Wire cold bending crack resistance evaluation method and device, electronic equipment and storage medium

Abstract

The invention relates to the technical field of material analysis, and discloses a wire cold bending crack resistance evaluation method and device, electronic equipment and a storage medium, and the method comprises the steps: obtaining the radial stress and shear stress of a preset test point under each bending degree when a target wire is subjected to symmetric cold bending according to different bending degrees, determining the key bending degree based on the shear stress, and determining the bending degree of the target wire according to the key bending degree; determining a shear stress influence factor according to the shear stress corresponding to the key bending degree, determining a radial stress influence factor according to the radial stress corresponding to the initial bending degree, the tail end bending degree and the later bending degree, and determining cold bending crack resistance parameters of the target wire according to the shear stress influence factor and the radial stress influence factor. The method can break through the limitation that the existing standard only judges whether the crack exists or not, realizes full-dimension quantitative evaluation of the crack initiation tendency, the expansion direction and the expansion rate of the wire material, covers the core key index of the cold bending crack resistance, and improves the accuracy of wire material quality evaluation.

Description

Technical Field

[0001] This invention relates to the field of materials analysis technology, specifically to a method, apparatus, electronic device, and storage medium for evaluating the cold bending crack resistance of wire. Background Technology

[0002] The applications of drawn wire are very wide. For example, steel wire, with its combination of high strength and good flexibility, is one of the key materials in industries such as aerospace, long-span bridges, and nuclear industry; tungsten wire is an important material for making filaments for various lighting lamps, cathode ray tube filaments, vapor-deposited heat exchangers, thermocouples, electrodes and contact devices, high-temperature heating elements, etc. Therefore, quality control of wire is very important.

[0003] Existing industry and national standards specify various performance indicators for monitoring the quality of tungsten wires. For example, the crack resistance of tungsten wires of different diameters and for different applications is tested using the "winding method," "bending method," and "push-pull method," with the presence or absence of cracks as the evaluation criterion. However, these methods still have limitations for material research and development. First, the operation is relatively rough, easily leading to uneven force and inaccurate results. Second, judging the plastic deformation capacity of the wire based on the presence or absence of cracks results in insufficiently precise quality classification, failing to provide more detailed guidance for adjusting process parameters. These limitations prevent accurate evaluation of tungsten wire quality. Summary of the Invention

[0004] This invention provides a method, apparatus, electronic device, and storage medium for evaluating the cold bending crack resistance of wire materials, in order to solve the problem of the inability to accurately evaluate the quality of wire materials.

[0005] In a first aspect, the present invention provides a method for evaluating the cold bending crack resistance of a wire, the method comprising: when a target wire is symmetrically cold-bent with the vertical line of the tangential direction of a preset test point as the axis of symmetry, and at different curvatures, obtaining the radial stress and shear stress at the preset test point at each curvature; determining the initial curvature, end curvature, and later curvature of the target wire based on each curvature and shear stress; determining the shear stress influence factor according to the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature; determining the radial stress influence factor according to the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature; and determining the cold bending crack resistance parameters of the target wire according to the shear stress influence factor and the radial stress influence factor, wherein the cold bending crack resistance parameters are used to evaluate the cold bending crack resistance of the target wire.

[0006] The present invention provides a method for evaluating the cold bending crack resistance performance of wire. By symmetrically cold bending the target wire at different curvatures, the radial stress and shear stress at preset test points are obtained at each curvature. Based on the shear stress, the initial curvature, end curvature, and later curvature are determined. The shear stress influence factor is determined based on the shear stress corresponding to the initial curvature, end curvature, and later curvature. Similarly, the radial stress influence factor is determined based on the radial stress corresponding to the initial curvature, end curvature, and later curvature. This allows for the determination of the cold bending crack resistance performance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. This method overcomes the limitation of existing standards that only determine the presence or absence of cracks, achieving a comprehensive quantitative evaluation of the crack initiation tendency, propagation direction, and propagation rate of the wire. It covers the core key indicators of cold bending crack resistance performance and improves the accuracy of wire quality evaluation.

[0007] In one optional implementation, determining the initial curvature, end curvature, and later curvature of the target filament based on various curvatures and shear stresses includes: sorting the curvatures from smallest to largest and recording the shear stresses corresponding to each curvature after sorting; based on each shear stress, finding the first shear stress that first exceeds a preset threshold and using the curvature corresponding to the first shear stress as the initial curvature; based on each shear stress, finding the largest second shear stress and using the curvature corresponding to the second shear stress as the end curvature; based on each shear stress, finding the third shear stress that first decreases after the second shear stress and using the curvature corresponding to the third shear stress as the later curvature.

[0008] This invention determines the critical curvature based on shear stress, transforming the determination of critical curvature from subjective trend judgment to objective numerical screening, reducing human error and improving the consistency of evaluation results. At the same time, it directly links shear stress changes with plastic deformation stages, making critical curvature a quantitative marker for the division of plastic deformation stages, providing a clear stage division basis for subsequent stress influence factor calculations.

[0009] In one optional embodiment, determining the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature includes: using the absolute value of the first shear stress corresponding to the initial curvature as the first shear stress influence factor, the absolute value of the second shear stress corresponding to the end curvature as the second shear stress influence factor, and the absolute value of the third shear stress corresponding to the later curvature as the third shear stress influence factor; calculating a first difference between the absolute value of the second shear stress and the absolute value of the first shear stress, and using the ratio between the first difference and the absolute value of the second shear stress as the fourth shear stress influence factor; calculating a second difference between the absolute value of the second shear stress and the absolute value of the third shear stress, and using the ratio between the second difference and the absolute value of the second shear stress as the fifth shear stress influence factor.

[0010] This invention constructs a two-dimensional shear stress influence factor system based on the absolute value of the basic shear stress and the rate of stress change. This system can reflect the stress state of the wire at different stages of plastic deformation and quantify the stress change trend. It can comprehensively characterize the toughness of crack initiation and early propagation, and provide a direct basis for the quantitative classification of wire toughness.

[0011] In one optional embodiment, the radial stress influence factor is determined based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature, including: using the absolute value of the first radial stress corresponding to the initial curvature as the first radial stress influence factor, the absolute value of the second radial stress corresponding to the end curvature as the second radial stress influence factor, the absolute value of the third radial stress corresponding to the later curvature as the third radial stress influence factor; and using the absolute value of the sum of the second and third radial stresses as the fourth radial stress influence factor.

[0012] This invention incorporates radial stress into the core influencing factors of wire quality evaluation, reflecting the radial stress state at different stages and accurately capturing the overall change in radial stress caused by crack propagation. This addresses the difficulty of existing methods in determining the degree and tendency of crack propagation, providing core support for subsequent differentiated evaluation of crack resistance. Furthermore, the radial stress influencing factor complements the shear stress influencing factor, jointly constructing a stress characterization system for the degree and tendency of crack propagation from initiation to propagation.

[0013] In one optional implementation, the cold bending crack resistance parameters of the target wire are determined based on the shear stress influence factor and the radial stress influence factor, including: using the ratio of the second shear stress influence factor to the fourth radial stress influence factor as the first cold bending crack resistance performance evaluation index, the first cold bending crack resistance performance evaluation index characterizing the axial cold bending crack resistance performance of the target wire; and using the ratio of the fifth shear stress influence factor to the second radial stress influence factor as the second cold bending crack resistance performance evaluation index, the second cold bending crack resistance performance evaluation index characterizing the radial cold bending crack resistance performance of the target wire.

[0014] This invention constructs two evaluation indicators for cold bending crack resistance, which can quantify the axial crack propagation tendency and radial crack propagation rate respectively, realizing differentiated evaluation of crack resistance performance and breaking through the current limitation of only judging the qualitative cold bending performance by judging the presence or absence of cracks. At the same time, it takes into account the synergistic evaluation of toughness and crack resistance performance. Toughness can be determined by the shear stress influence factor, and the radial stress influence factor can be used to assist in judging the degree and direction of crack propagation during cold bending, thus realizing comprehensive performance characterization.

[0015] In one optional embodiment, after selecting a first wire and a second wire within a range where the wire diameter is greater than or equal to a first threshold and less than or equal to a second threshold, and determining the corresponding cold bending crack resistance performance parameters, the method further includes: comparing the first cold bending crack resistance performance evaluation index of the first wire and the second wire, and comparing the second cold bending crack resistance performance evaluation index of the first wire and the second wire to obtain an evaluation result. In the evaluation result, if the first cold bending crack resistance performance evaluation index is larger and the second cold bending crack resistance performance evaluation index is smaller, the cold bending crack resistance performance of the corresponding wire is relatively better.

[0016] This invention, by directly linking evaluation parameters with crack resistance performance, can clearly define the rules for comparing the crack resistance performance of wires of the same specification but different materials. It does not require the introduction of additional complex indicators, is simple and efficient to operate, and can quickly determine the differences in crack resistance performance of wires of the same specification but different materials, thus meeting the actual needs of screening multi-specification and multi-material wires in industrial production.

[0017] In one optional implementation, the target filament is fixed to the mold with different curvatures. When symmetrically cold-bending is performed according to different curvatures, the radial stress and shear stress at preset test points under each curvature are obtained. This includes: adjusting the height of the mold to the original height so that the laser positioning spot of the X-ray diffractometer is within the diameter range of the target filament, and determining the height fluctuation value according to the radius of the target filament. Using the original height as a reference, a first upward floating height and a second downward floating height are determined according to the height fluctuation value. For any curvature, the X-ray diffractometer is controlled to measure the preset test points according to the original height, the first height, and the second height, respectively, to obtain multiple radial stress measurement values ​​and multiple shear stress measurement values. The radial stress is obtained by averaging the multiple radial stress measurement values, and the shear stress is obtained by averaging the multiple shear stress measurement values.

[0018] This invention combines three-height gradient testing, which can effectively offset errors such as height positioning ambiguity and uneven transmission depth caused by the curved surface of thin-diameter wires, improve the accuracy of conventional XRD testing for characterizing curved surface samples, and thus enhance the repeatability and stability of stress data, providing a reliable data basis for curvature determination and factor calculation.

[0019] Secondly, the present invention provides a device for evaluating the cold bending crack resistance performance of wire. The device includes: a stress measurement module, used to acquire the radial stress and shear stress at each preset test point under different curvatures when the target wire is symmetrically cold-bent with the vertical line of the tangential direction of the preset test point as the axis of symmetry; a curvature determination module, used to determine the initial curvature, end curvature, and later curvature of the target wire based on each curvature and shear stress; a first factor determination module, used to determine the shear stress influence factor according to the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature; a second factor determination module, used to determine the radial stress influence factor according to the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature; and a crack resistance evaluation module, used to determine the cold bending crack resistance performance parameters of the target wire according to the shear stress influence factor and the radial stress influence factor, wherein the cold bending crack resistance performance parameters are used to evaluate the cold bending crack resistance performance of the target wire.

[0020] Thirdly, the present invention provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the method for evaluating the cold bending crack resistance of wire as described in the first aspect or any corresponding embodiment.

[0021] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the method for evaluating the cold bending crack resistance of wire as described in the first aspect or any corresponding embodiment.

[0022] Fifthly, the present invention provides a computer program product, including computer instructions, which are used to cause a computer to execute the method for evaluating the cold bending crack resistance of wire as described in the first aspect or any corresponding embodiment. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the first process of the method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a mold for evaluating the cold bending crack resistance performance of wire according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the second process of the method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention; Figure 4 This is a schematic SEM image of an A3 sample of the wire cold bending crack resistance evaluation method according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the third process of the method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention; Figure 6 This is a schematic diagram of wire fixing in the method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention; Figure 7 This is a schematic diagram of crack propagation in a method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention. Figure 8 This is a schematic diagram of crack propagation in wires with different degrees of curvature according to the method for evaluating the cold bending crack resistance of wires according to an embodiment of the present invention. Figure 9 This is a structural block diagram of a wire cold bending crack resistance evaluation device according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] According to an embodiment of the present invention, an embodiment of a method for evaluating the cold bending crack resistance performance of wire is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0029] This embodiment provides a method for evaluating the cold bending crack resistance of wire, which can be used in terminal devices such as computers. Figure 1 This is a flowchart of a method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention, such as... Figure 1 As shown, the process includes the following steps: Step S101: When the target wire is symmetrically cold-bent with the vertical line of the tangential direction of the preset test point as the axis of symmetry, and is successively subjected to different degrees of curvature, the radial stress and shear stress of the preset test point under each degree of curvature are obtained.

[0030] Specifically, in this embodiment of the invention, cold bending is a processing technology in which metal is plastically bent and deformed at room temperature (without heating) by applying external force through a mold or machinery, forming a specific cross-sectional shape (such as angle steel, channel steel, or bent parts). Wire cold bending is a processing technology in which external force is applied to metal wires (such as steel wire, aluminum wire, copper wire, etc.) at room temperature, causing them to plastically bend and deform, forming the desired curve or angle (such as U-shape, ring, or wave shape).

[0031] During cold bending, as the external force increases, the wire first enters the elastic deformation stage, where the stress increases; then it enters the plastic deformation stage, where the internal mechanism of "work hardening" dominates, and the stress continues to increase; in the later stage of plastic deformation, the internal mechanism of the wire shifts from "work hardening" to "damage accumulation" or "softening mechanism," causing microcracks to continue to propagate, stress to be released, and the stress begins to decrease. Therefore, the degree of crack propagation inside and outside the wire during the above process, based on the quantitatively applied external force, can be used to evaluate the cold bending crack resistance of the wire.

[0032] Furthermore, the crack propagation process in wire is as follows: When an external force is applied, under the combined action of stress and material defects, the crack starts from the initiation site and gradually extends along the path of least resistance, eventually leading to fracture. Therefore, the factors affecting crack propagation are the form and magnitude of the applied external force, and the defects in the material itself. For example, driving forces in different directions will cause different fracture modes in the wire. Among them, shear stress is the main driving force for plastic deformation, causing ductile fracture; normal stress usually causes elastic deformation, which easily leads to brittle fracture. Therefore, this can be used to evaluate the material's plastic deformation capacity or toughness and other related indicators. Material defects, such as inclusions, pores, and weak grain boundaries formed during smelting or processing, or surface scratches caused by external forces, local extrusion during winding, etc., all affect the crack propagation path.

[0033] During cold bending, cracks in the wire mainly propagate along a combined radial and axial path. Therefore, this invention selects specific directions of the wire for testing to obtain stress in different directions, and determines the changes in the plastic deformation mechanism during cold bending based on the stress change trend, i.e., when different plastic deformation stages are entered and is marked with the corresponding curvature of each stage; then, the main crack propagation direction is determined by the stress change trend before and after the curvature, and the degree of crack propagation is quantified using stress values.

[0034] During cold bending of wire, the tensile stress on the outer side of the wire diameter is the main driving force for crack initiation. According to fracture mechanics, cracks usually preferentially propagate in the direction of maximum tensile stress; therefore, cracks preferentially propagate perpendicular to the axis (radial). Since shear stress is perpendicular to the plane to be measured and tangent to the outer side of the wire diameter circumference, it is most sensitive to the change. Therefore, shear stress can be used to determine the specific curvature corresponding to the change in deformation mechanism during the cold bending plastic deformation of the wire, and relevant quantitative indicators can be established using stress values.

[0035] The propagation path of a crack is determined by the material's anisotropy, microstructure, and defect state. For example: ① During the drawing or forging process, wires form a fibrous grain structure (axial grain elongation). If the crack is to continue propagating perpendicularly to the axis (radial), it needs to cross more grain boundaries, resulting in greater resistance to crack propagation. If the grains are highly oriented axially (such as in tungsten wires after multiple drawing passes), the crack is more likely to propagate axially along grain boundaries or weak bonding surfaces (such as inclusions or carbide agglomeration areas). ② Surface defects in the wire, such as scratches, folds, or decarburized layers, can become crack initiations and also affect the crack propagation direction. For example, transverse scratches may propagate into radial cracks during cold bending. ③ Annealing can eliminate residual stress and refine grains, reducing anisotropy, making the crack direction more radial. ④ Adding elements, such as doping tungsten with K, Al, or Si, can improve grain boundary bonding, suppress axial cracks, and make the crack direction more radial. The combined effect of the above factors is reflected in plane stress, which will cause the test results of the test area to change significantly as the crack propagates.

[0036] The variation of radial stress in plane stress is more complex. When the wire is placed horizontally, the test results of the test area are simultaneously affected by the tensile stress on the outside and the compressive stress on the inside (bending causes the outer material to be stretched and the inner material to be compressed). As the crack propagates, the radial stress may change from tensile stress to compressive stress, which is beneficial for differentiated characterization. Therefore, radial stress can be used to help evaluate the degree of crack propagation under different degrees of bending.

[0037] In summary, cracks initiate during cold bending and preferentially propagate perpendicular to the axis (radial). At this stage, shear stress is the first to be affected, and this shear stress can be used to establish a specific degree of curvature and related quantitative indicators. If the crack continues to propagate and extends into the test area, the radial stress will also change significantly, even altering its trend, and related quantitative indicators can also be established. By comparing the tangential and radial stresses of wires of the same diameter but processed using different methods, the tendency direction of crack propagation can be determined, the degree of crack propagation can be quantified, and it can be determined which factor has a greater influence on crack propagation, facilitating the adjustment of process parameters.

[0038] Therefore, the embodiments of the present invention are based on a diameter of 0.038±0.003mm≤ φ A drawn tungsten wire ≤2±0.03mm was used as the target wire for the sample. The target wire was symmetrically cold-bent according to different curvatures to obtain the radial stress and shear stress at preset test points in the target wire at various curvatures during the cold bending process. When the target wire is subjected to external force, it is in a three-dimensional stress state, which can be decomposed along three directions: radial, axial, and circumferential (tangential). In this embodiment of the invention, the relationship between the sample coordinate system and the experimental coordinate system in the X-ray Diffraction Residual Stress Measurement Method (XRD) is defined as follows: when the horizontal rotation angle φ of the laboratory coordinate system is 0°, the axial direction of the drawn wire is the same as the X-ray diffraction path direction; therefore, the plane stress measured at this time is... For the radial stress of the wire, This represents the corresponding shear stress. Due to the limited X-ray transmission depth, generally not exceeding 10 μm, the measured stress is the surface stress. However, because the wire diameter is small, applying a small external force can cause a corresponding change in its stress, and the conventional X-ray transmission depth is relatively sufficient. Therefore, the test results can reflect the overall trend of stress change in the wire to a certain extent.

[0039] Furthermore, the following methods can be used during testing: Figure 2The mold shown has grooves of different curvatures. The target filament is fixed within a groove (dashed line) and a preset test point (solid dot) is exposed. Using the perpendicular line to the tangential direction of the preset test point as the axis of symmetry, different grooves correspond to different degrees of curvature, and different degrees of curvature correspond to different external forces. Thus, symmetrical cold bending is performed sequentially according to different degrees of curvature. For ease of description, the curvature of the filament is defined according to the curvature of the mold grooves, and is marked as D0, D1, D2, ..., D6 from the outer to the inner ends, but this is not a limitation. By maintaining different degrees of curvature on the target filament, the external force applied to the target filament can be quantified and identified. X-ray diffraction is used for testing to obtain the shear stress of the target filament under different degrees of curvature. and radial stress .

[0040] Step S102: Determine the initial curvature, end curvature, and later curvature of the target filament based on each curvature and shear stress.

[0041] Specifically, in this embodiment of the invention, the change in the plastic deformation mechanism during the cold bending of the wire is determined by the trend of stress change, i.e., when different plastic deformation stages are entered and the corresponding curvature of each stage is used as the marker. During cold bending, as the external force increases, the wire first enters the elastic deformation stage, then the plastic deformation stage, until the stress begins to decrease when the internal dynamics of the wire shift from "work hardening-dominated" to "damage accumulation" or "softening mechanism-dominated". During this process, the shear stress, perpendicular to the plane being measured and tangent to the outer edge of the wire diameter circumference, is the most sensitive and changes the fastest. Furthermore, the rapid increase in shear stress in the initial stage of cold bending corresponds to the initiation stage of plastic deformation, where dislocations within the material begin to slip; when the shear stress enters a stable fluctuation state, it corresponds to the stable stage of plastic deformation, where large-scale dislocation slip and grain elongation and rearrangement occur; and when the shear stress shows a continuous decrease, it corresponds to the decline stage of plastic deformation, where dislocation pile-up and grain boundary cracking occur.

[0042] Therefore, this embodiment of the invention establishes the key curvature corresponding to the change in deformation mechanism during the cold bending plastic deformation process of wire based on shear stress, that is, the critical curvature node at which the plastic deformation mechanism undergoes a fundamental change, including: initial curvature, end curvature, and later curvature. Among them, the initial curvature (D... INI The first curvature benchmark after the shear stress meets the standard is the end curvature (D). FIN The critical curvature before the later stage of plastic deformation is denoted as D, and the later curvature is denoted as D. PDX () represents the curvature in the later stage of plastic deformation (after the shear stress decreases).

[0043] Step S103: Determine the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature.

[0044] Specifically, in this embodiment of the invention, after determining the change of the plastic deformation mechanism during the cold bending of the wire based on the change trend of shear stress and determining the key curvature, the degree of axial crack propagation of the target wire is determined by the change trend of shear stress before and after the key curvature.

[0045] This invention uses the critical curvature as a dual benchmark of time and deformation to compare and analyze the differences in the shear stress trends before and after the critical curvature, thereby determining the degree of axial crack propagation in the target filament. If, before the critical curvature, the shear stress maintains a stable increase or fluctuates smoothly without abnormal attenuation, it indicates that the internal structure of the filament is intact and no obvious cracks have appeared. If, after the critical curvature, the shear stress shows a slight decrease and the rate of decrease is slow, it is determined that the axial crack is in the initiation or slight propagation stage, at which point the stress concentration at the crack tip has not yet triggered large-scale crack propagation. If, after the critical curvature, the shear stress shows a rapid and significant attenuation trend, it is determined that the axial crack has entered a stable propagation or even unstable propagation stage, and the load-bearing capacity of the filament decreases significantly due to crack propagation. Therefore, this invention determines the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature.

[0046] Step S104: Determine the radial stress influence factor based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature.

[0047] Specifically, in this embodiment of the invention, during the cold bending of the wire, crack propagation not only includes axial cracks along the length direction but also radial cracks along the diameter direction, i.e., cracks extending perpendicular to the wire length and along the radius of the cross-section. The initiation and propagation of these cracks are directly regulated by the dynamic distribution and cumulative effect of radial stress, and their propagation degree cannot be fully characterized by changes in shear stress. Therefore, this embodiment of the invention, based on the determination of axial cracks by shear stress, further introduces the dynamic analysis dimension of radial stress. By accurately determining the radial crack propagation degree of the target wire through the trend of radial stress changes before and after the key bending degree, and by quantifying core characteristic parameters to construct a radial stress influence factor, a dual-dimensional crack assessment system of axial + radial stress is formed, achieving comprehensive coverage of the cold bending damage state of the wire.

[0048] Furthermore, during cold bending of the wire, its cross-section will generate a non-uniform radial stress field due to bending deformation: In the initial stage of cold bending, the surface of the wire bears radial tensile stress and the interior bears radial compressive stress, and the stress distribution is relatively uniform. At this time, the radial stress is mainly borne by the elastic deformation and plastic slip of the material, and there is no obvious stress concentration. As the curvature increases to the end curvature stage, the radial tensile stress continues to accumulate and gradually reaches its peak value. The stress distribution remains stable, and the material absorbs stress through grain rearrangement and dislocation slip, without the conditions for radial crack initiation. When the curvature exceeds the critical curvature and enters the later stage, the plastic deformation inside the material reaches saturation, and dislocations accumulate at grain boundaries or micro-defects, causing the radial tensile stress to be highly concentrated at the defect location. Once the concentrated stress exceeds the radial fracture strength of the material, it will trigger the initiation of radial cracks, and the cracks will continue to propagate along the radial tensile stress direction, which will lead to a reduction in the radial bearing area and a significant attenuation of the radial stress. Based on the inherent relationship between radial stress and radial cracks, this embodiment of the invention determines the radial stress influence factor according to the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature.

[0049] Step S105: Determine the cold bending crack resistance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. The cold bending crack resistance parameters are used to evaluate the cold bending crack resistance of the target wire.

[0050] Specifically, in this embodiment of the invention, in the evaluation system for the cold bending crack resistance of wire, the shear stress influence factor and the radial stress influence factor quantify the local crack resistance of the wire from two core dimensions: axial crack propagation inhibition and radial crack propagation inhibition, respectively. However, a single factor can only reflect some characteristics of cold bending damage: axial cracks easily lead to ductile failure in the length direction of the wire, while radial cracks easily cause penetrating brittle fracture of the cross section. During the cold bending process, the two often co-initiate and influence each other (e.g., radial crack propagation will aggravate shear stress concentration, thereby accelerating axial crack propagation). Therefore, a single factor cannot comprehensively characterize the overall crack resistance of the wire.

[0051] Based on this, the embodiments of the present invention use a dual-factor synergistic fusion logic to perform correlation analysis on the shear stress influence factor and the radial stress influence factor, construct multi-dimensional and quantifiable cold bending crack resistance parameters, realize a comprehensive and accurate evaluation of the cold bending crack resistance performance of the target wire, and provide core basis for wire process optimization, scenario selection and failure risk prediction, thereby breaking through the limitations of traditional single index evaluation and realizing the full-direction and full-stage quantitative characterization of cold bending cracks.

[0052] The present invention provides a method for evaluating the cold bending crack resistance performance of wire. By symmetrically cold bending the target wire at different curvatures, the radial stress and shear stress at preset test points are obtained at each curvature. Based on the shear stress, the initial curvature, end curvature, and later curvature are determined. The shear stress influence factor is determined based on the shear stress corresponding to the initial curvature, end curvature, and later curvature. Similarly, the radial stress influence factor is determined based on the radial stress corresponding to the initial curvature, end curvature, and later curvature. This allows for the determination of the cold bending crack resistance performance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. This method overcomes the limitation of existing standards that only determine the presence or absence of cracks, achieving a comprehensive quantitative evaluation of the crack initiation tendency, propagation direction, and propagation rate of the wire. It covers the core key indicators of cold bending crack resistance performance and improves the accuracy of wire quality evaluation.

[0053] This embodiment provides a method for evaluating the cold bending crack resistance of wire, which can be used in terminal devices such as computers. Figure 3 This is a flowchart of a method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention, such as... Figure 3 As shown, the process includes the following steps: Step S301: When the target wire is symmetrically cold-bent with the vertical line perpendicular to the tangential direction of the preset test point as the axis of symmetry, and with different degrees of curvature, the radial stress and shear stress at the preset test point under each degree of curvature are obtained. For details, please refer to... Figure 1 Step S101 of the illustrated embodiment will not be described again here.

[0054] Step S302: Determine the initial curvature, end curvature, and later curvature of the target filament based on each curvature and shear stress.

[0055] Specifically, step S302 includes: Step S3021: Sort the various curvatures from smallest to largest, and record the shear stress corresponding to each curvature after sorting.

[0056] Specifically, in this embodiment of the invention, during the testing process, the bending degree of the wire is defined according to the curvature of the mold groove, and marked as D0, D1, D2, ..., D6 from the outer side to the inner side of both ends, with the bending degree gradually increasing. Then, the target wire is tested sequentially according to the bending degree from smallest to largest, and the radial stress and shear stress under each bending degree are obtained. Regarding shear stress, in the early stage when the bending degree is small, the target wire is in the elastic deformation stage. As the bending degree increases, the shear stress gradually rises. However, when the plastic deformation stage is reached, the shear stress changes more slowly, and in the later stage of plastic deformation, the shear stress decreases as the bending degree increases. Therefore, when the bending degree changes from small to large, the overall trend of shear stress change is first from small to large, and then from large to small. Therefore, before determining the key bending degree, it is necessary to sort the bending degrees from smallest to largest, and use the sorted bending degrees as a benchmark to record the shear stress corresponding to each bending degree sequentially, to ensure that the trend of shear stress change conforms to the theoretical basis.

[0057] Step S3022: Based on each shear stress, find the first shear stress that first exceeds the preset threshold, and take the curvature corresponding to the first shear stress as the initial curvature.

[0058] Specifically, in this embodiment of the invention, the curvature with significant shear stress is used as the initial curvature. For example, 100 is used as a preset threshold, but this is not a limitation, because the shear stress gradually increases in the early stage of deformation. Therefore, the shear stress that first exceeds the preset threshold is found and used as the first shear stress, and the curvature corresponding to the first shear stress is used as the initial curvature D. INI .

[0059] Step S3023: Based on each shear stress, find the largest second shear stress and take the curvature corresponding to the second shear stress as the end curvature.

[0060] Specifically, in this embodiment of the invention, the curvature where the degree of curvature is close to the late stage of plastic deformation but the shear stress has not decreased is taken as the end curvature. In this embodiment of the invention, the decrease in shear stress value is regarded as the test area entering the late stage of plastic deformation. Therefore, in the trend of shear stress increasing and then decreasing again, the maximum shear stress is found and used as the second shear stress, and the corresponding curvature is taken as the end curvature.

[0061] Step S3024: Based on each shear stress, find the third shear stress that first decreases after the second shear stress, and take the curvature corresponding to the third shear stress as the later curvature.

[0062] Specifically, in this embodiment of the invention, the bending degree is at a certain point in the later stage of plastic deformation, i.e., when the shear stress has decreased. Therefore, starting from the maximum shear stress (the second shear stress), the search proceeds backward to determine the first decrease in the third shear stress after the maximum shear stress.

[0063] Step S303: Determine the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature.

[0064] Specifically, step S303 includes: Step S3031: The absolute value of the first shear stress corresponding to the initial curvature is taken as the first shear stress influence factor, the absolute value of the second shear stress corresponding to the end curvature is taken as the second shear stress influence factor, and the absolute value of the third shear stress corresponding to the later curvature is taken as the third shear stress influence factor.

[0065] Specifically, in this embodiment of the invention, a first shear stress influence factor is defined. , The initial curvature D INI Corresponding shear stress; second shear stress influence factor , End curvature D FIN Corresponding shear stress; third shear stress influence factor , For later bending degree D PDX The corresponding shear stress.

[0066] Step S3032: Calculate the first difference between the absolute value of the second shear stress and the absolute value of the first shear stress, and use the ratio between the first difference and the absolute value of the second shear stress as the fourth shear stress influence factor.

[0067] Specifically, in this embodiment of the invention, a fourth shear stress influence factor is defined. , D INI To D FIN The rate of change of shear stress, i.e. .

[0068] Step S3033: Calculate the second difference between the absolute value of the second shear stress and the absolute value of the third shear stress, and use the ratio between the second difference and the absolute value of the second shear stress as the fifth shear stress influence factor.

[0069] Specifically, in this embodiment of the invention, a fifth shear stress influence factor is defined. , D PDX To D FIN The rate of change of shear stress, i.e. This invention constructs a two-dimensional shear stress influence factor system based on the absolute value of the basic shear stress and the rate of stress change. This system can reflect the stress state of the wire at different stages of plastic deformation and quantify the stress change trend, comprehensively characterizing the toughness of crack initiation and early propagation, and providing a direct basis for the quantitative classification of wire toughness.

[0070] Furthermore, since shear stress is the primary driving force for plastic deformation, it typically leads to ductile fracture. It can be considered that... The larger, The smaller the value, the slower the transformation process of the wire's internal plastic deformation mechanism, such as the transition from work hardening to softening. The better the toughness, the smaller the crack propagation rate perpendicular to the axis (radial), and the more it propagates along the axial direction.

[0071] Step S304: Determine the radial stress influence factor based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature.

[0072] Specifically, step S304 includes: Step S3041: The absolute value of the first radial stress corresponding to the initial curvature is taken as the first radial stress influence factor, the absolute value of the second radial stress corresponding to the end curvature is taken as the second radial stress influence factor, and the absolute value of the third radial stress corresponding to the later curvature is taken as the third radial stress influence factor.

[0073] Specifically, in this embodiment of the invention, a first radial stress influence factor is defined. , The initial curvature D INI Corresponding radial stress; second radial stress influence factor , End curvature D FIN Corresponding radial stress; third radial stress influence factor , For later bending degree D PDX The corresponding radial stress.

[0074] Step S3042: The absolute value of the sum of the second radial stress and the third radial stress is used as the fourth radial stress influence factor.

[0075] Specifically, in this embodiment of the invention, a fourth radial stress influence factor is defined. This invention reflects the overall change in radial stress value during the process from end-bending curvature to later-bending curvature, i.e., the reduction of shear stress. It constructs two evaluation indicators for cold bending crack resistance, which can quantify the axial crack propagation tendency and radial crack propagation rate respectively, achieving differentiated evaluation of crack resistance performance and overcoming the current limitation of qualitatively assessing cold bending performance solely by judging the presence or absence of cracks. Simultaneously, it considers the synergistic evaluation of toughness and crack resistance performance; toughness can be determined through the shear stress influence factor, and the radial stress influence factor can assist in judging the degree and direction of crack propagation during cold bending, achieving comprehensive performance characterization.

[0076] Furthermore, when crack propagation preferentially occurs axially, it offsets the radial tensile stress (tensile stress on the outer side of the wire circumference), resulting in a faster decrease in radial stress and a quicker transition from tensile to compressive stress. At this point, some cracks may also propagate radially, causing a decrease in radial stress, but at a relatively slower rate. Therefore, The larger the value, the more the radial stress increases overall, and the more the crack propagates radially.

[0077] Step S305: Determine the cold bending crack resistance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. The cold bending crack resistance parameters are used to evaluate the cold bending crack resistance of the target wire.

[0078] Specifically, step S305 includes: Step S3051: The ratio of the second shear stress influence factor to the fourth radial stress influence factor is used as the first cold bending crack resistance performance evaluation index. The first cold bending crack resistance performance evaluation index characterizes the axial cold bending crack resistance performance of the target wire.

[0079] Specifically, in this embodiment of the invention, the first cold bending crack resistance performance evaluation index is used. Characterizing the axial cold bending crack resistance of the target wire, a first cold bending crack resistance performance evaluation index is defined. . The larger the value, the more the cracks in the wire tend to propagate axially during the later stages of cold bending, and the greater the crack propagation in that direction.

[0080] Step S3052: The ratio of the fifth shear stress influence factor and the second radial stress influence factor is used as the second cold bending crack resistance performance evaluation index. The second cold bending crack resistance performance evaluation index characterizes the radial cold bending crack resistance performance of the target wire.

[0081] Specifically, in this embodiment of the invention, the second cold bending crack resistance performance evaluation index is used. Characterizing the radial cold bending crack resistance of the target wire, a second cold bending crack resistance performance evaluation index is defined. . A larger value indicates a higher rate of radial crack propagation during the later stages of cold bending. If, during cold bending, the crack propagation of the wire tends to be more axial and less radial, it indicates better plasticity, a tendency towards ductile fracture, and superior crack resistance.

[0082] Step S306: Compare the first cold bending crack resistance performance evaluation index of the first wire and the second wire, and compare the second cold bending crack resistance performance evaluation index of the first wire and the second wire to obtain the evaluation result.

[0083] Specifically, in this embodiment of the invention, in actual operation, wires of the same specification but different materials are randomly selected within a range where the wire diameter is greater than or equal to a first threshold and less than or equal to a second threshold. These different wires are then tested separately to determine the corresponding cold bending crack resistance parameters. Based on these parameters, the cold bending crack resistance performance of the wires is compared and evaluated, thus providing a basis for practical applications. The first threshold is set to 0.038 ± 0.003 mm, and the second threshold is set to 2 ± 0.03 mm; these are merely examples and not intended to be limiting.

[0084] For example, two tungsten wires, A1 and A2, with a diameter of 0.08 mm and different added elements, were fabricated. A1 was treated with Re, and A2 with La. It is generally believed that the addition of Re is more beneficial to improving the toughness of tungsten wires. A1 and A2 were tested according to the testing method of this embodiment of the invention to obtain their radial stress and shear stress. Based on the radial stress and shear stress, the shear stress influence factor and radial stress influence factor of A1 and A2 were determined, and the cold bending crack resistance parameters of A1 and A2 were determined respectively. The results are shown in the table below: Table 1 Radial stress and shear stress of A1 and A2

[0085] Table 2 Evaluation parameters for cold bending crack resistance of A1 and A2

[0086] It can be seen that A1's Larger A smaller value indicates that A1 has better toughness, which is consistent with theory; in this case, cracks in A1 should be more inclined to propagate axially. A2's... The larger value indicates that the crack propagation is more radial. Based on the cold bending crack resistance evaluation indicators, A1... Larger The smaller value indicates that the crack propagation of the wire is more inclined to the axial direction during cold bending, and the crack propagation degree in this direction is greater. The crack propagation rate in the radial direction is smaller, and the cold bending crack resistance is better.

[0087] For example, two tungsten wires, A3 and A4, with the same manufacturing process and a diameter of 0.18 mm, are produced. Due to other factors in the manufacturing process, micro-cracks appear on the surface of A3, such as... Figure 4 As shown in the figure. A3 and A4 were tested according to the test method of this embodiment of the invention to obtain the radial stress and shear stress of A3 and A4. Based on the radial stress and shear stress, the shear stress influence factor and radial stress influence factor of A3 and A4 were determined respectively, and the cold bending crack resistance parameters of A3 and A4 were determined respectively. The results are shown in the table below: Radial stress and shear stress in Tables 3A3 and A4

[0088] Table 4. Evaluation parameters for cold bending crack resistance of A3 and A4

[0089] Theoretically, the presence of surface cracks will inevitably reduce the cold bending crack resistance of the wire. Actual test results show that A4... Larger The similarity indicates that crack propagation during A4 cold bending tends to be more axial, with a greater degree of crack propagation in this direction, while the crack propagation rate in the radial direction is similar; the fracture mode tends to be ductile fracture, and the cold bending crack resistance is better, which is consistent with the theory, further proving the reliability of the wire cold bending crack resistance evaluation method provided in the embodiments of the present invention.

[0090] The present invention provides a method for evaluating the cold bending crack resistance performance of wire. By symmetrically cold bending the target wire at different curvatures, the radial stress and shear stress at preset test points are obtained at each curvature. Based on the shear stress, the initial curvature, end curvature, and later curvature are determined. The shear stress influence factor is determined based on the shear stress corresponding to the initial curvature, end curvature, and later curvature. Similarly, the radial stress influence factor is determined based on the radial stress corresponding to the initial curvature, end curvature, and later curvature. This allows for the determination of the cold bending crack resistance performance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. This method overcomes the limitation of existing standards that only determine the presence or absence of cracks, achieving a comprehensive quantitative evaluation of the crack initiation tendency, propagation direction, and propagation rate of the wire. It covers the core key indicators of cold bending crack resistance performance and improves the accuracy of wire quality evaluation.

[0091] This embodiment provides a method for evaluating the cold bending crack resistance of wire, which can be used in terminal devices such as computers. Figure 5 This is a flowchart of a method for evaluating the cold bending crack resistance of wire according to an embodiment of the present invention, such as... Figure 5 As shown, the process includes the following steps: Step S501: When the target wire is symmetrically cold-bent with the vertical line of the tangential direction of the preset test point as the axis of symmetry, and is successively subjected to different degrees of curvature, the radial stress and shear stress of the preset test point under each degree of curvature are obtained.

[0092] Specifically, step S501 includes: Step S5011: Adjust the height of the mold to the original height so that the laser positioning spot of the X-ray diffractometer is within the diameter range of the target filament. Determine the height fluctuation value according to the radius of the target filament. Using the original height as a reference, determine the first upward floating height and the second downward floating height according to the height fluctuation value.

[0093] Specifically, in embodiments of the present invention, it can be carried out according to as follows Figure 2 The grooved mold shown depicts the deployment of the target filament, exposing a pre-set test point at the top of the mold. X-ray diffraction is used to obtain the stress at test point C2 of the drawn filament under different curvatures. Alternatively, it can be done as follows... Figure 6 As shown, the target filament is placed on the conductive adhesive on the sample stage, pressed slightly, and then fixed. Figure 6 C2 was used as a preset test point, and the stress at the C2 test point of the drawn wire under different curvatures was obtained by X-ray diffraction.

[0094] The preset test point is the highest point on the surface of the wire. When the wire cracks under cold bending stress, such as... Figure 7 As shown, cracks preferentially appear on the stressed side, and a propagation process is required for them to extend to the area of ​​the preset test point. For example... Figure 8 As shown in (a), the experiment proved that when the curvature is small, the crack is only on the side, and no crack was observed in the test area. Only graphite emulsion that had fallen off due to the crack was observed on the side. Figure 8 As shown in (b), with increased curvature, cracks appear in the test area. When the crack has not propagated to the test area, the measured stress will still maintain its original trend, such as changes in force direction or value. Therefore, this delay effect can be used to further differentiate and quantify the degree of crack propagation. This delay effect can be increased or decreased by controlling the X-ray irradiation volume. The X-ray irradiation volume includes the irradiation area and the transmission depth. The size of the irradiation area can be controlled by the collimator diameter; in the experiment, a diameter of 0.5 mm was used (commercially available collimators typically have diameters of 0.05 mm to 2 mm). The transmission depth can be controlled by adjusting the diffraction intensity and the sample height.

[0095] The embodiments of this invention mainly employ the "three-height method," which controls the transmission depth by controlling the sample height. Three height values ​​are used for testing at the same point. This reduces the influence of the curved surface of the wire, amplifies differences, and allows for better observation of the trend in test results. Furthermore, it serves as a repeatable test, enhancing the accuracy of trend judgment. Therefore, by minimizing the X-ray irradiation volume, the delay effect can be increased, and the differences amplified.

[0096] In some alternative implementations, it can be deployed in, for example... Figure 2 The groove mold shown is used as an example for testing. The preset test point is located at the highest point of the wire axis. When testing the preset predicted point, the light reflection should be the strongest and the light spot brightness should be the highest. However, in actual testing, when the wire diameter is small, the intensity of light reflection is not obvious, and the curved surface of the wire also has contrast, making it often impossible to determine the true height during testing.

[0097] Therefore, in this embodiment of the invention, the height of the mold is adjusted so that the laser positioning spot of the X-ray diffractometer is within the diameter range of the wire material, and this height is used as the original height, with the radius of the target wire material as a reference to set the height fluctuation value (e.g., ...). Φ The tungsten wire with a specification of 0.18mm has a float value of 0.1mm. The first height for upward float and the second height for downward float are determined respectively. The second height, the original height and the first height are marked as H0.9, H1.0 and H1.1 respectively, so that the same position can be tested with three height values.

[0098] Step S5012: For any curvature, control the X-ray diffractometer to measure the preset test points according to the original height, the first height and the second height respectively, and obtain multiple radial stress measurement values ​​and multiple shear stress measurement values.

[0099] Specifically, in this embodiment of the invention, for each degree of curvature, the preset test point is measured three times according to the above-mentioned "three-height method", so that three radial stress measurement values ​​can be obtained simultaneously. , , and three shear stress measurements , , As shown in Table 1 above, but not limited to this.

[0100] For example, a 5-10cm section of wire is cut and fixed on the sample stage while maintaining a certain degree of curvature. The relationship between the sample coordinate system and the laboratory coordinate system is as follows: when the horizontal rotation angle φ of the instrument's sample stage is 0°, the axis of the wire section to be tested is parallel to the diffraction path. The test conditions of the measuring instrument are determined as follows: using W as an example, a Cu target, a scanning angle of 40°-42°, a step size of 0.03°, and a dwell time of 0.5s per step. Using sin²... ψ The way the law tilts, φ Angles can be 0° and 180°. ψ The angle range is 0° to 50°, with 5 to 10 points taken at equal intervals. The collimation tube diameter is 0.05mm-0.5mm. The measuring instrument is a Bruker D8 DISCOVER X-ray diffractometer. Three tests were conducted on the preset test points of the filament at the three heights mentioned above. This is only an example and is not a limitation.

[0101] Step S5013: Average the multiple radial stress measurements to obtain the radial stress, and average the multiple shear stress measurements to obtain the shear stress.

[0102] Specifically, in this embodiment of the invention, the above three radial stress measurements are... , , The average is calculated to obtain the radial stress of the target wire at the current curvature. Meanwhile, the above three shear stress measurements... , , The average stress is calculated to obtain the shear stress of the target wire at the current curvature. .

[0103] Step S502: Determine the initial curvature, end curvature, and final curvature of the target filament based on various curvatures and shear stresses. See details below. Figure 3 Step S301 of the illustrated embodiment will not be described again here.

[0104] Step S503: Determine the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature. For details, please refer to [link to relevant documentation]. Figure 3 Step S303 of the illustrated embodiment will not be described again here.

[0105] Step S504: Determine the radial stress influence factor based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature. For details, please refer to [link to relevant documentation]. Figure 3 Step S304 of the illustrated embodiment will not be described again here.

[0106] Step S505: Determine the cold bending crack resistance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. These parameters are used to evaluate the cold bending crack resistance of the target wire. For details, please refer to [link to relevant documentation]. Figure 3 Step S305 of the illustrated embodiment will not be described again here.

[0107] This embodiment also provides a device for evaluating the cold bending crack resistance of wire. This device is used to implement the above embodiments and preferred embodiments, and will not be repeated for details already described. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0108] This embodiment provides a device for evaluating the cold bending crack resistance of wire, such as... Figure 9 As shown, it includes: The stress measurement module 901 is used to obtain the radial stress and shear stress at the preset test points under different curvatures when the target wire is symmetrically cold-bent with the vertical line of the tangential direction of the preset test point as the axis of symmetry.

[0109] The bending degree determination module 902 is used to determine the initial bending degree, end bending degree and later bending degree of the target filament based on various bending degrees and shear stresses.

[0110] The first factor determination module 903 is used to determine the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature.

[0111] The second factor determination module 904 is used to determine the radial stress influence factor based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature.

[0112] The crack resistance evaluation module 905 is used to determine the cold bending crack resistance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. The cold bending crack resistance parameters are used to evaluate the cold bending crack resistance of the target wire.

[0113] In some alternative implementations, the stress measurement module 901 includes: The height determination unit is used to adjust the height of the mold to the original height so that the laser positioning spot of the X-ray diffractometer is within the diameter range of the target filament. It determines the height fluctuation value based on the radius of the target filament, and determines the first upward floating height and the second downward floating height based on the original height.

[0114] The stress measurement unit is used to control the X-ray diffractometer to measure preset test points at the original height, the first height, and the second height for any curvature, thereby obtaining multiple radial stress measurement values ​​and multiple shear stress measurement values.

[0115] The stress determination unit is used to average multiple radial stress measurements to obtain radial stress, and to average multiple shear stress measurements to obtain shear stress.

[0116] In some alternative implementations, the bending degree determination module 902 includes: The overall shear stress sorting unit is used to sort the various curvatures from smallest to largest and record the shear stress corresponding to each curvature after sorting.

[0117] The initial curvature determination unit is used to find the first shear stress that first exceeds a preset threshold based on each shear stress, and to take the curvature corresponding to the first shear stress as the initial curvature.

[0118] The end curvature determination unit is used to find the maximum second shear stress based on each shear stress, and to take the curvature corresponding to the second shear stress as the end curvature.

[0119] The post-bending degree determination unit is used to find the third shear stress that first decreases after the second shear stress based on each shear stress, and to take the bending degree corresponding to the third shear stress as the post-bending degree.

[0120] In one optional implementation, the first factor determination module 903 includes: The first determining unit is used to take the absolute value of the first shear stress corresponding to the initial curvature as the first shear stress influence factor, the absolute value of the second shear stress corresponding to the end curvature as the second shear stress influence factor, and the absolute value of the third shear stress corresponding to the later curvature as the third shear stress influence factor.

[0121] The second determining unit is used to calculate the first difference between the absolute value of the second shear stress and the absolute value of the first shear stress, and to use the ratio between the first difference and the absolute value of the second shear stress as the fourth shear stress influence factor.

[0122] The third determining unit is used to calculate the second difference between the absolute value of the second shear stress and the absolute value of the third shear stress, and the ratio between the second difference and the absolute value of the second shear stress is used as the fifth shear stress influence factor.

[0123] In some optional implementations, the second factor determination module 904 includes: The fourth determining unit is used to take the absolute value of the first radial stress corresponding to the initial curvature as the first radial stress influence factor, the absolute value of the second radial stress corresponding to the end curvature as the second radial stress influence factor, and the absolute value of the third radial stress corresponding to the later curvature as the third radial stress influence factor.

[0124] The fifth determining unit is used to take the absolute value of the sum of the second radial stress and the third radial stress as the fourth radial stress influence factor.

[0125] In some alternative implementations, the crack resistance evaluation module 905 includes: The first evaluation index determination unit is used to take the ratio of the second shear stress influence factor to the fourth radial stress influence factor as the first cold bending crack resistance performance evaluation index. The first cold bending crack resistance performance evaluation index characterizes the axial cold bending crack resistance performance of the target wire.

[0126] The second evaluation index determination unit is used to take the ratio of the fifth shear stress influence factor and the second radial stress influence factor as the second cold bending crack resistance performance evaluation index. The second cold bending crack resistance performance evaluation index characterizes the radial cold bending crack resistance performance of the target wire.

[0127] In some alternative embodiments, the apparatus further includes: The performance comparison module is used to compare the first cold bending crack resistance performance evaluation index of the first wire and the second wire, and to compare the second cold bending crack resistance performance evaluation index of the first wire and the second wire to obtain the evaluation results. In the evaluation results, the larger the first cold bending crack resistance performance evaluation index and the smaller the second cold bending crack resistance performance evaluation index, the better the cold bending crack resistance performance of the corresponding wire.

[0128] The wire cold bending crack resistance evaluation device provided in this embodiment of the invention can execute the wire cold bending crack resistance evaluation method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the above modules and units are the same as in the corresponding embodiments described above, and will not be repeated here.

[0129] Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0130] The following is a detailed reference. Figure 10 This diagram illustrates a suitable structural schematic for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 1001, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from memory 1008 into random access memory (RAM) 1003. The RAM 1003 also stores various programs and data required for the operation of the electronic device. The processor 1001, ROM 1002, and RAM 1003 are interconnected via a bus 1004. An input / output (I / O) interface 1005 is also connected to the bus 1004.

[0131] Typically, the following devices can be connected to the I / O interface 1005: input devices 1006 including, for example, a touchscreen, touchpad, keyboard, mouse, camera, microphone, accelerometer, gyroscope, etc.; output devices 1007 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; memory devices 1008 including, for example, magnetic tape, hard disk, etc.; and communication devices 1009. Communication device 1009 allows electronic devices to exchange data via wireless or wired communication with other devices. Although Figure 10 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0132] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 1009, or installed from a memory 1008, or installed from a ROM 1002. When the computer program is executed by the processor 1001, it performs the functions defined in the wire cold bending crack resistance evaluation method of the embodiments of the present invention.

[0133] Figure 10 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0134] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the method for evaluating the cold bending crack resistance of wire shown in the above embodiments is implemented.

[0135] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0136] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for evaluating the cold bending crack resistance of wire, characterized in that, The method includes: When the target wire is symmetrically cold-bent with the vertical line of the tangential direction of the preset test point as the axis of symmetry, and is successively subjected to different degrees of curvature, the radial stress and shear stress of the preset test point under each degree of curvature are obtained. The initial curvature, end curvature, and later curvature of the target filament are determined based on the respective curvatures and shear stresses. The shear stress influence factor is determined based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature. The radial stress influence factor is determined based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature. The cold bending crack resistance parameters of the target wire are determined based on the shear stress influence factor and the radial stress influence factor. These parameters are used to evaluate the cold bending crack resistance of the target wire.

2. The method according to claim 1, characterized in that, The determination of the initial curvature, end curvature, and later curvature of the target filament based on each of the curvatures and the shear stress includes: The curvatures are sorted from smallest to largest, and the shear stress corresponding to each curvature is recorded sequentially. Based on each of the shear stresses, find the first shear stress that first exceeds a preset threshold, and take the curvature corresponding to the first shear stress as the initial curvature; Based on each of the shear stresses, the largest second shear stress is found, and the curvature corresponding to the second shear stress is taken as the end curvature; Based on each of the shear stresses, find the third shear stress that first decreases after the second shear stress, and use the curvature corresponding to the third shear stress as the later curvature.

3. The method according to any one of claims 1 or 2, characterized in that, The step of determining the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature includes: The absolute value of the first shear stress corresponding to the initial curvature is taken as the first shear stress influence factor, the absolute value of the second shear stress corresponding to the end curvature is taken as the second shear stress influence factor, and the absolute value of the third shear stress corresponding to the later curvature is taken as the third shear stress influence factor. Calculate the first difference between the absolute value of the second shear stress and the absolute value of the first shear stress, and use the ratio between the first difference and the absolute value of the second shear stress as the fourth shear stress influence factor; Calculate the second difference between the absolute value of the second shear stress and the absolute value of the third shear stress, and use the ratio between the second difference and the absolute value of the second shear stress as the fifth shear stress influence factor.

4. The method according to claim 3, characterized in that, The step of determining the radial stress influence factor based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature includes: The absolute value of the first radial stress corresponding to the initial curvature is taken as the first radial stress influence factor, the absolute value of the second radial stress corresponding to the end curvature is taken as the second radial stress influence factor, and the absolute value of the third radial stress corresponding to the later curvature is taken as the third radial stress influence factor. The absolute value of the sum of the second radial stress and the third radial stress is used as the fourth radial stress influence factor.

5. The method according to claim 4, characterized in that, The determination of the cold bending crack resistance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor includes: The ratio of the second shear stress influence factor to the fourth radial stress influence factor is used as the first cold bending crack resistance performance evaluation index, which characterizes the axial cold bending crack resistance performance of the target wire. The ratio of the fifth shear stress influence factor to the second radial stress influence factor is used as the second cold bending crack resistance performance evaluation index, which characterizes the radial cold bending crack resistance performance of the target wire.

6. The method according to claim 5, characterized in that, After selecting a first wire and a second wire within a range where the wire diameter is greater than or equal to a first threshold and less than or equal to a second threshold, and determining the corresponding cold bending crack resistance parameters, the method further includes: The evaluation results are obtained by comparing the first cold bending crack resistance performance evaluation index of the first wire and the second wire, and comparing the second cold bending crack resistance performance evaluation index of the first wire and the second wire. In the evaluation results, the first cold bending crack resistance performance evaluation index is larger and the second cold bending crack resistance performance evaluation index is smaller, and the corresponding wire has better cold bending crack resistance performance.

7. The method according to claim 1, characterized in that, The target filament is fixed to the mold according to different curvatures. During the symmetrical cold bending process according to different curvatures, the radial stress and shear stress at the preset test points under each curvature are obtained, including: Adjust the height of the mold to the original height so that the laser positioning spot of the X-ray diffractometer is within the diameter range of the target filament, and determine the height fluctuation value according to the radius of the target filament. Using the original height as a reference, determine the first upward floating height and the second downward floating height according to the height fluctuation value. For any of the aforementioned curvatures, the X-ray diffractometer is controlled to measure the preset test points according to the original height, the first height, and the second height, respectively, to obtain multiple radial stress measurement values ​​and multiple shear stress measurement values; The radial stress is obtained by averaging the multiple radial stress measurements, and the shear stress is obtained by averaging the multiple shear stress measurements.

8. A device for evaluating the cold bending crack resistance of wire, characterized in that, The device includes: The stress measurement module is used to obtain the radial stress and shear stress at the preset test point under each degree of curvature when the target wire is symmetrically cold-bent with the vertical line of the tangential direction of the preset test point as the axis of symmetry. A bending degree determination module is used to determine the initial bending degree, end bending degree, and later bending degree of the target filament based on each of the bending degrees and the shear stress; The first factor determination module is used to determine the shear stress influence factor based on the first shear stress corresponding to the initial curvature, the second shear stress corresponding to the end curvature, and the third shear stress corresponding to the later curvature. The second factor determination module is used to determine the radial stress influence factor based on the first radial stress corresponding to the initial curvature, the second radial stress corresponding to the end curvature, and the third radial stress corresponding to the later curvature. The crack resistance evaluation module is used to determine the cold bending crack resistance parameters of the target wire based on the shear stress influence factor and the radial stress influence factor. The cold bending crack resistance parameters are used to evaluate the cold bending crack resistance of the target wire.

9. An electronic device, characterized in that, include: The device includes a memory and a processor, which are interconnected and the memory stores computer instructions. The processor executes the computer instructions to perform the method for evaluating the cold bending crack resistance of wire as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the evaluation of the cold bending crack resistance of the wire as described in any one of claims 1 to 7.

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