shell model.

7. A nail plate braided metal rubber molding simulation method according to any one of claims 5 or 6, characterized in that: In step 403, a segmented bidirectional stamping and springback loading method is used to perform multiple stamping simulations on the blank structure until the blank structure no longer undergoes recovery deformation after being stamped to a specified position.

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