Method for establishing screw finite element model, electronic device and storage medium

Abstract

A method for establishing a screw finite element model, an electronic device and a storage medium, relate to the technical field of finite element model establishment. It includes: importing a screw geometric model into modeling software; obtaining coordinates of screw shape geometry in the screw geometric model, including: obtaining coordinates of a screw cap and screw rod interface in the screw and coordinates of a centroid of a screw entity; determining the orientation of the screw rod; establishing a grid auxiliary line using geometric dimensions and coordinate information; establishing a two-dimensional grid model of the screw; and establishing a three-dimensional grid model of the screw. By obtaining the coordinates of the screw shape geometry in the screw geometric model, identifying the coordinates of the screw cap and screw rod interface in the screw and the coordinates of the centroid of the screw entity, determining the orientation of the screw rod, and establishing the two-dimensional and three-dimensional grid models of the screw, the purpose of quickly, batch and automatically establishing the finite element model of the screw is achieved.

Description

Technical Field

[0001] This application relates to the field of finite element model building technology, and in particular to a method, electronic device and storage medium for building a finite element model of a screw. Background Technology

[0002] Currently, with the rapid development of the consumer electronics industry, characterized by short product cycles, rapid product updates, and large shipment volumes, the reliability of the overall structure is particularly important. In the early stages of product mold making, structural simulation is needed to expose and optimize design risks, minimizing the risk of major irreparable damage after mold making. This places high demands on the efficiency of overall system simulation. In overall system finite element simulation, the model consists of approximately 220 parts, and screws are essential structural components used for fastening in current consumer electronics products. Traditional methods for building finite element models of screws are time-consuming, labor-intensive, and involve repetitive work. Therefore, how to quickly and batch-produce finite element models of screws is crucial. Summary of the Invention

[0003] Based on this, this application provides a method, electronic device, and storage medium for establishing finite element models of screws, so as to achieve the purpose of establishing finite element models of screws quickly, in batches, and automatically.

[0004] On the one hand, this application provides a method for establishing a finite element model of a screw, including the following steps: importing the screw geometric model into modeling software; obtaining the coordinates of the screw's external geometry in the screw geometric model, including: obtaining the coordinates of the interface between the nut and the screw and the coordinates of the centroid of the screw entity; determining the screw orientation; establishing mesh auxiliary lines using geometric dimensions and coordinate information; establishing a two-dimensional mesh model of the screw; and establishing a three-dimensional mesh model of the screw.

[0005] According to one embodiment provided in this application, obtaining the coordinates of the screw's external geometry in a screw geometric model includes: obtaining the coordinates of the interface between the nut and the screw and the coordinates of the centroid of the screw entity; it also includes: obtaining the screw length L; obtaining the nut diameter R; obtaining the nut thickness value, first extracting the ID number Surf1 of the upper surface of the nut and the ID number Surf2 of the lower surface of the nut in a single screw, and then obtaining the nut thickness value based on the coordinates of Surf1 and Surf2.

[0006] According to an embodiment provided in this application, obtaining the coordinates of the interface between the nut and the screw and the coordinates of the centroid of the screw entity includes: obtaining the coordinates of the interface; when the screw length direction is parallel to the T-axis, obtaining the coordinates of all modeling feature points on Surf1 and Surf2; firstly, storing the coordinates of all modeling feature points on one of the faces in an empty list, setting a tolerance R, and comparing it with the screw's external dimensions Tmax and Tmin; when an element Ti in the list satisfies Tmin+R≤Ti≤Tmax-R, it can be determined which face in Surf1 and Surf2 is located at the interface between the nut and the screw, thus obtaining the coordinates Tsplit of the interface; obtaining the centroid coordinates; creating the centroid of the screw entity and obtaining the centroid coordinates Tmass; obtaining the screw diameter R2; dividing the screw entity perpendicular to the T-axis at the centroid to obtain two geometric sub-models; obtaining the maximum external dimensions of the two geometric sub-models respectively, thus obtaining the screw diameter R2.

[0007] According to one embodiment provided in this application, determining the screw orientation includes: determining the size of the screw's Tmass and Tsplit; when Tmass is less than Tsplit, the nut is on top, i.e., the screw is facing down; when Tmass is greater than Tsplit, the nut is on the bottom, i.e., the screw is facing up.

[0008] According to one embodiment provided in this application, establishing grid auxiliary lines using geometric dimensions and coordinate information includes: creating a circle with a diameter equal to the nut diameter R parallel to the T-axis at the T-split point, and obtaining the geometric number ID1 of the circle; setting a tolerance variable r, creating a circle with a diameter equal to the screw diameter minus the tolerance r parallel to the T-axis at the T-split point, and obtaining the geometric number ID2 of the circle; creating a circle between the two circles with geometric numbers ID1 and ID2, and obtaining the geometric number ID3 of the circle; creating a circle with a diameter smaller than the diameter of geometric number ID2, and obtaining the geometric number ID4 of the circle.

[0009] According to one embodiment provided in this application, establishing a two-dimensional mesh model of a screw includes: creating 8 nodes equally on each of the four circles from the inside out, with geometric numbers ID1, ID2, ID3, and ID4, and obtaining the coordinates of each node; starting from the nodes on the outermost circle with geometric number ID1 and the second circle with geometric number ID3, selecting 2 nodes of geometric number ID1 and 2 nodes corresponding to geometric number ID3 in sequence to create a quadrilateral mesh, and so on, to generate the 8 quadrilateral meshes of the outer circle; then connecting the first and last nodes sequentially from the second circle with geometric number ID3 to the third circle with geometric number ID2, from the third circle with geometric number ID2 to the fourth circle with geometric number ID4, and from the fourth circle with geometric number ID4 to the center point to create a quadrilateral mesh.

[0010] According to one embodiment provided in this application, establishing a three-dimensional mesh model of a screw includes: first, stretching the nut mesh, that is, stretching the outermost ring geometry ID1, the second ring geometry ID3, the third ring geometry ID2, the innermost ring geometry ID4, and the mesh already created at the center point upwards or downwards to generate the nut mesh; then stretching the screw mesh, that is, stretching the third ring geometry ID2, the innermost ring geometry ID4, and the mesh already created at the center point downwards or upwards to generate the screw mesh.

[0011] According to one embodiment provided in this application, when the screw length direction is parallel to the T-axis, obtaining the coordinates of all modeling feature points on Surf1 and Surf2 includes: obtaining the coordinates of all modeling feature points on Surf1 and Surf2 when the screw length direction is parallel to the X-axis; or, obtaining the coordinates of all modeling feature points on Surf1 and Surf2 when the screw length direction is parallel to the Y-axis; or, obtaining the coordinates of all modeling feature points on Surf1 and Surf2 when the screw length direction is parallel to the Z-axis; or, obtaining the coordinates of all modeling feature points on Surf1 and Surf2 when the screw length direction is parallel to any axis intersecting the X-axis, Y-axis, or Z-axis.

[0012] On the other hand, this application provides an electronic device including a memory and a processor interconnected, wherein the memory stores a computer program, which, when executed by the processor, is used to implement the steps of the method for establishing the screw finite element model described above.

[0013] In another aspect, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the above-described method for establishing a screw finite element model.

[0014] The beneficial effects of adopting the technical solution of this application are as follows: by obtaining the coordinates of the screw's external geometry in the screw geometric model, identifying the coordinates of the interface between the nut and the screw and the coordinates of the centroid of the screw entity, determining the screw orientation, and establishing two-dimensional and three-dimensional mesh models of the screw, the finite element model of the screw can be established quickly, in batches, and automatically. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0016] Figure 1This is a flowchart illustrating an embodiment of the method for establishing a screw finite element model according to this application;

[0017] Figure 2 yes Figure 1 A schematic diagram of the process of S20 in the illustrated embodiment;

[0018] Figure 3 yes Figure 2 A schematic diagram of the process of S21 in the illustrated embodiment;

[0019] Figure 4 yes Figure 2 A schematic diagram of the process of S22 in the illustrated embodiment;

[0020] Figure 5 yes Figure 2 A schematic diagram of the process of S23 in the illustrated embodiment;

[0021] Figure 6 yes Figure 2 A flowchart illustrating S24 in the illustrated embodiment;

[0022] Figure 7 yes Figure 2 A schematic diagram of the process of S25 in the illustrated embodiment;

[0023] Figure 8 yes Figure 1 A schematic diagram of the process of S30 in the illustrated embodiment;

[0024] Figure 9 yes Figure 1 A schematic diagram of the process of S40 in the illustrated embodiment;

[0025] Figure 10 yes Figure 1 A schematic diagram of the process of S50 in the illustrated embodiment;

[0026] Figure 11 yes Figure 1 A schematic diagram of the process of S60 in the illustrated embodiment;

[0027] Figure 12 This is a schematic flowchart of another embodiment of the method for establishing a screw finite element model in this application;

[0028] Figure 13 This is a schematic diagram of the structure of an embodiment of the electronic device of this application;

[0029] Figure 14 This is a schematic diagram of the structure of an embodiment of the computer-readable storage medium of this application. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0031] Please see Figure 1 , Figure 1 This is a schematic flowchart illustrating an embodiment of the method for establishing a finite element model of a screw according to this application. The method includes the following steps:

[0032] S10: Import the screw geometry model into the modeling software.

[0033] Specifically, a finite element model is a model established using the finite element analysis method. It is a combination of elements that are connected only at the nodes, transmit forces only through the nodes, and are constrained only at the nodes.

[0034] Specifically, the modeling software used in this application is Hypermesh, a powerful CAE application package that integrates various tools required for design and analysis. Importing the screw geometric model into the modeling software involves importing the screw geometric model into Hypermesh modeling software.

[0035] S20: Obtain the coordinates of the screw's external geometry in the screw geometric model.

[0036] Specifically, because the screw is assembled with its length parallel to the T-axis, and the screw head is perpendicular to the shank, with both the top and bottom surfaces of the head being circular, the maximum geometric coordinates of the screw can be obtained through the T-axis and the U-axis (which is perpendicular to the T-axis and has both the top and bottom surfaces of the head parallel to the U-axis). This allows us to obtain the screw length L and the shank diameter R. Since the screw is assembled parallel to the T-axis, we can obtain the minimum coordinate T1 and the maximum coordinate T2 on the T-axis. Therefore, T2 and T1 give us the screw length L, i.e., L = T2 - T1. Simultaneously, because the U-axis is perpendicular to the T-axis, and the screw head is perpendicular to the shank, with both the top and bottom surfaces of the head parallel to the U-axis, we can obtain the minimum coordinate U1 and the maximum coordinate U2 on the U-axis. From U1 and U2, we can obtain the shank diameter R, i.e., R = U2 - U1.

[0037] Specifically, in the Hypermesh software, a for loop iterates through the screw geometry model, extracting all its geometric surfaces and calculating the area of ​​each surface. The areas are then sorted to extract the IDs (similar to physical addresses) of the two largest and second-largest surfaces in the screw geometry model. These IDs are represented by variables Surf1 and Surf2, which are the top and bottom surfaces of the nut. Next, the coordinates T3 and T4 of surface Surf1 on the T-axis are obtained (T3 = T4 in planar cases, T3 is not equal to T4 in curved cases), and the coordinates T5 and T6 of surface Surf2 on the T-axis are obtained (T5 = T6 in planar cases, T5 is not equal to T6 in curved cases). A list 0 is constructed: List0 = [T3, T4, T5, T6]. The list elements are sorted from largest to smallest, and the minimum value is subtracted from the maximum value in the list to obtain the nut thickness value H.

[0038] Specifically, obtain the T-axis coordinates of all modeling feature points on Surf1 and Surf2, and store them in empty list 1 and empty list 2, respectively. Set a tolerance W, and determine whether the element Ti1 in list 1 satisfies Tmin+W≤Ti≤Tmax-W. If the element Ti1 in list 1 satisfies Tmin+W≤Ti1≤Tmax-W, then Surf1 is the interface between the nut and the screw, and the T-axis coordinate of the interface is set to Tsplit. If the element Ti1 in list 1 does not satisfy Tmin+W≤Ti1≤Tmax-W, then determine whether the element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W. If the element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W, then Surf2 is the interface between the nut and the screw, and the T-axis coordinate of the interface is set to Tsplit. If element Ti2 in list 2 does not satisfy Tmin+W≤Ti2≤Tmax-W, then re-obtain the T-axis coordinates of all modeling feature points on Surf1 and Surf2 and re-evaluate.

[0039] Specifically, the centroid of the screw geometric model entity is created, and the coordinates Tmass on the T-axis of the centroid are obtained. The screw geometric model entity is then horizontally divided at the centroid perpendicular to the T-axis, with the cut surface being the section of the screw perpendicular to the T-axis, resulting in the first geometric sub-model and the second geometric sub-model. The maximum external dimensions of the first geometric sub-model and the second geometric sub-model are obtained respectively, that is, the diameters of the two geometric sub-models are obtained and arranged from smallest to largest. The minimum value is then the screw diameter R2.

[0040] Because the screws are assembled parallel to the T-axis during assembly, and the screw nut and shank are perpendicular, with both the nut and shank being cylindrical and both the top and bottom surfaces of the nut being circular, the maximum geometric coordinates of the screw can be obtained through the T-axis and the U-axis (which is perpendicular to the T-axis and parallel to the U-axis). Since the screw is assembled parallel to the T-axis, and the U-axis is perpendicular to the T-axis, and the screw nut is perpendicular to the shank (meaning both the top and bottom surfaces of the nut are parallel to the U-axis), when the screw geometric model is laterally divided at its centroid perpendicular to the T-axis to obtain the first and second geometric sub-models, the cross-section (i.e., the section of the shank perpendicular to the T-axis) is parallel to the U-axis. Therefore, the minimum coordinate Umin and maximum coordinate Umax of the first and second geometric sub-models on the U-axis can be obtained respectively. Subtracting Umin from Umax yields the maximum diameter of the first and second geometric sub-models. Arranging the maximum diameters of the first and second geometric sub-models from smallest to largest, the minimum value is the shank diameter R2.

[0041] Understandably, in some embodiments, the screw geometric model entity can be divided into two geometric sub-models at the centroid perpendicular to the T-axis. The maximum external dimensions of the two geometric sub-models are obtained respectively. First, the geometric sub-model with the largest external dimension (maximum diameter) among the first and second geometric sub-models is excluded. Then, the maximum external dimension of the other geometric sub-model is obtained, that is, the minimum coordinate Umin and the maximum coordinate Umax of the geometric sub-model on the U-axis are obtained. Umax-Umin can be used to obtain the screw diameter R2.

[0042] S30: Determine the orientation of the screw.

[0043] Specifically, obtain the coordinates Tmass of the centroid on the T-axis and the coordinates Tsplit of the interface on the T-axis. Determine the magnitudes of Tmass and Tsplit. If Tmass is greater than Tsplit, the nut is at the bottom and the screw is at the top (i.e., the nut is on the side with the smaller T value and the screw is towards the side with the larger T value); if Tmass is less than Tsplit, the nut is at the top and the screw is at the bottom (i.e., the nut is on the side with the larger T value and the screw is towards the side with the smaller T value).

[0044] It is understood that the screws discussed in this embodiment are all geometric models of screws with their center of mass on the screw shaft.

[0045] S40: Establish grid auxiliary lines using geometric dimensions and coordinate information.

[0046] Specifically, at the Tsplit point and parallel to the T-axis, create a circle with a diameter equal to the nut diameter R and obtain its geometric ID1. Set a tolerance variable w, and at the Tsplit point and parallel to the T-axis, create a circle with a diameter equal to Rw and obtain its geometric ID2. The tolerance w represents the reduced screw size because if the mesh is built according to the actual screw diameter, there will be interference between the screw mesh and the mating parts. In this case, the screw mesh size needs to be scaled to ensure that the set screw better matches the mating parts. At the Tsplit point and parallel to the T-axis, create another circle in the middle of the annulus formed by the two circles ID1 and ID2, and obtain its geometric ID3. At the Tsplit point and parallel to the T-axis, create a circle with a diameter smaller than the screw diameter and obtain its geometric ID4. Create 8 temporary nodes equally on each of the four circles ID1, ID2, ID3 and ID4, and obtain the number of each node. The method of division is as follows: calculate the circumference of each circle by its diameter, and divide the circumference by 8 to create 8 temporary nodes equally on each circle.

[0047] S50: Create a two-dimensional mesh model of the screw.

[0048] Specifically, after creating eight temporary nodes on the four circles ID1, ID2, ID3, and ID4, two nodes are selected on the outermost circle ID1, and two corresponding nodes are selected on the second circle ID3 to create a quadrilateral mesh. Then, following this method, the nodes on circles ID1 and ID3 are used to create the outermost eight quadrilateral meshes. Next, following the same method, the nodes on circles ID3 and ID2, and the nodes on circles ID2 and ID4, are used to create the second and third rings of quadrilateral meshes from the outside in. The quadrilateral meshes formed by the nodes on ID1 and ID3, ID3 and ID2, and ID2 and ID4 are numbered IDall. Finally, the nodes on circle ID4 are connected to the center point to create a triangular mesh, numbered Idin. The two-dimensional mesh model of the screw is now complete.

[0049] S60: Create a 3D mesh model of the screw.

[0050] Specifically, select all quadrilateral meshes numbered IDall and stretch them upwards or downwards to form a screw mesh; select all triangular meshes numbered Idin (this triangular mesh can also be described as a quadrilateral mesh; when described as a quadrilateral mesh, two points of the quadrilateral overlap and one side of the quadrilateral has a length of 0), as well as the quadrilateral mesh formed by the nodes on ID2 and ID4, and stretch them downwards or upwards to form a screw mesh; the screw 3D mesh model is now complete.

[0051] Please see Figure 2 , Figure 2 yes Figure 1 The illustrated flowchart shows step S20 in some embodiments. In some embodiments, the method includes the following steps:

[0052] S21: Obtain the screw length L and the nut diameter R.

[0053] Specifically, because the screw is assembled with its length parallel to the T-axis, and the screw head is perpendicular to the shank, with both the top and bottom surfaces of the head being circular, the maximum geometric coordinates of the screw can be obtained through the T-axis and the U-axis (which is perpendicular to the T-axis and has both the top and bottom surfaces of the head parallel to the U-axis). This allows us to obtain the screw length L and the shank diameter R. Since the screw is assembled parallel to the T-axis, we can obtain the minimum coordinate T1 and the maximum coordinate T2 on the T-axis. Therefore, T2 and T1 give us the screw length L, i.e., L = T2 - T1. Simultaneously, because the U-axis is perpendicular to the T-axis, and the screw head is perpendicular to the shank, with both the top and bottom surfaces of the head parallel to the U-axis, we can obtain the minimum coordinate U1 and the maximum coordinate U2 on the U-axis. From U1 and U2, we can obtain the shank diameter R, i.e., R = U2 - U1.

[0054] Understandably, in some embodiments, the product screws are assembled with their length direction parallel to the Z-axis, the screw head is perpendicular to the screw shaft, and the screw head is cylindrical with both its top and bottom surfaces being circular. Therefore, the maximum geometric coordinates of the screw can be obtained through the Z-axis and the X-axis (which is perpendicular to the Z-axis and whose top and bottom surfaces are parallel to the X-axis), thus allowing us to obtain the screw length L and the screw head diameter R. Since the screw is assembled parallel to the Z-axis, the minimum coordinate Z1 and the maximum coordinate Z2 of the screw on the Z-axis can be obtained. Therefore, Z2 and Z1 give the screw length L, i.e., L = Z2 - Z1. Simultaneously, because the X-axis is perpendicular to the Z-axis, and the screw head is perpendicular to the screw shaft, and whose top and bottom surfaces are parallel to the Z-axis, the minimum coordinate X1 and the maximum coordinate X2 of the screw head on the X-axis can be obtained. From X1 and X2, the screw head diameter R can be obtained, i.e., R = X2 - X1. Understandably, there is also a Y-axis that is perpendicular to the X-axis and the Z-axis. By obtaining the minimum coordinate Y1 of the nut on the Y-axis and the maximum coordinate Y2 of the nut on the Y-axis, the diameter R of the nut can also be obtained from Y1 and Y2, that is, R = Y2 - Y1 (because the nut is a cylinder, X2 - X1 = Y2 - Y1, therefore, R can be calculated from either the X-axis or the Y-axis).

[0055] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and the U-axis of this application is the axis perpendicular to the X-axis, Y-axis, Z-axis or any axis. This application can obtain the screw length and nut diameter through the T-axis and U-axis.

[0056] S22: Take the thickness value of the nut.

[0057] Specifically, in the Hypermesh software, a for loop iterates through the screw geometry model, extracting all its geometric surfaces and calculating the area of ​​each surface. The areas are then sorted to extract the IDs (similar to physical addresses) of the two largest and second-largest surfaces in the screw geometry model. These IDs are represented by variables Surf1 and Surf2, which are the top and bottom surfaces of the nut. Because the screw is assembled parallel to the T-axis, and the nut is perpendicular to the screw shaft, and the nut is cylindrical, with both Surf1 and Surf2 being circular, the coordinates of Surf1 and Surf2 on the T-axis can be obtained directly from the screw geometry. Obtain the coordinates T3 and T4 of the Surf1 surface on the T-axis (T3 = T4 in the case of a plane, T3 is not equal to T4 in the case of a curved surface), and then obtain the coordinates T5 and T6 of the Surf2 surface on the T-axis (T5 = T6 in the case of a plane, T5 is not equal to T6 in the case of a curved surface). Construct list 0, i.e., List0 = [T3, T4, T5, T6]. Sort the list elements in descending order, and subtract the minimum value from the maximum value in the list. The result is the nut thickness value H.

[0058] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and this application can obtain the thickness value H of the nut through the T-axis.

[0059] S23: Obtain the coordinates of the interface between the nut and the screw in the screw.

[0060] Specifically, because the product screws are assembled with their length direction parallel to the T-axis, and the screw nut and shank are perpendicular, with the nut being a cylinder and both its upper and lower faces Surf1 and Surf2 being circular, the T-axis coordinates of all modeling feature points on Surf1 and Surf2 can be obtained via the T-axis. These T-axis coordinates are then stored in empty list 1 and empty list 2, respectively. A tolerance W is set, and it is determined whether the element Ti1 in list 1 satisfies Tmin+W≤Ti≤Tmax-W. When the element Ti1 in list 1 satisfies Tmin+W≤Ti1≤Tmax-W, then Surf1 is the interface between the nut and shank, and the T-axis coordinate of the interface is set to Tsplit. If element Ti1 in list 1 does not satisfy Tmin+W≤Ti1≤Tmax-W, then check if element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W. If element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W, then Surf2 is the interface between the nut and the screw, and the T-axis coordinate of the interface is set to Tsplit. If element Ti2 in list 2 does not satisfy Tmin+W≤Ti2≤Tmax-W, then re-obtain the T-axis coordinates of all modeling feature points on Surf1 and Surf2, and re-evaluate.

[0061] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and this application can obtain the interface between the nut and the screw through the T-axis.

[0062] S24: Obtain the coordinates of the centroid of the screw entity.

[0063] Specifically, because the product screws are assembled with their length direction parallel to the T-axis, and the screw nut and screw shaft are perpendicular, the centroid of the screw geometric model entity is created through an algorithm, and the coordinates Tmass on the T-axis of the centroid are obtained.

[0064] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis, or any axis. This application can obtain the centroid Tmass of the screw geometric model entity through the T-axis. The centroid of the screw geometric model entity can be Xmass, Ymass, Zmass, or any axis mass. The centroids of the screw geometric models discussed in this application are all distributed on the screw shaft.

[0065] S25: Obtain the screw diameter.

[0066] Specifically, the centroid of the screw geometric model entity is created, and the coordinates Tmass on the T-axis of the centroid are obtained. The screw geometric model entity is then horizontally divided at the centroid perpendicular to the T-axis, with the cut surface being the section of the screw perpendicular to the T-axis, resulting in the first geometric sub-model and the second geometric sub-model. The maximum external dimensions of the first geometric sub-model and the second geometric sub-model are obtained respectively, that is, the diameters of the two geometric sub-models are obtained and arranged from smallest to largest. The minimum value is then the screw diameter R2.

[0067] Because the product screws are assembled with their length direction parallel to the T-axis, and the screw nut and shank are perpendicular, with both the nut and shank being cylindrical and the nut having two circular surfaces, the maximum geometric coordinates of the screw can be obtained through the T-axis and the U-axis (which is perpendicular to the T-axis and parallel to the U-axis). The screw is assembled parallel to the T-axis. Since the U-axis is perpendicular to the T-axis, and the screw nut is perpendicular to the screw shaft (meaning the top and bottom faces of the nut are parallel to the U-axis), when the screw geometric model is laterally divided at its centroid perpendicular to the T-axis to obtain the first and second geometric sub-models, the cross-section (i.e., the section of the screw shaft perpendicular to the T-axis) is parallel to the U-axis. Therefore, the minimum coordinate Umin and maximum coordinate Umax of the first and second geometric sub-models on the U-axis can be obtained respectively. Umax - Umin yields the maximum diameter of the first and second geometric sub-models. Arranging the maximum diameters of the first and second geometric sub-models from smallest to largest, the minimum value is the screw diameter R2.

[0068] Understandably, in some embodiments, the screw geometric model entity can be divided into two geometric sub-models at the centroid perpendicular to the T-axis. The maximum external dimensions of the two geometric sub-models are obtained respectively. First, the geometric sub-model with the largest external dimension (maximum diameter) among the first and second geometric sub-models is excluded. Then, the maximum external dimension of the other geometric sub-model is obtained, that is, the minimum coordinate Umin and the maximum coordinate Umax of the geometric sub-model on the U-axis are obtained. Umax-Umin can be used to obtain the screw diameter R2.

[0069] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and the U-axis of this application is the axis perpendicular to the X-axis, Y-axis, Z-axis or any axis. This application can obtain the diameter R2 of the screw in the screw geometry model through the T-axis and U-axis.

[0070] Please see Figure 3 , Figure 3 yes Figure 2 The illustrated flowchart shows step S21 in the embodiment shown. In some embodiments, the method includes the following steps:

[0071] S211: Obtain the maximum external coordinate dimension of the screw geometry with its length direction parallel to the T-axis.

[0072] Specifically, since the product screws are assembled with their length direction parallel to the T-axis, the maximum coordinate Tmax (i.e., T2) and minimum coordinate Tmin (i.e., T1) of the screw geometry on the T-axis can be used.

[0073] S212: Obtain the screw length L by acquiring Tmax and Tmin.

[0074] Specifically, the length L of the screw can be calculated using Tmax and Tmin, where L = Tmax - Tmin, or L = T2 - T1.

[0075] S213: Create a U-axis perpendicular to the T-axis in the coordinate system.

[0076] Specifically, because the product screws are assembled with their length direction parallel to the T-axis, and the screw nut is perpendicular to the screw rod, and the nut is a cylinder with both its top and bottom surfaces being circular, a U-axis can be created perpendicular to the T-axis to obtain the diameter of the nut. Since the U-axis is perpendicular to the T-axis, and the screw nut is perpendicular to the screw rod, meaning the top and bottom surfaces of the nut are parallel to the U-axis, the minimum coordinate U1 (i.e., Umin) of the nut on the U-axis and the maximum coordinate U2 (i.e., Umax) of the nut on the U-axis can be obtained.

[0077] S214: Obtain Umax and Umin to get the nut diameter R1.

[0078] Specifically, the diameter of the nut can be calculated using Umax and Umin, R = Umax - Umin, or R = U2 - U1.

[0079] Understandably, in some embodiments, the product screws are assembled with their length direction parallel to the Z-axis, the screw head is perpendicular to the screw shaft, and the screw head is cylindrical with both its top and bottom surfaces being circular. Therefore, the maximum geometric coordinates of the screw can be obtained through the Z-axis and the X-axis (which is perpendicular to the Z-axis and whose top and bottom surfaces are parallel to the X-axis), thus allowing us to obtain the screw length L and the screw head diameter R. Since the screw is assembled parallel to the Z-axis, the minimum coordinate Z1 and the maximum coordinate Z2 of the screw on the Z-axis can be obtained. Therefore, Z2 and Z1 give the screw length L, i.e., L = Z2 - Z1. Simultaneously, because the X-axis is perpendicular to the Z-axis, and the screw head is perpendicular to the screw shaft, and whose top and bottom surfaces are parallel to the Z-axis, the minimum coordinate X1 and the maximum coordinate X2 of the screw head on the X-axis can be obtained. From X1 and X2, the screw head diameter R can be obtained, i.e., R = X2 - X1. Understandably, there is also a Y-axis that is perpendicular to the X-axis and the Z-axis. By obtaining the minimum coordinate Y1 of the nut on the Y-axis and the maximum coordinate Y2 of the nut on the Y-axis, the diameter R of the nut can also be obtained from Y1 and Y2, that is, R = Y2 - Y1 (because the nut is a cylinder, X2 - X1 = Y2 - Y1, therefore, R can be calculated from either the X-axis or the Y-axis).

[0080] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and the U-axis of this application is the axis perpendicular to the X-axis, Y-axis, Z-axis or any axis. This application can obtain the screw length and nut diameter through the T-axis and U-axis.

[0081] Please see Figure 4 , Figure 4 yes Figure 2 The illustrated embodiment shows a flowchart of step S22. In some embodiments, the method includes the following steps:

[0082] S221: Identify the top and bottom surfaces of the nut, marked as Suef1 and Suef2.

[0083] Specifically, in the Hypermesh software, a for loop is used to traverse the screw geometry model, extract all the geometric surfaces of the screw geometry model, calculate the area of ​​each surface, and then sort the areas. This allows the extraction of the ID numbers (similar to physical addresses) of the two largest and second largest surfaces in the screw geometry model. The ID numbers of the largest and second largest surfaces in the screw geometry model are represented by variables Surf1 and Surf2, which are the top and bottom surfaces of the nut.

[0084] S222: Obtain the T-axis coordinates T3 and T4 of the upper surface Surf1 of the nut.

[0085] Specifically, because the product screws are assembled parallel to the T-axis during assembly, and the screw nut and shank are perpendicular, with the nut being a cylinder and its upper surface Surf1 being circular, the coordinates of the screw geometry Surf1 on the T-axis can be obtained. The coordinates of the Surf1 surface on the T-axis are denoted as T3 and T4 (T3 = T4 in the case of a plane, but not equal to T4 in the case of a curved surface).

[0086] S223: Obtain the T-axis coordinates T5 and T6 of the lower surface Surf2 of the nut.

[0087] Specifically, because the product screws are assembled parallel to the T-axis during assembly, and the screw nut and shank are perpendicular, with the nut being a cylinder and its lower surface Surf1 being circular, the coordinates of the screw geometry Surf2 on the T-axis can be obtained through the T-axis. The coordinates of the Surf2 surface on the T-axis are denoted as T5 and T6 (T5 = T6 in the case of a plane, but not equal to T6 in the case of a curved surface).

[0088] S224: Construct a list List0 = [T3, T4, T5, T6].

[0089] Specifically, construct list 0, i.e., List0 = [T3, T4, T5, T6], and sort the list elements in descending order.

[0090] S225: Subtract the minimum value from the maximum value in the list to get the nut thickness value.

[0091] Specifically, the algorithm finds the maximum and minimum values ​​in list 0, and subtracts the minimum value from the maximum value to get the nut thickness value H.

[0092] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and this application can obtain the thickness value H of the nut through the T-axis.

[0093] Please see Figure 5 , Figure 5 yes Figure 2 The illustrated flowchart shows step S23 in some embodiments. In some embodiments, the method includes the following steps:

[0094] S231: Obtain the T-axis coordinates of all modeled feature points on Surf1 and Surf2.

[0095] Specifically, because the product screws are assembled with their length direction parallel to the T-axis, the screw nut is perpendicular to the screw rod, the nut is a cylinder, and the upper and lower surfaces Surf1 and Surf2 of the nut are both circular, the T-axis coordinates of all modeled feature points on Surf1 and Surf2 can be obtained through the T-axis.

[0096] S232: Store the T-axis coordinates of all modeled feature points on Surf1 and Surf2 in empty list 1 and empty list 2, respectively.

[0097] Specifically, the T-axis coordinates Ti1 and Ti2 of all modeled feature points on Surf1 and Surf2 are stored in empty list 1 and empty list 2, respectively.

[0098] S233: Set a tolerance W.

[0099] Specifically, a tolerance W is set. It can be understood that the purpose of setting the tolerance W here is to exclude the interface between the screw and the nut from being the first and last surfaces of the screw geometry model (i.e., the surface of the nut away from the screw and the surface of the screw away from the nut).

[0100] S234: Determine whether the element Ti1 in list 1 satisfies Tmin+W≤Ti1≤Tmax-W.

[0101] S235: Surf1 is the interface between the nut and the screw.

[0102] Specifically, determine whether the element Ti1 in list 1 satisfies Tmin+W≤Ti≤Tmax-W. When the element Ti1 in list 1 satisfies Tmin+W≤Ti1≤Tmax-W, then Surf1 is the interface between the nut and the screw.

[0103] S236: Set the T-axis coordinate of the split interface to Tsplit.

[0104] S237: Determine whether the element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W.

[0105] Specifically, when element Ti1 in list 1 does not satisfy Tmin+W≤Ti1≤Tmax-W, then it is determined whether element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W.

[0106] S238: Surf2 is the interface between the nut and the screw.

[0107] Specifically, when the element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W, then Surf2 is the interface between the nut and the screw.

[0108] S239: Set the T-axis coordinate of the split interface to Tsplit.

[0109] S240: Reacquire the T-axis coordinates of all modeled feature points on Surf1 and Surf2.

[0110] Specifically, if element Ti2 in list 2 does not satisfy Tmin+W≤Ti2≤Tmax-W, then the T-axis coordinates of all modeling feature points on Surf1 and Surf2 are re-obtained and re-evaluated.

[0111] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and this application can obtain the interface between the nut and the screw through the T-axis.

[0112] Please see Figure 6 , Figure 6 yes Figure 2 The illustrated flowchart shows step S24 in the embodiment shown. In some embodiments, the method includes the following steps:

[0113] S241: Create the centroid of the screw geometry.

[0114] Specifically, the centroid of the screw geometric model entity is created through an algorithm.

[0115] S242: Get the coordinates Tmass on the centroid T-axis.

[0116] Please see Figure 7 , Figure 7 yes Figure 2 The illustrated embodiment shows a flowchart of step S25. In some embodiments, the method includes the following steps:

[0117] S251: Divide the screw geometry along a plane perpendicular to the T-axis through the centroid to obtain two geometric sub-models.

[0118] Specifically, the centroid of the screw geometric model entity is created, and the coordinates Tmass on the T-axis of the centroid are obtained. The screw geometric model entity is then horizontally divided at the centroid perpendicular to the T-axis, with the cut surface being a section of the screw perpendicular to the T-axis, resulting in the first geometric entity sub-model and the second geometric entity sub-model.

[0119] S252: Get the maximum external dimensions of two geometric entity sub-models.

[0120] Specifically, by obtaining the maximum external dimensions of the first and second geometric sub-models, the diameters of the two geometric sub-models can be obtained. Because the screws are assembled with their length direction parallel to the T-axis, and the screw head and shank are perpendicular (both are cylindrical), and the top and bottom surfaces of the screw are circular, the maximum external dimensions of the screw can be obtained through the T-axis and the U-axis (which is parallel to the U-axis). Since the screw is assembled parallel to the T-axis, and the U-axis is perpendicular to the T-axis, and the screw head is perpendicular to the shank (meaning both the top and bottom surfaces of the head are parallel to the U-axis), when the screw geometric model is laterally divided at its centroid perpendicular to the T-axis, the cut surface (i.e., the section of the shank perpendicular to the T-axis) is parallel to the U-axis. Therefore, the minimum coordinate Umin and maximum coordinate Umax of the first and second geometric sub-models on the U-axis can be obtained respectively. Subtracting Umin from Umax yields the maximum diameters of the first and second geometric sub-models.

[0121] S253: Calculate the screw diameter R2.

[0122] Specifically, if the maximum diameters of the first and second geometric entity sub-models are arranged from smallest to largest, the minimum value is the screw diameter R2.

[0123] Understandably, in some embodiments, the screw geometric model entity can be divided into two geometric sub-models at the centroid perpendicular to the T-axis. The maximum external dimensions of the two geometric sub-models are obtained respectively. First, the geometric sub-model with the largest external dimension (maximum diameter) among the first and second geometric sub-models is excluded. Then, the maximum external dimension of the other geometric sub-model is obtained, that is, the minimum coordinate Umin and the maximum coordinate Umax of the geometric sub-model on the U-axis are obtained. Umax-Umin can be used to obtain the screw diameter R2.

[0124] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and the U-axis of this application is the axis perpendicular to the X-axis, Y-axis, Z-axis or any axis. This application can obtain the diameter R2 of the screw in the screw geometry model through the T-axis and U-axis.

[0125] Please see Figure 8 , Figure 8 yes Figure 1 The illustrated embodiment shows a flowchart of step S30. In some embodiments, the method includes the following steps:

[0126] S31: Obtain the T-axis coordinates of the centroid Tmass and the T-axis coordinates of the interface Tsplit.

[0127] Specifically, because the product screws are assembled with their length direction parallel to the T-axis, and the screw nut and screw shaft are perpendicular, the centroid of the screw geometric model entity is created through an algorithm, and the coordinates Tmass on the T-axis of the centroid are obtained.

[0128] Specifically, because the product screws are assembled with their length direction parallel to the T-axis, and the screw nut and shank are perpendicular, with the nut being a cylinder and both its upper and lower faces Surf1 and Surf2 being circular, the T-axis coordinates of all modeling feature points on Surf1 and Surf2 can be obtained via the T-axis. These T-axis coordinates are then stored in empty list 1 and empty list 2, respectively. A tolerance W is set, and it is determined whether the element Ti1 in list 1 satisfies Tmin+W≤Ti≤Tmax-W. When the element Ti1 in list 1 satisfies Tmin+W≤Ti1≤Tmax-W, then Surf1 is the interface between the nut and shank, and the T-axis coordinate of the interface is set to Tsplit. If element Ti1 in list 1 does not satisfy Tmin+W≤Ti1≤Tmax-W, then determine whether element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W. If element Ti2 in list 2 satisfies Tmin+W≤Ti2≤Tmax-W, then Surf2 is the interface between the nut and the screw, and the T-axis coordinate of the interface is set to Tsplit.

[0129] It is understood that in some embodiments, the T-axis can be the X-axis, Y-axis, Z-axis or any axis, and this application can obtain the interface between the nut and the screw through the T-axis.

[0130] S32: Determine if Tmass is greater than Tsplit.

[0131] Specifically, determine whether Tmass is greater than Tsplit or less than Tsplit.

[0132] S33: No, then the nut is on top and the screw is on the bottom (i.e., the nut is on the side with the larger T value and the screw is on the side with the smaller T value).

[0133] Specifically, determine the size of Tmass and Tsplit. If Tmass is less than Tsplit, then the nut is on top and the screw is on the bottom (i.e., the nut is on the side with the larger T value, and the screw is towards the side with the smaller T value). S34: If yes, then the nut is on the bottom and the screw is on the top (i.e., the nut is on the side with the smaller T value, and the screw is towards the side with the larger T value).

[0134] Specifically, determine the size of Tmass and Tsplit. If Tmass is greater than Tsplit, then the nut is at the bottom and the screw is at the top (i.e., the nut is on the side with the smaller T value and the screw is on the side with the larger T value).

[0135] Please see Figure 9 , Figure 9 yes Figure 1 The illustrated embodiment shows a flowchart of step S40. In some embodiments, the method includes the following steps:

[0136] S401: Create a circle at the Tsplit point parallel to the T axis with a diameter equal to the nut diameter R, and obtain the geometric number ID1 of the circle.

[0137] Specifically, in order to establish grid auxiliary lines, first create a circle with a diameter equal to the nut diameter R at the point passing through the Tsplit point and parallel to the T axis, and obtain the geometric number ID1 of the circle.

[0138] S402: Set a tolerance variable w, create a circle with a diameter equal to Rw parallel to the T axis at the Tsplit point, and obtain the geometric number ID2 of the circle.

[0139] Specifically, a tolerance variable w is set, and a circle with a diameter equal to Rw is created at the Tsplit point and parallel to the T axis, and the geometric number ID2 of the circle is obtained. The tolerance w represents the reduced size of the screw. If the mesh is built according to the actual diameter of the screw, there will be interference between the screw mesh and the parts that it mates with. At this time, the screw mesh size needs to be scaled to a certain extent to ensure that the set screw matches the parts that it mates with better.

[0140] S403: Create a new circle at the Tsplit point, parallel to the T axis, in the middle of the annulus formed by the two circles ID1 and ID2, and obtain the geometric number ID3 of the new circle.

[0141] Specifically, at the point passing through Tsplit and parallel to the T-axis, and in the middle of the annulus formed by the two circles ID1 and ID2, create another circle and obtain the geometric number ID3 of that circle.

[0142] S404: Create a circle with a diameter smaller than the screw diameter at the Tsplit point parallel to the T axis, and obtain the geometric number ID4 of the circle.

[0143] Specifically, at the point passing through Tsplit and parallel to the T-axis, create a circle with a diameter smaller than the screw diameter, and obtain the geometric number ID4 of this circle.

[0144] S405: Create 8 temporary nodes equally on the four circles ID1, ID2, ID3 and ID4, and obtain the number of each node.

[0145] Specifically, create 8 temporary nodes equally on each of the four circles ID1, ID2, ID3 and ID4, and obtain the number of each node. The method of division is as follows: calculate the circumference of each circle by its diameter, and divide the circumference by 8 to create 8 temporary nodes equally on each circle.

[0146] Please see Figure 10 , Figure 10 yes Figure 1 The illustrated embodiment shows a flowchart of step S50. In some embodiments, the method includes the following steps:

[0147] S501: Select two nodes on the outermost circle ID1, and select two corresponding nodes on the second circle ID3 to create a quadrilateral mesh.

[0148] Specifically, after creating eight temporary nodes on the four circles ID1, ID2, ID3 and ID4 respectively, two nodes are selected on the outermost circle ID1, and two corresponding nodes are selected on the second circle ID3 to create a quadrilateral mesh.

[0149] S502: Following the method in step S501, create the outermost 8 quadrilateral meshes using the nodes on the two circles ID1 and ID3.

[0150] S503: Following the method in step S501, create quadrilateral meshes sequentially from the nodes on the two circles ID3 and ID2, and the nodes on the two circles ID2 and ID4.

[0151] Specifically, following the method for constructing the outermost quadrilateral mesh, the second and third quadrilateral meshes are created sequentially from the outside in, using the nodes on the two circles ID3 and ID2, and the nodes on the two circles ID2 and ID4.

[0152] S504: The quadrilateral mesh formed by the nodes on ID1 and ID3, ID3 and ID2, and ID2 and ID4 is numbered IDall.

[0153] S505: Connect the nodes on circle ID4 to the center point to create a triangular mesh, numbered Idin.

[0154] Specifically, connect the nodes on circle ID4 to the center point to create a triangular mesh (this triangular mesh can also be described as a quadrilateral mesh; when described as a quadrilateral mesh, two points of the quadrilateral overlap, and the length of one side of the quadrilateral is 0). The created triangular mesh is numbered Idin.

[0155] A two-dimensional mesh model of the screw was constructed.

[0156] Please see Figure 11 , Figure 11yes Figure 1 The illustrated embodiment shows a flowchart of step S60. In some embodiments, the method includes the following steps:

[0157] S601: Select all quadrilateral grids numbered IDall, and stretch them upwards or downwards to form a screw-nut grid.

[0158] Specifically, select all the quadrilateral meshes numbered IDall, and stretch them upwards or downwards by a distance of H, along with the thickness value H of the nut, to create the 3D mesh of the nut.

[0159] S602: Select all triangular meshes numbered Idin, as well as quadrilateral meshes formed by nodes on ID2 and ID4.

[0160] Specifically, select all triangular meshes numbered Idin (this triangular mesh can also be described as a quadrilateral mesh; when described as a quadrilateral mesh, two points of the quadrilateral overlap and one side of the quadrilateral has a length of 0), as well as the quadrilateral mesh formed by the nodes on ID2 and ID4, to prepare for stretching to form a screw network.

[0161] S603: Stretch downwards or upwards into a screw mesh.

[0162] Specifically, in conjunction with the length value of the screw, which can be calculated from the length L of the screw and the thickness H of the nut, i.e., screw length = LH, after selecting the two-dimensional mesh of the screw, stretching it downward or upward to a distance of LH will obtain the three-dimensional mesh of the screw; the three-dimensional mesh of the nut and the three-dimensional mesh of the screw are completed, thus completing the three-dimensional mesh model of the screw.

[0163] Please see Figure 12 , Figure 12 This is a schematic flowchart of another embodiment of the method for establishing a screw finite element model according to this application. In some embodiments, the method includes the following steps:

[0164] S10': Import the screw geometry model into the modeling software.

[0165] Specifically, the screw geometry model is imported into the Hypermesh modeling software.

[0166] S21': Obtain the screw length L and nut diameter R.

[0167] Specifically, in the assembly, the length direction of the screw's geometric model is parallel to the Z-axis. The screw nut is perpendicular to the screw shaft, and the nut is cylindrical with both its top and bottom surfaces being circular. Therefore, in the coordinate system, the maximum geometric dimensions of the screw can be obtained through the Z-axis and the X-axis (which is perpendicular to the Z-axis and parallel to the X-axis on both sides of the nut). This allows us to obtain the screw's length L and the nut's diameter R. The algorithm obtains the screw's minimum coordinate Z1 and maximum coordinate Z2 on the Z-axis. Therefore, Z2 and Z1 give the screw's length L, i.e., L = Z2 - Z1. Simultaneously, since the X-axis is perpendicular to the Z-axis, and the screw nut is perpendicular to the screw shaft, with both its top and bottom surfaces parallel to the X-axis, we can obtain the nut's minimum coordinate X1 and maximum coordinate X2 on the X-axis. From X1 and X2, we can obtain the nut's diameter R, i.e., R = X2 - X1.

[0168] Understandably, there is also a Y-axis that is perpendicular to the X-axis and the Z-axis. By obtaining the minimum coordinate Y1 of the nut on the Y-axis and the maximum coordinate Y2 of the nut on the Y-axis, the diameter R of the nut can also be obtained from Y1 and Y2, that is, R = Y2 - Y1 (because the nut is a cylinder, X2 - X1 = Y2 - Y1, therefore, R can be calculated from either the X-axis or the Y-axis).

[0169] S22': Take the thickness value of the nut.

[0170] Specifically, in the Hypermesh software, a for loop iterates through the screw geometry model, extracting all its geometric surfaces and calculating the area of ​​each surface. The areas are then sorted to extract the IDs (similar to physical addresses) of the two largest and second-largest surfaces in the screw geometry model. These IDs are represented by variables Surf1 and Surf2, which are the top and bottom surfaces of the nut. Since the screw is assembled parallel to the Z-axis, and the nut is perpendicular to the screw shaft, and the nut is cylindrical, with both Surf1 and Surf2 being circular, the Z-axis coordinates of the screw geometry Surf1 and Surf2 can be obtained. Obtain the coordinates Z3 and Z4 of the Surf1 surface on the Z-axis (Z3 = Z4 in the case of a plane, Z3 is not equal to Z4 in the case of a curved surface), and then obtain the coordinates Z5 and Z6 of the Surf2 surface on the Z-axis (Z5 = Z6 in the case of a plane, Z5 is not equal to Z6 in the case of a curved surface). Construct list 3, i.e., List3 = [Z3, Z4, Z5, Z6]. Sort the list elements in descending order, and subtract the minimum value from the maximum value in the list. The result is the nut thickness value H.

[0171] S23': Obtain the Z-axis coordinate of the interface between the nut and the screw in the screw.

[0172] Specifically, because the product screws are assembled with their length direction parallel to the Z-axis, and the screw nut and shank are perpendicular, with the nut being a cylinder and both its upper and lower faces Surf1 and Surf2 being circular, the Z-axis coordinates of all modeling feature points on Surf1 and Surf2 can be obtained via the Z-axis. These Z-axis coordinates are then stored in empty lists 4 and 5, respectively. A tolerance W is set, and the element Zi1 in list 4 is checked to see if it satisfies Zmin + W ≤ Zi ≤ Zmax - W. If Zi1 satisfies Zmin + W ≤ Zi1 ≤ Zmax - W, then Surf1 is the interface between the nut and shank, and the Z-axis coordinate of this interface is set to Zsplit. If element Zi1 in list 4 does not satisfy Zmin+W≤Zi1≤Zmax-W, then check if element Zi2 in list 5 satisfies Zmin+W≤Zi2≤Zmax-W. If element Zi2 in list 5 satisfies Zmin+W≤Zi2≤Zmax-W, then Surf2 is the interface between the nut and the screw, and the Z-axis coordinate of the interface is set to Zsplit. If element Zi2 in list 5 does not satisfy Zmin+W≤Zi2≤Zmax-W, then re-obtain the Z-axis coordinates of all modeling feature points on Surf1 and Surf2, and re-check.

[0173] S24': Get the coordinates Zmass of the centroid of the screw entity.

[0174] Specifically, because the product screws are assembled with their length direction parallel to the Z-axis, and the screw nut and screw shaft are perpendicular, the centroid of the screw geometric model entity is created through an algorithm, and the coordinates Zmass on the Z-axis of the centroid are obtained.

[0175] S25': Obtain the screw diameter.

[0176] Specifically, because the product screws are assembled with their length direction parallel to the Z-axis, the screw nut and screw rod are perpendicular, the nut is a cylinder, the screw rod is also a cylinder, and both the top and bottom surfaces of the nut are circular, in the coordinate system, the maximum geometric coordinate dimensions of the screw can be obtained through the Z-axis and the X-axis set perpendicular to the Z-axis (while the nut is parallel to the U-axis). The screw is assembled parallel to the Z-axis. Since the X-axis is set perpendicular to the Z-axis, and the screw nut is perpendicular to the screw shaft (meaning the top and bottom faces of the nut are parallel to the X-axis), when the screw geometric model is laterally divided at its centroid perpendicular to the Z-axis to obtain the first and second geometric sub-models, the cross-section (i.e., the section of the screw shaft perpendicular to the Z-axis) is parallel to the X-axis. Therefore, the minimum coordinate Xmin and maximum coordinate Xmax of the first and second geometric sub-models on the X-axis can be obtained respectively. Xmax - Xmin gives the maximum diameter of the first and second geometric sub-models. Arranging the maximum diameters of the first and second geometric sub-models from smallest to largest, the minimum value is the screw diameter R2.

[0177] S30': Determine the orientation of the screw.

[0178] Specifically, the coordinates Zsplit of the Z-axis at the interface between the nut and the screw obtained in step S23' and the centroid coordinates Zmass of the screw entity obtained in step S24' are used to determine the size of Zmass and Zsplit. If Zmass is less than Zsplit, the nut is on top and the screw is on the bottom (i.e., the nut is on the side with the larger Z value and the screw is on the side with the smaller Z value). If Zmass is greater than Zsplit, the nut is on the bottom and the screw is on the top (i.e., the nut is on the side with the smaller Z value and the screw is on the side with the larger Z value).

[0179] S40': Establish grid auxiliary lines using geometric dimensions and coordinate information.

[0180] Specifically, to establish the mesh auxiliary lines, first, at the Z-split point and parallel to the Z-axis, create a circle with a diameter equal to the nut diameter R, and obtain its geometric number ID1. Then, set a tolerance variable w, and at the Z-split point and parallel to the Z-axis, create a circle with a diameter equal to Rw, and obtain its geometric number ID2. The tolerance w represents the reduced screw size, because if the mesh is built according to the actual screw diameter, there will be interference between the screw mesh and the mating parts. In this case, the screw mesh size needs to be scaled to ensure that the set screw better matches the mating parts. Next, at the Z-split point and parallel to the Z-axis, create another circle in the middle of the annulus formed by the two circles ID1 and ID2, and obtain its geometric number ID3. Finally, at the Z-split point and parallel to the Z-axis, create a circle with a diameter smaller than the screw diameter, and obtain its geometric number ID4. Finally, create 8 temporary nodes equally on each of the four circles ID1, ID2, ID3, and ID4, and obtain the number of each node. The division method is as follows: calculate the circumference of each circle using its diameter, and divide the circumference by 8 to create 8 temporary nodes equally on each circle. The mesh auxiliary lines are now complete.

[0181] S50': Create a two-dimensional mesh model of the screw.

[0182] Specifically, after creating eight temporary nodes on the four circles ID1, ID2, ID3, and ID4, two nodes are selected on the outermost circle ID1, and two corresponding nodes are selected on the second circle ID3 to create a quadrilateral mesh. Following this method, the outermost eight quadrilateral meshes are created using the nodes on circles ID1 and ID3. Next, quadrilateral meshes are created sequentially using the nodes on circles ID3 and ID2, and circles ID2 and ID4, following the same method, creating the second and third circles of quadrilateral meshes from the outside in. The quadrilateral meshes formed by the nodes on ID1 and ID3, ID3 and ID2, and ID2 and ID4 are then numbered IDall. Finally, the nodes on circle ID4 are connected to the center point to create a triangular mesh (this triangular mesh can also be described as a quadrilateral mesh; when described as a quadrilateral mesh, two points of the quadrilateral overlap, and one side of the quadrilateral has a length of 0). The created triangular mesh is numbered Idin. The screw's two-dimensional mesh model is now complete.

[0183] S60': Create a 3D mesh model of the screw.

[0184] Specifically, first, select all quadrilateral meshes numbered IDall, and stretch them upwards or downwards by a distance H, along with the thickness H of the nut, to create the 3D mesh of the nut. Then, select all triangular meshes numbered Idin (these triangular meshes can also be described as quadrilateral meshes; when described as quadrilateral meshes, two points of the quadrilateral overlap, and one side of the quadrilateral has a length of 0), as well as the quadrilateral mesh formed by the nodes on ID2 and ID4, to prepare for stretching to form the screw mesh. Finally, using the screw length value (calculated from the screw length L and the nut thickness H, i.e., screw length = LH), select the 2D mesh of the screw, and stretch it downwards or upwards by a distance LH to obtain the 3D mesh of the screw. The completion of the 3D meshes of the nut and the screw constitutes the completion of the 3D mesh model of the screw.

[0185] It is understood that in other embodiments, the length direction of the screw geometry model in the assembly may also be parallel to the X-axis, Y-axis, or any axis intersecting the X-axis, Y-axis, or Z-axis. When the length direction of the screw geometry model in the assembly is parallel to the X-axis, Y-axis, or any axis intersecting the X-axis, Y-axis, or Z-axis, the method steps for establishing the screw finite element model are the same as those in this embodiment.

[0186] Please see Figure 13 , Figure 13 This is a schematic diagram of an embodiment of the electronic device of this application, which can be applied to the method for establishing a screw finite element model described above. The electronic device 300 may include a processor 302 and a memory 304. The memory 304 stores a computer program, which, when executed by the processor 302, is used to implement the method for establishing a screw finite element model in any of the above embodiments.

[0187] Specifically, processor 302 controls the operation of electronic device 300. Processor 302 can also be referred to as CPU (Central Processing Unit). Processor 302 may be an integrated circuit chip with signal processing capabilities. Processor 302 can also be a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), off-the-shelf programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component. The general-purpose processor can be a microprocessor or any conventional processor.

[0188] The memory 304 is used to store program data executed by the processor 302 and data generated during the processor 302's processing. The memory 304 may include a non-volatile storage portion for storing the program data. In another embodiment, the memory 304 may serve solely as the processor 302's memory, caching data generated during the processor 302's processing. This program data is actually stored in a device outside the processor 302. The processor 302 connects to this external device and executes corresponding processing by calling the externally stored program data.

[0189] Please see Figure 14 , Figure 14 This is a schematic diagram of a computer-readable storage medium according to an embodiment of the present application. The computer-readable storage medium 400 stores a computer program 402, which, when executed by a processor, implements the above-described method for establishing a screw finite element model.

[0190] It should be noted that the device in this embodiment can perform the steps in the above method. For a detailed description of the relevant content, please refer to the above method section, which will not be repeated here.

[0191] Unlike existing technologies, this application obtains the coordinates of the screw's external geometry in the screw's geometric model, identifies the coordinates of the interface between the nut and the screw and the coordinates of the centroid of the screw entity, determines the screw orientation, and establishes two-dimensional and three-dimensional mesh models of the screw, thereby achieving rapid, batch, and automated creation of screw finite element models.

[0192] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program 402 instructing related hardware. The computer program 402 can be stored in a non-volatile computer-readable storage medium. When executed, the computer program 402 can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0193] In the above embodiments, by obtaining the coordinates of the screw's external geometry in the screw geometric model, identifying the coordinates of the interface between the nut and the screw and the coordinates of the centroid of the screw entity, determining the screw orientation, and establishing two-dimensional and three-dimensional mesh models of the screw, the finite element model of the screw can be established quickly, in batches, and automatically.

[0194] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method of building a finite element model of a screw, characterized by, The method comprises the following steps: Importing a screw geometry model into a modeling software; Obtaining coordinates of a screw contour geometry in the screw geometry model, including: obtaining coordinates of a screw cap and screw rod interface and coordinates of a screw entity center of mass; further including: extracting an ID number Surf1 of a single screw cap upper surface and an ID number Surf2 of a screw cap lower surface, when a screw length direction is parallel to a T axis, obtaining coordinates of all modeling feature points on the Surf1 and the Surf2, first storing coordinates of all modeling feature points of one surface in an empty list, setting a tolerance R, comparing with a screw contour size Tmax and Tmin, when a certain element Ti in the list satisfies Tmin+R≤Ti≤Tmax-R, the Surf1 or the Surf2 is determined to be located at the screw cap and screw rod interface, so that coordinates Tsplit of the interface can be obtained; Judging a screw rod orientation; Establishing a grid auxiliary line by using geometric dimensions and coordinate information; Establishing a screw two-dimensional grid model; Establishing a screw three-dimensional grid model.

2. The method of building a finite element model of a screw of claim 1, wherein, The obtaining of the coordinates of the screw contour geometry in the screw geometry model includes: obtaining coordinates of a screw cap and screw rod interface and coordinates of a screw entity center of mass; further including: Obtaining a screw length L; Obtaining a screw cap diameter R; Obtaining a screw cap thickness value, and obtaining the screw cap thickness value according to the coordinates of the Surf1 and the Surf2.

3. The method of building a finite element model of a screw of claim 2, wherein, The obtaining of the coordinates of the screw contour geometry in the screw geometry model includes: obtaining coordinates of a screw cap and screw rod interface and coordinates of a screw entity center of mass; further including: Obtaining a center of mass coordinate, creating a center of mass of a screw entity, and obtaining a center of mass coordinate Tmass; Obtaining a screw rod diameter R2, and cutting the screw entity at the center of mass to obtain two geometric entity sub-models, and obtaining maximum contour sizes of the two geometric entity sub-models, so as to obtain the screw rod diameter R2.

4. The method of building a finite element model of a screw of claim 3, wherein, The judging of the screw rod orientation includes: Judging sizes of Tmass and Tsplit of the screw, when Tmass is less than Tsplit, the screw cap is upper, and the screw rod is downward; when Tmass is greater than Tsplit, the screw cap is lower, and the screw rod is upward.

5. The method of building a finite element model of a screw of claim 4, wherein, The establishing of the grid auxiliary line by using the geometric dimensions and the coordinate information includes: Creating a circle with a diameter equal to the screw cap diameter R at the Tsplit point parallel to the T axis, and obtaining a geometric number ID1 of the circle; Setting a tolerance r variable, creating a circle with a diameter equal to the screw rod diameter minus the tolerance r at the Tsplit point parallel to the T axis, and obtaining a geometric number ID2 of the circle; Creating a circle between the geometric number ID1 and the geometric number ID2, and obtaining a geometric number ID3 of the circle; Creating a circle with a diameter smaller than the geometric number ID2, and obtaining a geometric number ID4 of the circle.

6. The method of building a finite element model of a screw of claim 5, wherein, The establishing of the screw two-dimensional grid model includes: Equally dividing eight nodes on each of the four circles from inside to outside of the geometric number ID1, the geometric number ID2, the geometric number ID3 and the geometric number ID4, and obtaining coordinates of each node; First, from the outermost circle of the geometric number ID1 and the second circle of the geometric number ID3 circle node, in order to select the geometric number ID1 2 nodes and the corresponding 2 nodes of the geometric number ID3, create a quadrilateral mesh, other nodes according to this method, that is, the outer circle of the 8 quadrilateral mesh can be generated; Then from the second circle of the geometric number ID3 to the third circle of the geometric number ID2, the third circle of the geometric number ID2 to the fourth circle of the geometric number ID4, the fourth circle of the geometric number ID4 to the center point in turn, the nodes are connected to create a quadrilateral mesh.

7. The method of building a finite element model of a screw of claim 6, wherein, The establishment of the screw three-dimensional grid model comprises: First, stretch the nut grid, that is, through the outermost circle of the geometric number ID1, the second circle of the geometric number ID3, the third circle of the geometric number ID2, the innermost circle of the geometric number ID4 and the center point of the grid created upwards or downwards to generate the nut grid; Then stretch the screw rod grid, and then generate the screw rod grid by stretching the third circle of the geometric number ID2, the innermost circle of the geometric number ID4 and the center point of the grid downwards or upwards.

8. The method of building a finite element model of a screw of claim 7, wherein, When the length direction of the screw is parallel to the T axis, the coordinates of all modeling feature points on Surf1 and Surf2 are obtained, comprising: When the length direction of the screw is parallel to the X axis, the coordinates of all modeling feature points on Surf1 and Surf2 are obtained; or, When the length direction of the screw is parallel to the Y axis, the coordinates of all modeling feature points on Surf1 and Surf2 are obtained; or, When the length direction of the screw is parallel to the Z axis, the coordinates of all modeling feature points on Surf1 and Surf2 are obtained; or, When the length direction of the screw is parallel to any axis intersecting with the X axis, the Y axis or the Z axis, the coordinates of all modeling feature points on Surf1 and Surf2 are obtained.

9. An electronic device, comprising: The memory and the processor are connected to each other, wherein the memory stores a computer program, and the computer program is used to implement the steps of the method for establishing a screw finite element model according to any one of claims 1-8 when executed by the processor.

10. A computer-readable storage medium, characterized in that, The computer program is stored thereon and is executed to implement the method for establishing a screw finite element model according to any one of claims 1-8.

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