Method for testing limit hole flanging height of high-strength steel and related equipment

Abstract

The invention provides a method and related equipment for testing the limit hole flanging height of high-strength steel, and relates to the technical field of metallurgical production, and the method comprises the following steps: manufacturing a round hole with a preset hole diameter in the center of a to-be-tested plate; performing a hole flanging test based on the hole flanging diameter to obtain a hole flanging edge state; and based on the hole flanging edge state, changing the preset hole diameter until the preset hole diameter is small and the hole flanging edge state is crack-free, and determining the hole flanging height corresponding to the hole flanging product as the limit hole flanging height corresponding to the current hole flanging diameter.

Description

Technical Field

[0001] The present application relates to the field of metallurgical production technology, and in particular to a method for testing the ultimate hole-turning height of high-strength steel and related equipment. Background Art

[0002] In the production and application of high-strength steel, hole-flanging technology is a key process. Flanging refers to flanging the plate blank with pre-processed holes, so that the edge of the hole stands up to form a flange perpendicular to the plate surface. This process is widely used in the automotive, machinery and other industries. In particular, high-strength steel is prone to cracks and fractures during the hole-flanging process due to its high material strength and low plasticity, which greatly affects the quality of the finished product.

[0003] With the development and application of high-strength steel, the hole-expanding height limit of the material has become an important indicator for evaluating its formability. However, the existing technology is difficult to comprehensively and accurately evaluate the formability of high-strength steel under different hole-expanding conditions, resulting in a mismatch between the hole-expanding capacity of the material and the hole-expanding process requirements, affecting product quality and production efficiency. Therefore, a test method that can effectively evaluate the hole-expanding height limit of high-strength steel is urgently needed to guide the actual production process and ensure that the material forming is consistent with the process requirements. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] In a first aspect, the present application provides a method for testing the limit hole height of high-strength steel, comprising:

[0006] Make a circular hole of preset diameter in the center of the sheet to be tested;

[0007] Perform a hole turning test based on the hole turning diameter to obtain the edge status of the hole turning;

[0008] Based on the above-mentioned punching edge state, the above-mentioned preset hole diameter is changed until the above-mentioned preset hole diameter is smaller and the above-mentioned punching edge state is crack-free, and the punching height corresponding to the punching product is determined as the limit punching height corresponding to the current punching diameter.

[0009] In a feasible implementation manner, the above-mentioned changing of the preset aperture based on the above-mentioned hole edge state includes:

[0010] When the edge of the hole is crack-free, the preset diameter of the circular hole is reduced;

[0011] When the edge of the punched hole is cracked, the preset hole diameter of the circular hole is increased.

[0012] In a feasible implementation, it also includes:

[0013] Changing the above-mentioned hole turning diameter to obtain the corresponding limit hole turning height under different above-mentioned hole turning diameters;

[0014] Curve fitting is performed based on all the tested hole turning diameters and their corresponding limit hole turning heights to obtain the limit hole turning height curve.

[0015] In a feasible implementation manner, the above-mentioned hole-bursting diameter is achieved by changing the outer diameter of the hole-bursting punch, the inner diameter of the hole-bursting die, and the inner diameter of the punch and die positioning rings.

[0016] In a feasible implementation, it also includes:

[0017] The final preset hole diameter corresponding to the punching product with the maximum punching height under the first punching diameter is determined as the starting experimental hole diameter of the current punching diameter, wherein the above-mentioned first punching diameter is the punching diameter with the smaller difference with the above-mentioned current punching diameter among the punching diameters that have been tested.

[0018] In one possible implementation,

[0019] The difference between the iterative experimental aperture and the above-mentioned initial experimental aperture is a preset integer multiple of the iterative increase step size;

[0020] In the case where the current hole punching diameter is greater than the first hole punching diameter, the preset integer multiple is a positive integer;

[0021] In the case where the current punching diameter is smaller than the first punching diameter, the preset integer multiple is a negative integer.

[0022] In one possible implementation,

[0023] When the above-mentioned hole turning diameter is within the first interval, the growth rate of the above-mentioned limit hole turning height changes linearly;

[0024] When the drilling diameter is within the second interval, the growth rate of the limit drilling height changes nonlinearly.

[0025] In the second aspect, the present application proposes a testing device for the limit punching height of high-strength steel, comprising:

[0026] Aperture setting unit, used to make a circular hole of preset aperture in the center of the sheet to be tested;

[0027] A state acquisition unit, used for performing a hole turning test based on the hole turning diameter to obtain the hole turning edge state;

[0028] The height determination unit is used to change the preset hole diameter based on the above-mentioned hole edge state until the preset hole diameter is smaller and the above-mentioned hole edge state is crack-free, and the hole height corresponding to the hole-punching product is determined as the limit hole height corresponding to the current hole-punching diameter.

[0029] In a third aspect, an electronic device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor is used to implement the steps of a method for testing the limit hole-turning height of high-strength steel as described in any one of the first aspects above when executing the computer program stored in the memory.

[0030] In a fourth aspect, the present application further proposes a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, a method for testing the limit hole-turning height of high-strength steel as described in any one of the first aspects above is implemented.

[0031] In summary, the embodiment of the present invention provides a method for testing the limit hole height of high-strength steel. By adopting multiple hole-turning experiments and gradually adjusting the aperture and hole-turning height, the limit hole-turning height under different hole-turning diameters can be accurately grasped. During the experiment, the aperture is gradually reduced or increased until the current hole-turning height is obtained when there is no crack on the edge of the hole-turning. This precise control method based on the crack formation situation minimizes the error in the evaluation process and greatly improves the reliability of the evaluation results. At the same time, the method can significantly reduce the material cracking during the hole-turning process, improve the overall quality of the material in the hole-turning forming, and ensure the safety and stability of the product. The present invention is applicable to a variety of hole-turning processing technologies, including punching, wire cutting, laser cutting, etc., and has strong process adaptability. In addition, different types of high-strength steel and other high-strength materials can be tested for the limit hole-turning height by this method. The traditional hole-turning process parameter adjustment usually relies on experience judgment, and the operation is complicated and time-consuming. The design of the hole-turning mold of the present invention ensures high repeatability and ease of operation in the hole-turning process, and the accurate hole-turning height can be obtained by adjusting the aperture according to the experimental results. Through this simplified process, the complexity and time consumption of the process are greatly reduced, and the overall production efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present specification. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0033] Figure 1 A flow chart of a method for testing the maximum hole-turning height of high-strength steel provided in an embodiment of the present application;

[0034] Figure 2 A schematic diagram of the hole punching die structure provided in an embodiment of the present application;

[0035] Figure 3 A graph showing the limit hole turning height provided in the embodiment of the present application;

[0036] Figure 4 A schematic diagram of the structure of a testing device for the limit hole-turning height of high-strength steel provided in an embodiment of the present application;

[0037] Figure 5 Schematic diagram of the structure of the electronic equipment for testing the extreme hole-turning height of high-strength steel provided in the embodiment of the present application. DETAILED DESCRIPTION

[0038] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0039] See also Figure 1 , which is a flow chart of a method for testing the limit hole-turning height of high-strength steel provided in an embodiment of the present application, which may specifically include:

[0040] S110, making a circular hole of a preset aperture at the center of the sheet to be tested;

[0041] For example, making a circular hole with a preset aperture in the center of the sheet to be tested is a key initial step in the entire punching experiment. It is crucial to ensure the accuracy of the hole and the position. The purpose of this step is to provide basic conditions for subsequent punching tests, control the deformation path of the material during the punching process through the preset aperture, ensure that the sheet can be uniformly formed in subsequent operations, and accurately evaluate the punching height limit.

[0042] The high-strength steel sheet to be tested is fixed in the positioning fixture to ensure that it does not move or deviate. In order to ensure that the circular hole is coaxial with the center of the punching die, high-precision hole-making equipment, such as CNC punching machine, laser cutting machine or wire cutting equipment, is used to make the hole. When selecting equipment, the thickness of the sheet, the hardness of the material and the diameter of the hole must be considered to ensure that the dimensional accuracy of the hole can meet the process requirements.

[0043] High-strength steel sheets have extremely high strength and low ductility, so stress concentration is easy to occur during the hole making process, resulting in cracks or microcracks on the surface of the material. These cracks may expand during the subsequent hole punching process, affecting the integrity of the hole edge. Therefore, when processing the hole diameter, a low-speed and high-precision hole making process must be used to avoid any processing defects. In addition, the size of the hole diameter needs to be preset according to the experimental requirements. Usually, an aperture close to the limit of the material's hole punching capacity is selected so that the aperture can be gradually reduced or enlarged, thereby obtaining the maximum height of the hole punching under different conditions.

[0044] The center hole of the sheet must be coaxial with the punching die to ensure uniform forming of the material during the punching process. If the hole deviates from the center of the die, the material will be unevenly stressed during the punching process, resulting in asymmetric flanging and inability to accurately obtain the punching height. Therefore, when making a round hole, a precision alignment system (such as a laser aligner or a positioning pin) should be used to ensure accurate positioning of the round hole. At the same time, a high-precision fixture is used to fix the sheet to ensure that the sheet will not shift during the hole making and subsequent punching process.

[0045] S120, performing a hole turning test based on the hole turning diameter to obtain the hole turning edge state;

[0046] For example, the core step of the hole-flanging test is to perform flanging operations based on the hole diameter, and obtain the state of the hole edge to evaluate the forming performance of the material at this diameter. The hole-flanging test is to plastically deform the sheet material through a punch and a die of a specific diameter, and finally make the edge of the hole stand up to form a flange. During the hole-flanging process, the material in the flanging area is subjected to complex tensile, shear and compressive stresses, which will form stress concentration inside the material, especially the edge area of ​​the hole, which is more prone to cracks or tears.

[0047] S130. Based on the above-mentioned punching edge state, change the above-mentioned preset hole diameter until the above-mentioned preset hole diameter is smaller and the above-mentioned punching edge state is crack-free, and determine the punching height corresponding to the punching product as the limit punching height corresponding to the current punching diameter.

[0048] Exemplarily, the hole-turning performance of the material is optimized by adjusting the aperture to find the material's limit hole-turning height. During the hole-turning process, the edge state of the material will show different stress distributions and deformation behaviors at different apertures. Therefore, by timely adjusting the aperture according to the edge state feedback, the hole-turning limit of the material can be gradually approached to ensure the optimal state of the forming performance. In this step, the edge state of the material hole-turning is used as the basis for judgment, and it is mainly observed whether cracks, wrinkles or other obvious plastic deformation failure characteristics appear at the edge of the hole-turning. If the edge state is intact, the preset aperture can be gradually reduced to further approach the material's limit hole-turning capacity; conversely, if defects such as cracks appear at the edge, the aperture needs to be increased to avoid material failure.

[0049] For example, the evaluation of the maximum hole height is a key goal in the hole-turning test, that is, to find the maximum hole-turning height that the material can reach under the condition of the minimum preset hole diameter and no cracks on the hole edge. The core principle of this step is to test the hole-turning ability of the material by continuously reducing the preset hole diameter until cracks appear on the edge, indicating that the material has exceeded its maximum hole-turning height. The crack-free hole-turning state means that the material has good forming performance at this hole diameter and can reach the maximum hole-turning height without failure.

[0050] In summary, the embodiment of the present invention provides a method for testing the ultimate hole-turning height of high-strength steel. By adopting multiple hole-turning experiments and gradually adjusting the hole diameter and the hole-turning height, the ultimate hole-turning height under different hole-turning diameters can be accurately grasped. During the experiment, the hole diameter is gradually reduced or increased until the current hole-turning height is obtained when there is no crack on the edge of the hole. At the same time, this method can significantly reduce the material cracking during the hole-turning process, improve the overall quality of the material during the hole-turning forming process, and ensure the safety and stability of the product. The present invention is suitable for a variety of hole-turning processing technologies, including punching, wire cutting, laser cutting, etc., and has strong process adaptability.

[0051] Taking the high-strength pickled steel plate HR800CP raw material processed into a specimen with a size of 300mm×300mm and a turned hole as an example, this application is described in detail:

[0052] For example, the high-strength steel sheet to be tested is placed on the die, and a circular hole with a predetermined aperture (15 mm) is made in the center area of ​​the die. Next, the sheet with the circular hole is placed on the punching die, ensuring that the circular hole on the sheet is coaxial with the center of the die. Figure 2 As shown, ① is the punch for flanging holes, ② is the die for flanging holes, ③ are the positioning rings for the punch and die, and ④ is the pressing plate for flanging holes.

[0053] Select a punch structure mold with a hole diameter of 20mm, start the press, and close the pressure plate and the die. Its function is to fix the sheet material so that the center hole of the sheet material is concentric with the center axis of its mold. Then the punch flips the sheet material to complete the hole flipping test process; confirm whether there are cracks on the edge of the hole flipping. If there are no cracks, reduce the predetermined aperture of the original circular hole, repeat the above hole flipping process, and then observe whether there are cracks on the edge of the hole flipping. Conversely, if there are cracks, enlarge the diameter of the circular hole and repeat the hole flipping action. Until the limit hole flipping height under this hole flipping diameter is obtained, the hole making diameter is 14mm and the hole flipping is 2.5mm; finally, the hole flipping diameter is continuously changed to obtain the limit hole flipping height value under different hole flipping diameters. The punch diameter in the hole flipping mold is selected as 40mm, 60mm, 80mm, 100mm, 150mm, 200mm and other apertures. The maximum punching heights are 5.0mm, 7.5mm, 10.0mm, 12.5mm, 15.7mm, and 17.6mm. By connecting the various limit values ​​in the coordinate system, the maximum punching height curves for different punching diameters of the material are obtained. Figure 3 shown.

[0054] In some embodiments, the radius of the top corner of the punch is greater than or equal to 5 mm;

[0055] For example, the fillet design of the punch top directly affects the stress distribution at the edge of the material during the punching process. When the fillet radius is small, the material will experience greater stress concentration during the punching process, especially in the transition area of ​​the fillet, which is prone to local cracks or failure. By increasing the fillet radius of the punch, the stress distribution of the material in this area becomes more uniform, reducing the risk of material cracking.

[0056] When the fillet radius is larger, the material can transition more smoothly from a flat state to a vertical state during the punching process. A larger fillet allows the material to flow more evenly during the punching process, thereby reducing the strain rate and reducing the possibility of edge tearing. Especially in the forming process of high-strength materials, a larger fillet radius can effectively delay the formation of cracks and improve the overall forming performance. A larger fillet radius can also reduce the friction between the punch and the material. A smaller fillet radius may increase the contact area between the material and the die, resulting in greater friction during the punching process, thereby increasing the stress load on the material. An increase in the fillet radius helps reduce the friction effect and make the punching process smoother.

[0057] In some examples, the above-mentioned changing the preset aperture based on the above-mentioned hole edge state includes:

[0058] When the edge of the hole is crack-free, the preset diameter of the circular hole is reduced;

[0059] When the edge of the punched hole is cracked, the preset hole diameter of the circular hole is increased.

[0060] Exemplary hole diameter adjustment in a crack-free state includes:

[0061] When the edge of the flanging hole is tested and confirmed to be free of cracks, it means that the material has not yet reached its plastic limit. At this time, the material in the flanging area still has a large deformation capacity and can withstand greater plastic deformation. Therefore, consider further reducing the preset hole diameter, thereby increasing the material's flanging height in the next flanging test.

[0062] Reduce the preset aperture. Reducing the aperture can increase the height of the hole, but it will also increase the stress on the edge area. Therefore, in the process of reducing the aperture, it needs to be done step by step, and the amount of each reduction should be controlled within a certain range (for example, between 0.5mm and 1mm) to ensure that the stress will not suddenly increase and cause the material to rupture. After each reduction in the aperture, a hole-turning test is required, and the state of the hole-turning edge is checked again. As long as there is still no crack on the edge, the aperture can continue to be reduced until the material reaches its limit hole-turning height. This process of gradually reducing the aperture can gradually approach the forming limit of the material and ensure the accuracy and stability of the test data.

[0063] Aperture adjustment when cracks appear, including:

[0064] When cracks appear on the edge of the punched hole, it indicates that the punched hole deformation of the material has reached or exceeded its tolerance limit. Cracks are usually caused by excessive local stress in the material, which exceeds the plastic limit of the material. Therefore, when cracks appear, it is necessary to immediately stop reducing the hole diameter and instead increase the preset hole diameter appropriately to reduce the stress generated during the punching process.

[0065] If cracks, tears or severe plastic deformation appear on the edge of the punch hole, it means that the material has approached or exceeded its punch hole limit height. At this time, the hole diameter should be increased to reduce the deformation of the material. The amplitude of the increase in the hole diameter should be moderate (for example, increase by 1mm to 2mm) so that when the crack disappears, the material's limit punch hole height can be gradually approached.

[0066] After increasing the hole diameter and observing that the crack disappears, perform the hole turning test again and check the edge state of the material. If the crack does not reappear, it is confirmed that the material forming performance is good under the current hole diameter. At this time, the hole diameter can be gradually reduced and the test process under the crack-free state can be re-entered until the limit hole turning height is approached again.

[0067] In some examples, this also includes:

[0068] Changing the above-mentioned hole turning diameter to obtain the corresponding limit hole turning height under different above-mentioned hole turning diameters;

[0069] Curve fitting is performed based on all the tested hole turning diameters and their corresponding limit hole turning heights to obtain the limit hole turning height curve.

[0070] For example, in the punching forming experiment, the punching diameter directly affects the punching performance of the material, and the limit punching height under different punching diameters reflects the forming limit of the material under specific conditions. By systematically changing the punching diameter and testing the corresponding limit punching height, a series of matching data of diameter and height can be obtained.

[0071] In order to better understand the punching behavior of materials under different conditions, the experiment should not only obtain the limit punching height under a single punching diameter, but also conduct punching tests based on multiple diameters. Then, by curve fitting all the test data, a curve reflecting the punching limit of the material can be obtained, which is called the limit punching height curve. This curve can be used to predict the forming limit under other untested diameters, or for process optimization and mold design.

[0072] In some examples, this also includes:

[0073] The above-mentioned hole-turning diameter is achieved by changing the outer diameter of the hole-turning punch, the inner diameter of the hole-turning die and the inner diameter of the positioning rings of the punch and die.

[0074] Exemplarily, the hole diameter refers to the diameter of the hole formed by the hole-bursting operation. In the stamping or hole-bursting process, the hole diameter is the size of the final hole. The outer diameter of the hole-bursting punch, the punch is the part of the mold that pushes the material when the hole is burred. The outer diameter of the punch determines the shape of the material pushed or punched out during the hole-bursting process. Therefore, by increasing or decreasing the outer diameter of the punch, the size of the hole after the hole is burred can be directly affected. The inner diameter of the hole-bursting die, the die is a part that cooperates with the punch, used to support the material and provide the punch with space for forming. The inner diameter of the die is the part that the punch enters, which directly affects the final size of the material hole. The inner diameter of the locating ring of the punch and die, the locating ring is used to maintain the centering and position between the punch and the die to ensure the accuracy of the hole-bursting process. Its inner diameter will also affect the accuracy and size of the hole.

[0075] The punch is a key forming tool in the mold, and its outer diameter directly determines the size of the hole after the material is punched. The punch pushes the edge of the material during the punching process to form a vertical flange. Therefore, the larger the outer diameter of the punch, the larger the hole diameter formed by the punching; conversely, the smaller the outer diameter of the punch, the higher the degree of the material's punching and the greater the punching height, but the greater the force on the material, and the increased risk of cracks. The punching diameter can be changed by replacing punches with different outer diameters. Usually, the outer diameter of the punch varies widely, ranging from 20mm to 200mm, depending on the range of punching diameters required for the experiment. Each time the punch is replaced, it is necessary to ensure that its outer diameter is highly accurate to ensure the repeatability and accuracy of the experimental results.

[0076] The punching die provides support for the material to be punched, and its inner diameter determines the space formed by the material during the punching process. The inner diameter of the die is used in conjunction with the outer diameter of the punch to ensure that the material does not move or warp when subjected to force. When the inner diameter of the die is large, the difficulty of punching is relatively low, and the punching height of the material is small; when the inner diameter of the die is small, the support of the edge of the material is reduced, the punching height increases, and the risk of cracks also increases. The support conditions for punching can be adjusted by replacing dies with different inner diameters. Precise control of the inner diameter of the die is essential to ensure uniform forming of the material during the punching process, especially in the punching experiment of high-strength materials, the support of the die must maintain the stability of the material. The inner diameter of the die generally maintains a certain gap with the outer diameter of the punch. This gap is usually set to 1.1 to 1.3 times the thickness of the material to ensure smooth flow during the forming process. A smaller inner diameter of the die increases the punching height because it limits the expansion space of the material, causing the edge of the material to be subjected to greater deformation. This may lead to stress concentration at the edge of the material and increase the possibility of cracks. Therefore, when designing the inner diameter of the die, the most appropriate size must be selected based on the material's hole-turning performance and forming requirements.

[0077] The locating rings of the punch and die are used to ensure that the punch and die are aligned during the hole-turning process to avoid misalignment or offset between the dies. The inner diameter of the locating ring affects the accuracy of the hole-turning process. If the inner diameter of the locating ring is too large, the fit between the dies may deviate, resulting in asymmetric hole-turning or uneven force on the edges; if the inner diameter is too small, the mold fit is too tight, which may affect the smoothness of the forming. By changing the inner diameter of the locating ring, the alignment between the punch and die during the hole-turning process can be fine-tuned, thereby improving the forming quality of the material. Precise control of the inner diameter of the locating ring helps to ensure concentricity during the hole-turning process and improve the forming accuracy of the hole-turning, which is particularly important in high-precision processes. The adjustment of the inner diameter of the locating ring is usually to match the specific hole-turning diameter and material properties to ensure that the mold system can maintain a stable fit during operation.

[0078] In some examples, this also includes:

[0079] The final preset hole diameter corresponding to the punching product with the maximum punching height under the first punching diameter is determined as the starting experimental hole diameter of the current punching diameter, wherein the above-mentioned first punching diameter is the punching diameter with the smaller difference with the above-mentioned current punching diameter among the punching diameters that have been tested.

[0080] For example, in the hole turning experiment, it is a common method to gradually approach the material's limit hole turning height through multiple iterations. However, starting each experiment from the same preset aperture will significantly increase the number and time of experiments. Therefore, according to the experimental results of the previous hole turning diameter, determining the starting experimental aperture of the current hole turning diameter can greatly improve the experimental efficiency. The core content is to select the experimental data with the smallest difference between the previous hole turning diameter and the current hole turning diameter, and use the final hole making diameter corresponding to its limit hole turning height as the starting aperture of the next experiment. This can avoid unnecessary redundant experiments and directly enter the critical test interval.

[0081] In the hole punching experiment, the hole punching heights of different diameters often have a certain correlation. The hole punching height of a smaller diameter can usually be used as a reference for the hole punching of a larger diameter, because the material's forming performance is close to the limit at a smaller diameter. By analyzing the experimental data, it can be found that as the hole punching diameter increases, the hole punching height will gradually increase, but the amplitude of each increase tends to be gentle. Therefore, using the limit height of the previous hole punching diameter as the starting point of the current experiment can speed up the experimental process.

[0082] In order to ensure that the selected starting hole diameter is closest to the current experimental requirements, the minimum difference rule is usually adopted, that is, among the hole turning diameters that have completed the experiment, the diameter with the smallest difference with the current hole turning diameter is selected. For example, in the hole turning experiment, the experiments of 20mm and 40mm hole turning diameters have been completed, and the following data have been obtained. When the hole turning diameter is 20mm, the hole turning limit height is 2.5mm, and the preset final hole diameter is 14mm; when the hole turning diameter is 40mm, the hole turning limit height is 5.0mm, and the preset final hole diameter is 16mm; now it is necessary to test the limit hole turning height of 60mm hole turning diameter. According to the above data, the difference between 40mm diameter and 60mm is the smallest (20mm), so the 40mm experimental data is selected as the starting point of this 60mm experiment, and the final 16mm preset hole diameter in the 40mm hole turning diameter experiment is used as the starting hole diameter of this experiment.

[0083] In some examples,

[0084] The difference between the iterative experimental aperture and the above-mentioned initial experimental aperture is a preset integer multiple of the iterative increase step size;

[0085] In the case where the current hole punching diameter is greater than the first hole punching diameter, the preset integer multiple is a positive integer;

[0086] In the case where the current punching diameter is smaller than the first punching diameter, the preset integer multiple is a negative integer.

[0087] For example, in order to improve the experimental efficiency and ensure the accuracy of the results, it is a very effective strategy to iteratively adjust the aperture using integer multiples of a preset step length. Specifically, when the current hole turning diameter is larger than the previous hole turning diameter, the step length is adjusted to a positive integer multiple, that is, the aperture gradually increases; when the current hole turning diameter is smaller than the previous hole turning diameter, the step length is adjusted to a negative integer multiple, that is, the aperture gradually decreases.

[0088] When the current hole diameter is larger than the previous hole diameter, the hole height tends to increase. At this time, it is necessary to gradually increase the test aperture by positive integer multiples to ensure that the force distribution at the edge of the material is relatively uniform and prevent the sudden appearance of cracks. For example, assuming that in the extreme hole height experiment under a hole diameter of 40mm, the final experimental aperture is determined to be 16mm, and the current hole diameter experiment of 60mm is to be carried out (if 60mm is greater than 40mm), the test aperture can be started from 16mm aperture and gradually increased by integer multiples of 1mm or 2mm each time until cracks or other failure phenomena appear at the edge of the hole.

[0089] When the current hole turning diameter is smaller than the previous hole turning diameter, the hole turning height will be reduced. In order to accurately determine the limit hole turning height, the experimental aperture can be gradually reduced by negative integer multiples. For example, assuming that the experimental aperture under the hole turning diameter of 60mm is 18mm, and the current hole turning experiment with a diameter of 40mm is to be carried out, the aperture can be reduced from 18mm and the aperture can be reduced by negative integer multiples of 1mm or 2mm to gradually approach the limit height of the hole turning diameter of 40mm.

[0090] The choice of step size is crucial for experimental efficiency and accuracy. The step size is selected according to the characteristics of the material. For high-strength materials, a smaller step size (such as 1mm or 0.5mm) is more appropriate to accurately find the limit hole height; for softer materials, a slightly larger step size (such as 2mm) can be used to speed up the experimental process. During the experiment, the positive integer step size is used to gradually increase the hole diameter to ensure that the material can reach a higher hole height in a crack-free state; the negative integer step size is used to gradually reduce the hole diameter to ensure that the material can accurately approach the limit hole condition. The choice of positive and negative integers depends on the size relationship between the current hole diameter and the previous experimental diameter. The adjustment of the step size should follow the principle of continuity to avoid a sudden and large increase or decrease in the hole diameter during the experiment. Large adjustments may cause the material to suddenly enter a failure state during the hole-turning process, increasing the uncertainty of the experiment. Through step-by-step iteration, the hole-turning process of the material can be more accurately controlled to ensure the repeatability of the experimental results.

[0091] In some examples,

[0092] When the above-mentioned hole turning diameter is within the first interval, the growth rate of the above-mentioned limit hole turning height changes linearly;

[0093] When the drilling diameter is within the second interval, the growth rate of the limit drilling height changes nonlinearly.

[0094] For example, in the punching experiment, as the punching diameter changes, the material's limit punching height often shows different growth patterns. According to the experiment, the punching diameter can be divided into two intervals, and the growth law of the limit punching height can be analyzed according to the characteristics of each interval; the first interval is a smaller punching diameter range, and the growth rate of the limit punching height changes linearly, that is, as the punching diameter increases, the punching height increases at a fixed rate. The second interval is a larger punching diameter range, and the growth rate of the limit punching height shows a nonlinear change, that is, when the punching diameter increases, the growth rate of the punching height gradually slows down, showing nonlinear characteristics.

[0095] In the first range, the hole diameter is usually small, and the hole height of the material increases linearly with the increase of the diameter. This is because at a smaller hole diameter, the deformation degree of the material is lower, the tensile stress at the edge is relatively small, and the material can be plastically deformed in a more uniform manner, resulting in a basically constant ratio between the hole height and the diameter.

[0096] In the second interval, when the hole diameter reaches a certain value, the growth of the limit hole height is no longer linear, but shows a nonlinear change. In the process of hole punching with a larger diameter, the edge of the material is subjected to greater stress, and the increase in the hole height gradually tends to be gentle. This is because the behavior of the material near the limit plastic deformation becomes more complicated, and stress concentration or local deformation is prone to occur during the hole punching process, which makes the growth rate of the hole height gradually decrease.

[0097] In the embodiment of the present application, the first interval range can be set to a hole diameter less than or equal to 100 mm, and the second interval range can be set to a hole diameter greater than 100 mm.

[0098] See also Figure 4 , which is a schematic diagram of a structure of a testing device for the limit hole-turning height of high-strength steel provided in an embodiment of the present application, comprising:

[0099] The aperture setting unit 21 is used to make a circular hole of a preset aperture at the center of the sheet to be tested;

[0100] A state acquisition unit 22, used to perform a hole turning test based on the hole turning diameter to obtain a hole turning edge state;

[0101] The height determination unit 23 is used to change the preset hole diameter based on the above-mentioned hole edge state until the preset hole diameter is smaller and the above-mentioned hole edge state is crack-free, and the hole height corresponding to the hole-punching product is determined as the limit hole height corresponding to the current hole-punching diameter.

[0102] See also Figure 5 The embodiment of the present application also provides an electronic device 300, including a memory 310, a processor 320, and a computer program 311 stored in the memory 310 and executable on the processor. When the processor 320 executes the computer program 311, the steps of any one of the above-mentioned methods for testing the limit hole-turning height of high-strength steel are implemented.

[0103] Since the electronic device introduced in this embodiment is a device used to implement a high-strength steel limit hole-turning height testing device in the embodiment of the present application, based on the method introduced in the embodiment of the present application, the technical personnel in this field can understand the specific implementation mode of the electronic device of this embodiment and its various variations. Therefore, how the electronic device implements the method in the embodiment of the present application is not introduced in detail here. As long as the equipment used by the technical personnel in this field to implement the method in the embodiment of the present application is within the scope of protection of this application.

[0104] During the specific implementation process, when the computer program 311 is executed by a processor, any implementation method in the embodiments corresponding to the first aspect can be implemented.

[0105] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0106] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-readable program code.

[0107] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0108] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0109] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0110] The present application also provides a computer program product, which includes computer software instructions. When the computer software instructions are executed on a processing device, the processing device executes Figure 1 A process of a method for testing the ultimate hole-turning height of high-strength steel in a corresponding embodiment.

[0111] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a server or a data center that includes one or more available media integration. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state drive (SSD)), etc.

[0112] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0113] In the several embodiments provided in the present application, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0114] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0115] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0116] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0117] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

[0118] Although the preferred embodiments of this specification have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of this specification.

[0119] Obviously, those skilled in the art can make various changes and modifications to this specification without departing from the spirit and scope of this specification. Thus, if these modifications and variations of this specification fall within the scope of the claims of this specification and their equivalents, this specification is also intended to include these modifications and variations.

Claims

1. A method for testing the limit hole height of high-strength steel, characterized in that: include: Make a circular hole of preset diameter in the center of the sheet to be tested; Perform a hole turning test based on the hole turning diameter to obtain the edge status of the hole turning; Based on the state of the punching edge, the preset hole diameter is changed until the preset hole diameter is smaller and the state of the punching edge is crack-free, and the punching height corresponding to the punching product is determined as the limit punching height corresponding to the current punching diameter.

2. The method for testing the limit hole height of high-strength steel according to claim 1, characterized in that: The changing the preset aperture based on the state of the hole-turning edge includes: When the edge of the hole is crack-free, reducing the preset diameter of the circular hole; When the edge of the punched hole is cracked, the preset hole diameter of the circular hole is increased.

3. The method for testing the limit hole height of high-strength steel according to claim 1, characterized in that: Also includes: Changing the hole-turning diameter to obtain the corresponding limit hole-turning height under different hole-turning diameters; Curve fitting is performed based on all the tested hole turning diameters and their corresponding limit hole turning heights to obtain the limit hole turning height curve.

4. The method for testing the limit hole height of high-strength steel according to claim 3, characterized in that: The hole-bursting diameter is achieved by changing the outer diameter of the hole-bursting punch, the inner diameter of the hole-bursting die and the inner diameter of the positioning rings of the punch and die.

5. The method for testing the limit hole height of high-strength steel according to claim 3, characterized in that: Also includes: The final preset hole diameter corresponding to the punching product with the maximum punching height under the first punching diameter is determined as the starting experimental hole diameter of the current punching diameter, wherein the first punching diameter is the punching diameter with the smaller difference with the current punching diameter among the experimental punching diameters.

6. The method for testing the limit hole height of high-strength steel according to claim 5, characterized in that: The difference between the iterative experimental aperture and the initial experimental aperture is a preset integer multiple of the iterative increase step size; In the case where the current hole turning diameter is greater than the first hole turning diameter, the preset integer multiple is a positive integer; In the case where the current punching diameter is smaller than the first punching diameter, the preset integer multiple is a negative integer.

7. The method for testing the limit hole height of high-strength steel according to claim 3, characterized in that: When the hole turning diameter is within the first interval, the growth rate of the limit hole turning height changes linearly; When the drilling diameter is within the second interval, the growth rate of the limit drilling height changes nonlinearly.

8. A device for testing the limit hole height of high-strength steel, characterized in that: include: Aperture setting unit, used to make a circular hole of preset aperture in the center of the sheet to be tested; A state acquisition unit, used for performing a hole turning test based on the hole turning diameter to obtain the hole turning edge state; The height determination unit is used to change the preset hole diameter based on the hole edge state until the preset hole diameter is smaller and the hole edge state is crack-free, and the hole height corresponding to the hole product is determined as the limit hole height corresponding to the current hole diameter.

9. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor is used to implement the steps of a method for testing the limit hole-turning height of high-strength steel as described in any one of claims 1 to 7 when executing the computer program stored in the memory.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, a method for testing the limit punching height of high-strength steel is implemented as described in any one of claims 1 to 7.

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