Mechanical property determination method and force measuring system

Abstract

The invention provides a mechanical property determination method and a force measurement system, and belongs to the technical field of mechanical property detection.The method comprises the steps that data collected in the blanking operation process of a test board is obtained, and the data at least comprises a data acquisition module; the maximum blanking force and / or feature data of residual pieces or punched holes obtained by blanking operation on the test plate; and inputting the data into the target mechanical property analysis model to obtain the tensile strength and / or the elongation at break of the tested plate. Compared with a tensile test, the blanking operation can be directly performed on the test plate, so that the operation is simple; when one or a few holes are punched in the test plate, the shape and the size of the punched holes are not specially limited, so that a proper punching position can be selected, and the test plate cannot be scrapped; when the mechanical property of each area of the test plate needs to be accurately obtained, a plurality of dense punched holes can be punched in the test plate, so that the overall mechanical property of the large casting can be reflected relatively more accurately.

Description

Technical Field

[0001] The present application belongs to the technical field of mechanical property detection, and in particular relates to a method for determining mechanical properties and a force measurement system. Background Art

[0002] Currently, the industry evaluates the mechanical properties of large castings through physical sampling. Specifically, this involves cutting standard tensile specimens from the planar area of ​​the large casting, and using the experimental data from the tensile specimens to represent the average mechanical properties of the material in that area. However, there are the following problems: First, cutting standard tensile specimens from the planar area of ​​a large casting is complex; second, cutting standard tensile specimens from the planar area of ​​a large casting can damage the test plate, causing it to be scrapped; third, when cutting multiple tensile specimens from a large casting, the density of the tensile specimens is relatively small due to the standard size requirements. Since the mechanical properties of large castings fluctuate to a certain extent in different areas, cutting tensile specimens with a relatively small density makes it impossible to accurately determine the mechanical properties of each area of ​​the large casting. Summary of the Invention

[0003] The purpose of the embodiments of the present application is to provide a method for determining mechanical properties and a force measurement system to solve the technical problem in the prior art that when standard tensile specimens are cut from a planar area of ​​a large casting to evaluate the mechanical properties of the large casting, the density of the tensile specimens is relatively small due to the requirements of the standard size of the tensile specimens, making it impossible to accurately determine the mechanical properties of each area of ​​the large casting.

[0004] To achieve the above objectives, the technical solution adopted in this application is:

[0005] The first aspect of the present application provides a method for determining mechanical properties, comprising:

[0006] Acquire data collected during the blanking operation of the test plate, the data at least including:

[0007] Maximum blanking force, and / or characteristic data of the fragments or punched holes obtained by the blanking operation on the test sheet;

[0008] The data are input into the target mechanical properties analysis model to obtain the tensile strength and / or elongation at break of the test plate.

[0009] In some implementations, the target mechanical property analysis model includes a target tensile strength analysis model, wherein: at least the maximum blanking force is an independent variable of the target tensile strength analysis model, and the tensile strength is a dependent variable of the target tensile strength analysis model, and / or,

[0010] The characteristic data includes at least one of a rounded corner band, a bright band, a fracture band and a burr, and the target mechanical property analysis model includes a target fracture elongation analysis model, wherein: at least one of the rounded corner band, the bright band, the fracture band and the burr is an independent variable of the target fracture elongation analysis model, and the fracture elongation is a dependent variable of the target fracture elongation analysis model.

[0011] In some implementations, the method further includes: obtaining test data of multiple different specimens, the test data of any specimen including the tensile data of the specimen collected when a standard tensile test is performed on the specimen and the blanking data of the specimen collected when a blanking test is performed on any specimen, wherein the tensile data includes tensile strength and / or elongation at break, and the blanking data includes at least one of maximum blanking force, fillet band, bright band, fracture band and burr; determining the relationship between the independent variable and the dependent variable of the same specimen based on the test data of multiple different specimens, the dependent variable being the tensile data of the specimen, and the independent variable being the blanking data of the specimen; fitting the relationship between the independent variable and the dependent variable of multiple different specimens to obtain a target mechanical property analysis model.

[0012] In some implementations, when the specimen is a sheet material formed by rolling or extrusion, a standard tensile test and a punching and sheeting test are performed on the same specimen, specifically including: the specimen is in the shape of a standard tensile specimen, and a punching and sheeting test is first performed on the position near the end of the specimen, and then the standard tensile test is performed on the specimen.

[0013] In some implementations, when the sample is a cast plate, a standard tensile test and a punching and sheeting test are performed on the same sample, specifically including: cutting the sample to prepare a standard tensile sample, the length direction of the standard tensile sample is along a first direction, the first direction is the direction from the sample close to the casting hole to the direction away from the casting hole when the sample is cast, and after completing the preparation of the standard tensile sample, a standard tensile test is performed on the standard tensile sample; performing a punching and sheeting test on the sample, and the position of the punching and sheeting test is located on one side of the position when the standard tensile sample is cut along a second direction, and is close to the middle position when the standard tensile sample is cut, wherein the second direction is perpendicular to the first direction.

[0014] In some implementations, the method includes: in the same sample, the obtained tensile data of the sample is used as the dependent variable, and the obtained punching and sheeting data of the sample is used as the independent variable, and the target mechanical property analysis model is obtained by fitting the relationship between the independent variables and the dependent variables of multiple different samples, including: in the same sample, the obtained tensile data of the sample is used as the dependent variable, and the obtained punching and sheeting data of the sample is used as the independent variable; the initial mechanical property analysis model is obtained by fitting the relationship between the independent variables and the dependent variables of multiple different samples; and the initial mechanical property analysis model is analyzed and verified to obtain the target mechanical property analysis model.

[0015] In some implementations, the initial mechanical property analysis model is analyzed and verified to obtain a target mechanical property analysis model, including: selecting a verification plate; inputting the blanking data obtained during a blanking test on the verification plate into the initial mechanical property analysis model to obtain calculated data; comparing the calculated data with the tensile data obtained during a standard tensile test on the verification plate; if the calculated data is not within the allowable error range, optimizing the initial mechanical property analysis model to obtain the target mechanical property analysis model; if the calculated data is within the allowable error range, using the initial mechanical property analysis model as the target mechanical property analysis model.

[0016] In some implementations, the prepared multiple samples may have the same material and molding process; or, the multiple samples may include samples with different materials and different molding processes.

[0017] In some implementations, a punching device is used to perform a punching operation on the test plate, wherein the punching device includes a punch rod, and the relationship between the diameter d of the punch rod and the thickness t of the test plate is: d≤1.5×t; and / or, the punching gap h=a×t, where a=10%~20%.

[0018] In some implementations, the collection of data on the bright band and the fracture band of the fragment includes the following: using an image acquisition device to collect a picture of the circumferential side of the fragment, wherein the image acquisition device can generate an expanded view of the entire circumferential side of the fragment; using an image measuring device to output the minimum value of the bright band, the maximum value of the bright band, the minimum value of the fracture band, and the maximum value of the fracture band; calculating the average value based on the minimum value of the bright band and the maximum value of the bright band to obtain the value of the bright band of the fragment, and calculating the average value based on the minimum value of the fracture band and the maximum value of the fracture band to obtain the value of the fracture band of the fragment.

[0019] A second aspect of the present application provides a force measurement system, comprising:

[0020] Analytical equipment, used to execute the method for determining mechanical properties provided by any of the above technical solutions.

[0021] In some implementations, the force measurement system may further include a punching and acquisition device for punching the test plate and for collecting data on at least one of the maximum punching force, fillet band, bright band, fracture band, and burr.

[0022] In some implementations, the punching and acquisition apparatus includes a punching device and an image acquisition unit;

[0023] The punching device includes a press, a punch rod, a die and a die base. The die is supported on the press by the die base. The punch rod is connected to the press and is arranged above the die. The die is provided with a matching hole for the punch rod to be inserted.

[0024] An installation cavity is formed in the die base, the installation cavity is communicated with the matching hole on the die, and the image acquisition part is arranged in the installation cavity.

[0025] In some implementations, the image acquisition unit includes a support shell, a support tray, and a camera. The support tray and the camera are supported on the support shell. There are multiple cameras and they are arranged in sequence along the circumferential direction of the support tray. The support tray is used to receive fragments that fall from the matching hole.

[0026] The beneficial effects of the present application are as follows: the embodiment of the present application provides a method for determining mechanical properties, which mainly adopts the method of punching to obtain experimental data of the test plate, and then brings the data into the target mechanical property analysis model provided by the embodiment of the present application, thereby obtaining the mechanical properties of the material. Since the punching operation does not require cutting the test plate to prepare a standard tensile specimen compared to the tensile test, the punching operation can be performed directly on the test plate, which is simple to operate; when punching one or a few holes in the test plate, since there is no special restriction on the shape and size of the punching holes, a suitable punching position can be selected so that the test plate will not be scrapped; when it is necessary to accurately obtain the mechanical properties of each area of ​​the test plate, a number of dense punching holes can be punched on the test plate, and when collecting the relevant data of each punching position, the mechanical properties of the corresponding area can be obtained, thereby reflecting the overall mechanical properties of the large casting relatively more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 A force-displacement graph is shown;

[0029] Figure 2 A schematic cross-sectional view of a test plate provided in an embodiment of the present application;

[0030] Figure 3 A schematic front view of a fragment provided in an embodiment of the present application;

[0031] Figure 4 This is a schematic diagram of the main view of the standard tensile specimen;

[0032] Figure 5 A schematic top view of punching holes on a test plate according to an embodiment of the present application;

[0033] Figure 6 An expanded view of the circumferential side of the fragment provided in an embodiment of the present application;

[0034] Figure 7 A schematic diagram of the cooperation between the punch rod, the die, and the test plate provided in the embodiment of the present application;

[0035] Figure 8 Flow diagram of the method for determining mechanical properties provided in the embodiments of the present application;

[0036] Figure 9 A schematic diagram of the front view of the blanking and sheeting positions on the sample provided in an embodiment of the present application;

[0037] Figure 10 A schematic diagram of the front view of the blanking and sheeting positions on a casting sample provided in an embodiment of the present application;

[0038] Figure 11 A schematic front view of a punching device provided in an embodiment of the present application;

[0039] Figure 12 A schematic diagram of the structure of the image acquisition unit provided in the embodiment of the present application;

[0040] Figure 13 A schematic diagram comparing the blanking data and standard tensile data of each test plate provided in the embodiments of the present application;

[0041] Figure 14 A graph showing the maximum blanking force and tensile strength provided in an embodiment of the present application;

[0042] Figure 15 A graph showing the average value of the fracture zone and the elongation at break provided in the embodiments of the present application;

[0043] Figure 16 A data comparison chart showing the calculated values ​​of blanking and sheeting provided in the embodiments of the present application and the measured values ​​of the standard tensile test;

[0044] Figure 17 A schematic diagram of punching out a sheet from a test plate provided in an embodiment of the present application;

[0045] Figure 18 The calculation provided in the embodiment of this application Figure 17 Data table of elongation at break at each blanking and sheeting position;

[0046] Figure 19 The calculation provided in the embodiment of this application Figure 17 Data table of tensile strength at various blanking and sheeting positions.

[0047] Among them, the reference numerals in the figures are:

[0048] 1-Test plate; 2-Standard tensile specimen; 3-Punching device; 4-Blanking and sheeting position; 5-Tensile specimen cutting position; 6-Cast specimen; 7-Image acquisition unit;

[0049] 11-punching; 12-fragment;

[0050] 111-hole fillet strip; 112-hole bright strip; 113-hole fracture strip; 114-test plate burr;

[0051] 121- fragment fillet band; 122- fragment bright band; 123- fragment fracture band; 124- fragment burr;

[0052] 21-end of the specimen; 22-middle of the specimen;

[0053] 31-punch; 32-die; 33-press;

[0054] 71 - support housing; 72 - support tray; 73 - camera; 74 - light source. DETAILED DESCRIPTION

[0055] To make the purpose, technical solutions and advantages of this application more clear, the following will further describe the implementation methods of this application in detail with reference to the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and are intended to be used to explain this application, and should not be understood as limiting this application.

[0056] In the description of this application, it should be understood that the terms "length", "width", "thickness", "top", "bottom", "inside", "outside", "up", "down", "left", "right", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0057] To facilitate the clear description of the technical solutions of this application, the words "first" and "second" are used to distinguish between identical or similar items with substantially the same functions and effects. Those skilled in the art will understand that the words "first" and "second" do not limit the quantity or order of execution, and the words "first" and "second" do not necessarily mean different.

[0058] In this application, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0059] In this application, "and / or" is simply a way to describe the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0060] It should be noted that, in this application, words such as "in one embodiment," "exemplarily," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "in one embodiment," "exemplarily," or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "in one embodiment," "exemplarily," and "for example" is intended to present the relevant concepts in a concrete manner.

[0061] Before describing the embodiments of the present application in detail, the existing relevant background is first introduced.

[0062] In the field of automobile manufacturing, in order to further simplify the manufacturing process of the body-in-white (body-in-white refers to the body without any interior and exterior decoration, dynamic force measurement system and electronic equipment installed) while improving the lightweight degree of the entire vehicle, large integrated aluminum alloy castings have gradually become an indispensable key component of current new energy vehicles. In order to avoid deformation defects caused by heat treatment of large castings, there is usually no subsequent heat treatment process when producing automotive-grade integrated large castings. The rigidity and strength requirements of large castings can be achieved by optimizing the alloy composition and adjusting the casting process. For the development of the body-in-white connection process, accurately mastering the mechanical properties of large castings is the basis for determining the selection of fasteners and the connection process parameters.

[0063] Currently, the industry evaluates the mechanical properties of large castings through physical sampling. Specifically, standard tensile specimens are cut from the flat area of ​​the large casting, and the data obtained from the tensile test on the tensile specimens represent the average mechanical properties of the material in a certain area. However, there are the following problems:

[0064] First, cutting standard tensile specimens from large flat areas of castings is a complex operation;

[0065] Secondly, cutting one or a few standard tensile specimens from a large flat area of ​​a casting will damage the test plate, which will result in the test plate being scrapped;

[0066] Furthermore, due to the heterogeneity of the mold flow state and the cooling process during the casting process, there are certain fluctuations in the mechanical properties of different areas of the large casting. Therefore, when it is necessary to accurately obtain the mechanical properties of each area of ​​the large casting, it is necessary to cut multiple tensile specimens on the large casting. However, the mechanical properties of different areas on the standard tensile specimen will also fluctuate to a certain extent. The data values ​​obtained from the tensile test of the standard tensile specimen cannot accurately reflect the mechanical conditions of each area on the standard tensile specimen. That is, when multiple tensile specimens are cut on the large casting, the density of the tensile specimens is relatively small, which makes it impossible to accurately reflect the overall mechanical properties of the large casting.

[0067] In addition, the prediction and calculation of the mechanical properties of the entire large casting area can be achieved through digital simulation or machine learning-based methods. However, since the consistency of the mechanical properties of the casting process is difficult to ensure, the performance of the final physical state of large castings generally differs from the ideal calculated working conditions.

[0068] Based on the above problems, the embodiment of the present application provides a method for determining mechanical properties, which mainly adopts the method of punching to obtain the experimental data of the test plate, and then brings the data into the mechanical model provided by the embodiment of the present application to obtain the mechanical properties of the material. Since the punching operation does not need to cut the test plate to prepare a standard tensile specimen compared to the tensile test, the punching operation can be performed directly on the test plate, which is simple to operate; when punching one or a few holes in the test plate, since there is no special limitation on the shape and size of the punching holes, a suitable punching position can be selected so that the test plate will not be scrapped; when it is necessary to accurately obtain the mechanical properties of each area of ​​the test plate, a number of dense punching holes can be punched on the test plate, and when collecting the relevant data of each punching position, the mechanical properties of the corresponding area can be obtained, and the overall mechanical properties of the large casting can be reflected relatively more accurately.

[0069] The following describes in detail the method for determining mechanical properties provided in the embodiments of the present application in conjunction with the accompanying drawings.

[0070] An embodiment of the present application provides a method for determining mechanical properties. This method is suitable for plates produced using different processes, such as rolled plates, extruded profiles, and cast plates. The material of the plates can be metal plates, such as steel plates, aluminum alloy plates, or magnesium alloy plates, etc.

[0071] The method for determining mechanical properties provided in the embodiments of the present application can be performed by an analysis device. For example, the analysis device can be an electronic device or processor with processing capabilities, or the analysis device can also be a punching device or acquisition device with processing capabilities. The acquisition device is used to collect data during the punching operation of the test plate 1.

[0072] The method includes:

[0073] Step 10: Acquire data collected during the punching operation on the test plate 1 , the data including at least the maximum punching force and / or characteristic data of the fragment 12 obtained by the punching operation on the test plate 1 .

[0074] As an example, if the analysis device and the punching device that performs the punching operation on the test plate 1 are not the same device, the analysis device can obtain data during the punching operation of the test plate 1 by the punching device from the punching device or the acquisition device.

[0075] As another example, if the analysis device and the punching device that performs the punching operation on the test plate 1 are the same device, that is, the analysis device can also perform the punching operation on the test plate 1, then the analysis device can obtain the above data during the punching operation on the test plate 1.

[0076] As another example, the data collected during the punching operation on the test plate 1 can also be input into the analysis device by the user, which is not limited in this embodiment of the present application.

[0077] Step 20: Input the data into the target mechanical property analysis model to obtain the tensile strength and / or elongation at break of the test plate 1.

[0078] As an example, the analysis device has the target mechanical property analysis model, or the target mechanical property analysis model can be deployed in a cloud server. The analysis device can interact with the cloud server to use the target mechanical property analysis model deployed in the cloud server to analyze the above data to obtain the tensile strength and / or elongation at break of the test plate 1. This embodiment of the present application is not limited to this.

[0079] When performing the punching operation on the test plate 1 , a punching device may be used. When performing the punching operation on the test plate 1 , the punching device may punch out material, and the punched out material is the fragment 12 provided in the embodiment of the present application.

[0080] Regarding the maximum blanking force, it refers to the maximum force required by the punch or punch rod to separate the material during the blanking process. As the punch or punch rod begins to cut into the material until the material is completely separated, the blanking force will gradually increase. After reaching a certain maximum value, the punch force will gradually decrease as the blanking process ends. This maximum value is the maximum blanking force. Figure 1 , which shows the force-displacement curve. Figure 1 The F1 in it represents the maximum blanking force value.

[0081] In one example, the punching device can record the force-displacement curve of the punch or punch rod during the punching operation and can output the maximum punching force, thereby allowing the user to collect the maximum punching force value. The user can input the collected maximum punching force value into the analysis equipment, thereby allowing the analysis equipment to obtain the maximum punching force value collected from the test plate 1 during the punching operation.

[0082] In one example, the feature data includes at least one of a rounded corner band, a bright band, a broken band, and a burr.

[0083] When the punching device is used to perform a punching operation on the test plate 1, a punching hole 11 is formed on the test plate 1. The hole wall surface of the punching hole 11 can be called a punching section. Figure 2 The punching cross section usually includes three areas, namely the hole fillet band 111, the hole bright band 112 and the hole fracture band 113. The hole fillet band 111 is formed at the beginning of plastic deformation in the blanking process due to the bending and stretching of the metal fiber. The fillet band of soft material is larger than that of hard material; the hole bright band 112 is formed when the metal undergoes plastic shear deformation in the second stage of the deformation process. It has a smooth vertical surface. The bright band of soft material is wide, and the bright band of hard material is narrow; the hole fracture band 113 is formed in the third stage of blanking. Due to the action of tensile stress, the crack continues to expand and the metal fiber is broken, so the surface is rough and not smooth, and has an inclination. In addition, burrs are usually generated during the blanking operation. Burrs refer to thin and irregular metal protrusions formed on the edge of the blanking part during the blanking process. Please refer to Figure 2 , showing the burr 114 on the test plate.

[0084] See Figure 3 , which illustrates the fragment 12 obtained when the test plate 1 is punched. Corresponding to the three areas on the punched section, the fragment 12 will have a fragment rounded corner band 121, a fragment bright band 122, and a fragment fracture band 123. At the same time, a fragment burr 124 will also be formed on the fragment 12.

[0085] In an embodiment of the present application, for the collected data related to the rounded corner band, bright band, broken band and burr, the data of the hole rounded corner band 111, the hole bright band 112, the hole broken band 113 and the test plate burr 114 can be collected on the punching section, or the data of the fragment rounded corner band 121, the fragment bright band 122, the fragment broken band 123 and the fragment burr 124 can also be collected on the fragment 12.

[0086] In the embodiments of the present application, the data includes at least maximum blanking force and / or characteristic data, and the data is input into the target mechanical properties analysis model to obtain the tensile strength and / or elongation at break of the test plate. It can be understood that one or more of the maximum blanking force, fillet band, bright band, fracture band, and burr data can be collected and brought into the mechanical properties analysis model to obtain the tensile strength or elongation at break; alternatively, two or more of the maximum blanking force, fillet band, bright band, fracture band, and burr data can be collected and brought into the target mechanical properties analysis model to obtain the tensile strength and elongation at break, respectively.

[0087] Tensile strength refers to a material's maximum ability to resist damage under a tensile load. Specifically, it is the maximum stress a material can withstand before being stretched to fracture. A specimen (processed into a specific shape and size based on the material type and relevant standards) is mounted in the testing machine fixture. A tensile force is applied to the specimen at a specified speed until it breaks, and the testing machine automatically records the force-displacement curve throughout the entire process. Elongation at break is the percentage of the elongation at break in a tensile test, divided by the original gauge length. It is an important indicator of a material's plastic deformation capacity. Similar to the tensile strength test, it is usually performed on a universal testing machine. A processed standard specimen is mounted on the machine and stretched at a specified speed until it breaks. The testing machine records the elongation at break and calculates the elongation at break using a formula. When performing a tensile test on a universal testing machine, both the tensile strength and elongation at break of a standard tensile specimen can be measured simultaneously.

[0088] When measuring the tensile strength and elongation at break of the test plate 1 using a universal testing machine, it is necessary to first cut a standard tensile specimen 2 from the test plate 1, which is a cumbersome operation. However, the embodiment of the present application can perform a punching operation directly on the test plate 1, and there is no need to cut the test plate 1 to prepare the standard tensile specimen 2, which is a simple operation.

[0089] See Figure 4, which illustrates a standard tensile specimen 2 of a certain shape. Since the standard tensile specimen 2 requires a specific shape, cutting the standard tensile specimen 2 on the test plate 1 will cause the test plate 1 to be scrapped and unusable. However, in the embodiment of the present application, only the test plate 1 needs to be punched, and the shape and size of the punching holes 11 are not particularly limited. For example, one or a few small holes that do not affect the overall shape and mechanical properties of the test plate 1 can be punched. Alternatively, some parts usually require holes to be machined, and punching can be used to process the holes at the locations where they need to be machined, and data can be collected. This allows the tensile strength and / or elongation at break to be obtained using the collected data using a mechanical properties analysis model while meeting the hole machining requirements for the test plate 1.

[0090] It is worth noting that rolled sheet materials and extruded profiles have good consistency in mechanical properties. Therefore, when the test sheet 1 is a rolled sheet material or an extruded profile, one or a small number of holes can be punched in the test sheet 1 to evaluate the tensile strength and / or elongation at break of the test sheet 1. The small number here can refer to two, three, four, etc.

[0091] For large castings, the forming process causes fluctuations in the mechanical properties of different regions. When cutting standard tensile specimens 2 from large castings, the size requirements of standard tensile specimens 2 result in a relatively small number of standard tensile specimens 2 being produced on the large casting. Furthermore, using a testing machine on a standard tensile specimen 2 can only yield a single tensile strength value and a single elongation at break value. However, the mechanical properties of different regions on the standard tensile specimen 2 fluctuate to a certain extent, meaning that a single value cannot accurately reflect the mechanical conditions of each region on the standard tensile specimen 2. Therefore, cutting standard tensile specimens 2 from large castings cannot accurately reflect the mechanical properties of large castings. See [Note: The following sentences appear to be unrelated and should likely be omitted.] Figure 5 , a schematic diagram of setting a plurality of punching holes 11 on a large casting is shown. In the embodiment of the present application, there is no special limitation on the shape and size of the punching holes 11, so dense punching holes 11 can be set on the large casting, and when the relevant data of each punching operation is collected, the tensile strength and / or elongation at break of the corresponding punching position can be obtained. That is to say, the method for determining the mechanical properties provided in the embodiment of the present application can densely obtain the tensile strength and / or elongation at break of each area, thereby more accurately reflecting the overall mechanical properties of the large casting.

[0092] Furthermore, current simulation technologies generally consider the impact of large casting design, casting technology, and casting process on the mechanical properties of large castings separately, resulting in a certain deviation between simulation analysis results and the actual state. The method proposed in the embodiments of this application can directly apply to actual large casting parts, and the mechanical property results can truly reflect the actual mechanical state. In other words, the results and data obtained in the embodiments of this application are more instructive for actual production.

[0093] In one embodiment, the target mechanical property analysis model includes a target tensile strength analysis model, wherein: at least the maximum blanking force is an independent variable of the target tensile strength analysis model, and the tensile strength is a dependent variable of the target tensile strength analysis model.

[0094] The maximum blanking force is closely related to the tensile strength of the material. Generally, the higher the tensile strength of the material, the greater the maximum blanking force required for blanking. This is because the tensile strength reflects the material's ability to resist tensile failure, and the blanking process is actually the process of applying shear force to the material to separate it. The tensile strength of the material determines its ability to resist shear failure to a certain extent. Therefore, for the established target tensile strength analysis model, the maximum blanking force can be used as the independent variable of the target tensile strength analysis model, and the tensile strength can be used as the dependent variable of the target tensile strength analysis model.

[0095] In one example, in the target tensile strength analysis model, only the maximum blanking force is the independent variable of the target tensile strength analysis model, that is, when a maximum blanking force value is input, a tensile strength value can be obtained, that is, in the constructed target mechanical property analysis model, the tensile strength is only related to the maximum blanking force; in other examples, not only the maximum blanking force is the independent variable, but the independent variables in the target tensile strength analysis model can also include the diameter of the punching hole 11, the thickness of the test plate 1, and the inner diameter of the die (die 32) in the punching device 3 (the aperture of the matching hole on the die 32), etc., that is, in the constructed target mechanical property analysis model, the tensile strength is not only related to the maximum blanking force.

[0096] In the embodiment of the present application, the maximum blanking force is closely related to the tensile strength of the material, thereby ensuring the feasibility of the target tensile strength analysis model.

[0097] In one embodiment, the target mechanical property analysis model includes a target fracture elongation analysis model, wherein: at least one of the fillet band, the bright band, the fracture band and the burr is an independent variable of the target fracture elongation analysis model, and the fracture elongation is a dependent variable of the target fracture elongation analysis model.

[0098] Fillet bands, bright bands, fracture bands, and burrs have a certain relationship with elongation at break. For example, a material with a high elongation at break indicates good plastic deformation capacity, allowing it to withstand significant plastic deformation without breaking during the blanking process. As the punch descends, the material first undergoes elastic deformation under the action of the punch and die. As the punch continues downward, the material enters a stage of plastic deformation. Due to the material's high elongation at break, the plastic deformation phase lasts relatively long, allowing the material to fully flow and deform in the gap between the punch and die, forming a large bright band. Therefore, the bright band has a certain relationship with elongation at break. Since the bright band also has a relationship with fillet bands, fracture bands, and burrs, fillet bands, fracture bands, and burrs also have a certain relationship with elongation at break.

[0099] In one example, data of the debris rounded zone 121 , the debris bright zone 122 , the debris broken zone 123 , and the debris burr 124 are collected on the debris 12 .

[0100] In one example, in the target fracture elongation analysis model, there is only one independent variable and the independent variable is any one of the fragment rounded band 121, the fragment bright band 122, the fragment fracture band 123 and the fragment burr 124. For example, in the target fracture elongation analysis model, the fragment bright band 122 or the fragment fracture band 123 is the independent variable.

[0101] In one example, in the target fracture elongation analysis model, at least two of the debris rounded corner band 121, the debris bright band 122, the debris fracture band 123 and the debris burr 124 are independent variables, for example, the debris bright band 122 and the debris fracture band 123 are independent variables.

[0102] In one example, in the target fracture elongation analysis model, when there are more than two independent variables, some of the independent variables are one of the fragment rounded band 121, the fragment bright band 122, the fragment fracture band 123 and the fragment burr 124, and the other independent variables are the diameter of the punching 11, the thickness of the test plate 1 and the inner diameter of the die (die 32) in the punching device 3.

[0103] In the embodiment of the present application, the fillet band, the bright band, the fracture band and the burr have a certain relationship with the elongation at fracture, thereby ensuring the feasibility of the target elongation at fracture analysis model.

[0104] In one embodiment, the collection of data on fillet bands, bright bands, broken bands, and burrs includes the following:

[0105] Using an image acquisition device to capture a picture of the circumferential side of the fragment 12, wherein the image acquisition device can also generate an expanded view of the entire circumferential side of the fragment 12;

[0106] The image measuring device is used to output the data of the debris rounded corner zone 121, the debris bright zone 122, the debris broken zone 123 and the debris burr 124 in the unfolded image.

[0107] It's worth noting that for the four parameters of fillet band, glossy band, fracture band, and burr, the image measurement device can be used to output only the required data. For example, if only the glossy band data is required, the image measurement device can be used to output the glossy band data in the expanded image. The following mainly uses the measurement of glossy band and fracture band data as an example.

[0108] In one embodiment, the values ​​of two or more bright bands in the expanded image are measured by an image measuring device, and the bright band value of the corresponding fragment 12 is obtained by averaging the values ​​of the bright bands.

[0109] See Figure 6 , which shows an expanded view of the entire circumferential side of a fragment 12, Figure 6 D1 and D2 are used to represent the two bright band values.

[0110] In one example, two bright band values ​​in the expanded image are measured with the help of an image measuring device. The two bright band values ​​are the minimum bright band value and the maximum bright band value, respectively. The average of the minimum bright band value and the maximum bright band value is used to obtain the bright band value of the corresponding fragment 12.

[0111] In one embodiment, the values ​​of two or more fracture zones in the expanded image are measured by an image measuring device, and the fracture zone value of the corresponding fragment 12 is obtained by averaging the values ​​of the fracture zones.

[0112] See Figure 6 , which shows an expanded view of the entire circumferential side of a fragment 12, Figure 6 D3 and D4 are used to represent the values ​​of the two fault zones.

[0113] In one example, two fracture zone values ​​in the expanded image are measured with the help of an image measuring device. The two fracture zone values ​​are the minimum value and the maximum value of the fracture zone, respectively. The fracture zone value of the corresponding fragment 12 is obtained by averaging the minimum value and the maximum value of the fracture zone.

[0114] The method for collecting the bright band and fracture band data provided above is mainly obtained by measuring the fragment 12 , that is, it is convenient to measure the fragment bright band 122 and the fragment fracture band 123 on the fragment 12 .

[0115] In one embodiment, a punching device 3 is used to perform a punching operation on the test plate 1, wherein the punching device 3 includes a punch rod 31, and the relationship between the diameter d of the punch rod 31 and the thickness t of the test plate 1 is: d≤1.5×t; and / or, the punching gap h=a×t, where a=10%~20%.

[0116] See Figure 7 , schematically showing the punch 31, the test plate 1 and the die 32, Figure 7 It is shown that the diameter of the punch rod 31 is d, the thickness of the test plate 1 is t, the diameter of the die hole on the die 32 is b, and the diameter of the die hole b minus the diameter of the punch rod 31 d divided by 2 is the blanking gap h.

[0117] In the embodiment of the present application, the diameter d of the punch rod 31 and the thickness t of the test plate 1 are d≤1.5×t. For example, the diameter d of the punch rod 31 is 1.5t or 1.2t or 1.0t or 0.8t, etc.

[0118] In an embodiment of the present application, the blanking clearance h = (10% to 20%) × t, for example, the blanking clearance h = 10% × t or h = 12% × t or h = 14% × t or h = 16% × t or h = 18% × t or h = 20% × t, etc.

[0119] When the relationship between the diameter d of the punch 31 and the thickness t of the test plate 1 is d≤1.5×t, the relationship between the blanking gap h and the thickness t of the test plate 1 can continue to be defined, that is, the blanking gap h=(10%~20%)×t; alternatively, when the relationship between the diameter d of the punch 31 and the thickness t of the test plate 1 is d≤1.5×t, the relationship between the blanking gap h and the thickness t of the test plate 1 is not specifically defined. Of course, when the relationship between the blanking gap h and the thickness t of the test plate 1 is defined as h=(10%~20%)×t, the relationship between the diameter d of the punch 31 and the thickness t of the test plate 1 can be not limited to d≤1.5×t.

[0120] In the embodiment of the present application, the relationship between the diameter d of the punch rod 31 and the thickness t of the test plate 1 and / or the relationship between the blanking gap h and the thickness t of the test plate 1 is used to facilitate selection of a punch rod 31 and a die 32 of appropriate size according to the thickness of the test plate 1.

[0121] Next, the establishment of the target mechanical performance analysis model is mainly introduced.

[0122] In one embodiment, see Figure 8 , the establishment of the target mechanical performance analysis model includes the following methods:

[0123] Step S1, obtaining test data of multiple different samples, the test data of any of the samples including the tensile data of the sample collected when the standard tensile test is performed on the sample and the blanking data of the sample collected when the blanking test is performed on any of the samples, wherein the tensile data includes tensile strength and / or elongation at break, and the blanking data includes at least one of maximum blanking force, fillet band, bright band, fracture band and burr.

[0124] Specifically, multiple samples may be prepared, and a standard tensile test and a punching test may be performed on the same sample.

[0125] Next, data collection can be performed during the standard tensile test and the blanking sheet test on the same sample, that is, tensile data during the standard tensile test and blanking sheet data during the blanking sheet test are collected, wherein the tensile data include tensile strength and / or elongation at break, and the blanking sheet data include at least one of the maximum blanking force, rounded corner band, bright band, fracture band and burrs.

[0126] Step S2: Determine the relationship between the independent variable and the dependent variable of the same sample based on the test data of the multiple different samples, where the dependent variable is the tensile data of the sample and the independent variable is the blanking data of the sample.

[0127] Step S3: Fitting the relationship between the independent variables and the dependent variables of a plurality of different samples to obtain the target mechanical property analysis model.

[0128] It is worth noting that the process of establishing the target mechanical performance analysis model in the above steps S1 to S3 can be performed by the above analysis equipment. Of course, the action of establishing the target mechanical performance analysis model in the above steps S1 to S3 can also be performed by other devices other than the analysis equipment (such as a cloud server), and the embodiments of the present application do not limit this.

[0129] In the above step S1, multiple samples are prepared. It is best that the multiple samples include multiple different types of plates. The different types of plates here refer to plates with different tensile strengths and elongations at break, so that during the data collection stage, a certain range of tensile strengths and a certain range of elongations at break can be collected, which is conducive to the accuracy of the mechanical analysis model.

[0130] In multiple samples, it is best to have multiple samples of each type of board to reduce the impact of accidental errors on the test results. For example, the multiple samples include N different types of board, and each type of board includes n pieces, so the total number of samples is N×n.

[0131] For the prepared multiple samples, in one example, the materials and molding processes of the multiple samples are the same; or, in another example, the multiple samples include samples with different materials and different molding processes; or, in another example, the materials of the multiple samples are the same, but the multiple samples include different molding processes; or, in another example, the molding processes of the multiple samples are the same, but the multiple samples include different materials.

[0132] Regarding step S1 above, a standard tensile test and a blanking test are performed on the same sample. In one example, when the sample is a sheet formed by rolling or extrusion, the shape of the sample is the shape of a standard tensile sample. The blanking test is first performed on the sample near the end, and then the standard tensile test is performed on the sample. Figure 9 , indicating the blanking and taking piece position 4, which is close to the end of the sample. Figure 9 A punching experiment is carried out on the sample shown in the figure to form a sheet hole. Of course, it can also be Figure 9 Two punching and sheeting experiments were performed on the sample shown, thereby forming two sheeting holes.

[0133] It is worth noting that in Figure 9 When the illustrated sample is subjected to a tensile test, the two ends of the standard tensile sample 2 are respectively clamped on the fixtures of the testing machine. That is to say, even if a punching test is performed on the end of the standard tensile sample 2, it will not affect the subsequent tensile test on the sample.

[0134] See Figure 9 , Figure 9 The illustrated standard tensile specimen 2 includes two specimen ends 21 and a specimen middle portion 22 . The width of the specimen end portions 21 is greater than that of the specimen middle portion 22 . The specimen end portions 21 are used for punching out sheets. In an example, the length of the specimen end portions 21 is not less than 20 mm.

[0135] In this example, the sample is limited to a sheet material formed by rolling or extrusion. The metal rolling process is a processing method in which rotating rollers apply pressure to the metal blank to cause it to undergo plastic deformation, thereby obtaining a metal product with a certain shape, size and performance; the metal extrusion process is a processing method in which a metal blank in a highly plastic state is extruded from the die hole of a mold under the action of strong pressure, thereby obtaining a metal product with a specific shape and size.

[0136] The mechanical properties of the plates formed by rolling and extrusion are consistent. That is, the method provided in this example of performing a blanking test at the end of the sample and then performing a standard tensile test is suitable for plates with consistent mechanical properties. Figure 9The mechanical properties of the material at the middle position (i.e., the tensile fracture position) of the standard tensile specimen 2 are substantially the same as those at the sampling position.

[0137] In addition, it is worth mentioning that the specimen mentioned in this example is a sheet material formed by rolling or extrusion. Of course, for sheets that are not rolled or extruded but have consistent mechanical properties, the method of performing a punching test at the end of the specimen and then performing a standard tensile test can be adopted.

[0138] In step S1 above, the standard tensile test and the blanking test are performed on the same sample. In another example, when the sample is a cast plate, the sample is cut (for example, by wire cutting or water jet cutting) to prepare the standard tensile test sample 2. Figure 10 , which shows the shape of the sample when it is a cast plate. Figure 10 The sample is shown as a rectangle. Of course, the sample shape is not limited to a rectangle and can also be other shapes. For the convenience of description, when the sample is a cast plate, it is called cast sample 6. The position when cutting the standard tensile sample 2 from the cast sample 6 is called tensile sample cutting position 5. The position when punching out the cast sample 6 is called punching out position 4. Figure 10 , which illustrates the tensile specimen cutting position 5 and the punching and sheeting position 4 on the cast specimen 6.

[0139] exist Figure 10 When the cast sample 6 is cut into the standard tensile sample 2, the length direction of the tensile sample cutting position 5 is along the first direction, i.e. Figure 10 The first direction is the direction from the casting hole to the casting hole when the sample is cast. After the preparation of the standard tensile specimen 2 on the casting specimen 6 is completed, the standard tensile test can be performed on the standard tensile specimen 2. When performing the blanking test on the casting specimen 6, please refer to Figure 10 , the blanking and taking sheet position 4 of the blanking and taking sheet experiment is along the second direction (ie Figure 10 The second direction is located on one side of the tensile specimen cutting position 5 and is close to the middle position of the tensile specimen cutting position 5, wherein the second direction is perpendicular to the first direction.

[0140] Metal casting is a process in which liquid metal is poured into a mold cavity adapted to the part's shape, and then cooled and solidified to produce a part or blank. Liquid metal flows through the mold's pouring holes and flows through the cavity until it fills the cavity. Due to the varying flow patterns and cooling rates of the liquid metal in different areas of the cavity, the mechanical properties of the entire cast part may be relatively inconsistent.

[0141] For the cast sample 6, in order to make the mechanical properties of the material at the fracture position of the standard tensile specimen 2 cut out from the specimen during the standard tensile test as close as possible to the mechanical properties of the material at the punching and cutting position, taking into account the characteristics of metal casting, that is, in the direction perpendicular to the metal flow, the mechanical properties of the material are also close due to the similar cooling rate of the metal. Therefore, the length direction of the tensile specimen cutting position 5 (that is, the length direction of the standard tensile specimen 2 cut in the specimen) is set along the first direction, and the first direction is the direction from the specimen close to the casting hole to the direction away from the casting hole when the specimen is cast, and the punching and cutting position 4 is located on one side of the cutting position 5 along the second direction, and the cutting position is close to the middle position of the tensile specimen cutting position 5.

[0142] It is worth noting that, see Figure 10 , Figure 10 The diagram shows that the sheet is punched out on one side of the tensile specimen cutting position 5 , but the sheet can also be punched out on both sides of the tensile specimen cutting position 5 along the second direction.

[0143] Regarding the test data in step S1 above, when a tensile test is performed using a universal testing machine, the tensile strength and elongation at break of the sample can be output simultaneously. Depending on the requirements, both the tensile strength and elongation at break can be recorded and collected as tensile data, or only the tensile strength or elongation at break can be recorded and collected as tensile data. When a punching device 3 is used to perform a blanking and sheeting test, the punching device 3 can output the pressure-displacement curve of the punch and the maximum blanking force during the blanking operation, thereby collecting the maximum blanking force value of the sample. As for the data on the fillet band, bright band, fracture band, and burr, the data on the fragment fillet band 121, the fragment bright band 122, the fragment fracture band 123, and the fragment burr 124 on the fragment 12 can be collected. The specific collection method has been described above and will not be elaborated on here. Depending on the requirements, any one or more of the fragment fillet band 121, the fragment bright band 122, the fragment fracture band 123, and the fragment burr 124 can be collected.

[0144] Regarding steps S2 and S3, as noted above, the maximum blanking force is closely related to the tensile strength of the material. Therefore, a mechanical analysis model combining tensile strength and maximum blanking force—the target tensile strength analysis model—can be established. For the same sample, the tensile strength is used as the dependent variable, and the maximum blanking force is used as the independent variable. The target tensile strength analysis model is then obtained by fitting the tensile strength and maximum blanking force data for multiple samples. To achieve higher fitting accuracy, appropriate mathematical transformations such as reciprocal, exponential, or logarithmic transformations can be applied to the independent and dependent variables.

[0145] In one example, when establishing the target tensile strength analysis model, not only the maximum blanking force is used as an independent variable, but the independent variables in the tensile strength analysis model may also include the diameter of the punching hole 11 and / or the thickness of the test plate 1 .

[0146] It is worth noting that, see Figure 9 , which shows that two blanking experiments were carried out on one sample, that is, two maximum blanking force values ​​can be obtained on one sample, the average value of the two maximum blanking force values ​​can be calculated, and the obtained average value can be related to the tensile strength.

[0147] As noted above, fillet bands, bright bands, fracture bands, and burrs have a certain relationship with elongation at fracture. Therefore, a mechanical analysis model can be established that relates at least one of these four factors to elongation at fracture—this is known as a target elongation at fracture analysis model. For example, for the same specimen, the elongation at fracture is used as the dependent variable, and the fracture band values ​​are used as the independent variable. By fitting the elongations at fracture and the fracture band values ​​of multiple specimens, a target elongation at fracture analysis model can be obtained. To achieve higher fitting accuracy, appropriate mathematical transformations such as reciprocal, exponential, and logarithmic transformations can be performed on the independent and dependent variables.

[0148] It is worth noting that in the target fracture elongation analysis model, when the independent variable only includes the fracture zone, only the value of the fracture zone can be collected, and the values ​​of the fillet zone, bright zone and burr are not collected.

[0149] It is worth noting that in the target fracture elongation analysis model, when the independent variable only includes the fracture zone, please refer to Figure 9 , which illustrates that two punching and sheeting experiments were carried out on one sample, that is, two fracture zone values ​​can be obtained on one sample, the average value of the two fracture zone values ​​can be calculated, and the obtained average value can be related to the fracture elongation.

[0150] In one embodiment, in the same sample, the obtained tensile data of the sample is used as the dependent variable, and the obtained blanking data of the sample is used as the independent variable. The target mechanical property analysis model is obtained by fitting the relationship between the independent variable and the dependent variable of multiple different samples, including:

[0151] In the same sample, the tensile data of the sample is used as the dependent variable, and the blanking data of the sample is used as the independent variable; the initial mechanical properties analysis model is obtained by fitting the relationship between the independent variables and the dependent variables of multiple different samples;

[0152] The initial mechanical properties analysis model is analyzed and verified to obtain the target mechanical properties analysis model.

[0153] In the embodiment of the present application, a verification and analysis mechanical model link is added to verify whether the obtained target mechanical analysis model is reliable.

[0154] In one embodiment, analyzing and verifying the initial mechanical property analysis model to obtain a target mechanical property analysis model includes:

[0155] Select verification plate;

[0156] Input the blanking data obtained during the blanking experiment of the verification plate into the initial mechanical properties analysis model to obtain calculation data;

[0157] Compare the calculated data with the tensile data obtained from standard tensile tests on validation plates;

[0158] If the calculated data is not within the allowable error range, the initial mechanical properties analysis model is optimized to obtain the target mechanical properties analysis model;

[0159] If the calculated data is within the allowable error range, the initial mechanical properties analysis model will be used as the target mechanical properties analysis model.

[0160] For example, when the initial mechanical properties analysis model includes an initial tensile strength analysis model, the model can be verified after the initial tensile strength analysis model is established. If the independent variable of the initial tensile strength analysis model is the maximum blanking force and the dependent variable is the tensile strength, the specific verification and analysis process of the initial tensile strength analysis model is as follows: select a verification plate, perform a standard tensile test and a blanking test on the verification plate, bring the maximum blanking force obtained in the blanking test into the tensile strength analysis model, and compare the calculated data with the tensile strength obtained in the standard tensile test. If it is not within the allowable error range, it is necessary to continue to increase experimental data to optimize the initial tensile strength analysis model. If it is within the allowable error range, it means that the initial tensile strength analysis model can be used as the target tensile strength analysis model.

[0161] For example, when the initial mechanical properties analysis model includes an initial fracture elongation analysis model, the model can be verified after the initial fracture elongation analysis model is established. If the independent variable of the initial fracture elongation analysis model is the fracture zone and the dependent variable is the fracture elongation, the specific verification and analysis process of the initial fracture elongation analysis model is as follows: select a verification plate, perform a standard tensile test and a blanking test on the verification plate, bring the fracture zone value obtained in the blanking test into the fracture elongation analysis model, and compare the calculated data with the fracture elongation obtained in the standard tensile test. If it is not within the allowable error range, it is necessary to continue to increase experimental data to optimize the initial fracture elongation analysis model. If it is within the allowable error range, it means that the initial fracture elongation analysis model can be used as the target fracture elongation analysis model.

[0162] It is worth noting that the standard tensile test and the punching test on the verification plate can be performed respectively by referring to the method of performing the standard tensile test and the punching test on the same sample in step S1 above.

[0163] It is worth noting that the verification plate provided in the embodiment of the present application is a metal plate that has not been tested in the data collection stage.

[0164] In one example, the calculated value is compared with the experimental value obtained in the standard tensile test. If the two satisfy |calculated value - experimental value| / experimental value < 10%, they are considered to be within the allowable error range. If |calculated value - experimental value| / experimental value ≥ 10%, they are considered to be not within the allowable error range.

[0165] After the target mechanical property analysis model is obtained, a punching operation can be used to obtain experimental data and the mechanical model can be used to obtain the tensile strength and / or elongation at break of the test plate 1 .

[0166] For example, a punching operation is performed on the test plate 1 to obtain a fragment 12. The maximum punching force is recorded and the maximum punching force is substituted into the target tensile strength analysis model to obtain the tensile strength value of the test plate 1. The fracture band value of the fragment 12 is collected and substituted into the fracture elongation analysis model to obtain the fracture elongation of the test plate 1.

[0167] In one example, several punching positions may be selected on the test plate 1 , so that a tensile strength or elongation at break cloud diagram of the test plate 1 may be constructed based on the density of the punching positions.

[0168] It is worth noting that for the multiple samples mentioned in step S1, when the materials and molding processes of the multiple samples are the same, for example, the materials are all aluminum alloys and the molding processes are all casting molding, then the obtained mechanical analysis model can be limited to application on plates whose material is aluminum alloy and whose molding process is casting molding.

[0169] When multiple samples include samples of different materials and different forming processes, such as steel plates, aluminum alloy plates, magnesium alloy plates, etc., and different forming processes include casting, rolling and extrusion, the mechanical model obtained at this time is more widely used and is suitable for metal plates of various materials (such as steel plates, aluminum alloy plates, magnesium alloy plates, etc.) and metal plates of various forming processes (casting, rolling and extrusion, etc.).

[0170] It is worth noting that when the established mechanical analysis model is mainly used for a certain type of plate (i.e., the target test plate), for example, when the blanking operation is mainly used for the cast aluminum alloy plate and the mechanical model is used to obtain the tensile strength and / or elongation at break of the material, for the multiple specimens mentioned in step S1, in one example, the number of plates of the same type as the target test plate is ≥2, where the same type means that the material and forming process of the plate are the same, and the number of plates of the same type as the target test plate / the number of plates of different types from the target test plate is ≥50%.

[0171] When multiple samples are made of the same material but have different molding processes, the obtained mechanical analysis model can be limited to being applied to plates made of the same material as the samples, but the molding process of the plates is not limited.

[0172] When multiple samples have the same molding process but contain different materials, the obtained mechanical analysis model can be limited to being applied to plates with the same molding process as the samples, but the material of the plates is not limited.

[0173] An embodiment of the present application provides a force measurement system, including an analysis device, which is used to implement the method for determining mechanical properties provided in any of the above embodiments.

[0174] In one example, the analysis device includes a calculation module and an operation interface. The calculation module includes a target tensile strength analysis model and a target elongation at break analysis model. For example, by inputting a maximum blanking force into the operation interface, the analysis device can obtain the maximum blanking force and calculate the tensile strength value through the calculation module. By inputting a fracture band value into the operation interface, the analysis device can obtain the fracture band value and calculate the elongation at break through the calculation module.

[0175] In one example, the analysis device is signal-connected to the punching and collection device, and data generated by the punching and collection device can be transmitted to the analysis device.

[0176] In one example, a model of a test panel can be constructed on an analysis device, and when the maximum blanking force values ​​of multiple blanking positions of the test panel are input, the analysis device can construct a tensile strength cloud map of the test panel, and when the fracture band values ​​of multiple blanking positions of the test panel are input, the analysis device can construct a fracture elongation cloud map of the test panel.

[0177] In one embodiment, the force measuring system further comprises a punching and collecting device for punching 11 the test plate 1 and for obtaining at least one of the maximum blanking force, rounded corners, bright bands, broken bands and burrs.

[0178] It should be noted here that when establishing the mechanical analysis model provided in the embodiment of the present application, punching and collection equipment can also be used to perform punching and sheeting experiments on samples, as well as to obtain at least one of the maximum punching force, rounded corner band, bright band, fracture band and burrs.

[0179] In one example, the punching and collection equipment includes a punching device 3, which can record the force-displacement curve of the punch or punch rod 31 during the punching operation and can output the maximum punching force, thereby allowing the user to obtain the maximum punching force value.

[0180] In one example, see Figure 11 The punching device 3 includes a press 33, a punch rod 31 and a die 32. The press 33 includes a driving device, which can be a servo motor, a pneumatic cylinder or a hydraulic cylinder. The driving device is connected to the punch rod 31. The die 32 is fixed on the press 33 and is located directly below the punch rod 31. A matching hole is provided on the die 32 for the punch rod 31 to be inserted.

[0181] In one example, the driving device can provide a maximum punching pressure of no less than 50 kN.

[0182] In one example, the number of punch rods 31 and dies 32 is one set or multiple sets, and the sizes of punch rods 31 and dies 32 in different sets are different. By setting the number of punch rods 31 and dies 32 to multiple sets, punch rods 31 and dies 32 of appropriate sizes can be selected for test plates 1 of different thicknesses.

[0183] In one example, see Figure 11 The die 32 is set on the press 33 through the die base 34, and the die 32 and the die base 34 are detachably connected.

[0184] In one example, the punching and acquisition equipment also includes an image acquisition device and an image measuring device. The image acquisition device includes an image acquisition unit 7 and an image processing unit. The image acquisition unit 7 is signal-connected to the image processing unit. The image acquisition unit 7 is used to acquire image information of the circumferential side of the fragment 12. At the same time, the image processing unit is used to process the image acquired by the image acquisition unit 7. The image measuring device is used to measure the processed image and output the values ​​of the bright band and the broken band, etc.

[0185] In one example, the image acquisition unit 7 may be integrated into the punching device 3 . In other examples, the image acquisition unit 7 and the punching device 3 are independently provided.

[0186] When the image acquisition unit 7 is integrated on the punching device 3 , in one example, a mounting cavity is formed in the die base 34 , the mounting cavity is communicated with the matching hole on the die 32 , and the image acquisition unit 7 is disposed in the mounting cavity.

[0187] When using the punching device 3 to perform a punching and sheet-taking experiment, the image acquisition part 7 is first set in the mounting cavity of the die base 34, and then the test plate 1 is placed on the die 32. The punch rod 31 is controlled to move downward to punch the test plate 1. The residual pieces punched off the test plate 1 can fall onto the image acquisition part 7 through the matching holes on the die 32.

[0188] Regarding the connection method between the image acquisition part 7 and the punching device 3, in one example, a socket is provided on the circumferential side of the die base 34, the socket is connected to the installation cavity, and the image acquisition part 7 can be inserted into the installation cavity through the socket.

[0189] In one example, see Figure 12 The image acquisition unit 7 includes a support shell 71, a support tray 72 and a camera 73. The support tray 72 and the camera 73 are supported on the support shell 71. There are multiple cameras 73 and they are arranged in sequence along the circumferential direction of the support tray 72. The shooting angles of two adjacent cameras 73 overlap, so that the circumferential side of the entire test plate 1 can be completely photographed by each camera 73; the image processing unit is connected to each camera 73, and the image processing unit is used to process the images of each camera 73 to form an expanded view of the circumferential side of the test plate 1. Figure 6 , which shows a circumferential side unfolded view of the test plate 1.

[0190] The image measuring device is used to identify the circumferential side unfolded image. For example, it can identify the bright band and the fracture band. At the same time, the image measuring device can measure the values ​​of the bright band at two or more points, and the values ​​of the fracture band at two or more points. For example, the image measuring device can identify the points corresponding to the maximum value and the minimum value of the bright band, and can output the maximum value and the minimum value of the bright band. At the same time, the image measuring device can also calculate the average value of the maximum value and the minimum value of the bright band. The calculated average bright band value can be used as the bright band value of the final sample. The image measuring device can identify the points corresponding to the maximum value and the minimum value of the fracture band, and can output the maximum value and the minimum value of the fracture band. The image measuring device can also calculate the average value of the maximum value and the minimum value of the fracture band. The calculated average fracture band value can be used as the fracture band value of the final sample.

[0191] In one example, see Figure 12 A groove is formed on the top surface of the support shell 71, and the support tray 72 and the camera 73 are supported on the bottom surface of the groove. A light source 74 is arranged on the side surface of the groove to ensure that the camera 73 has a sufficiently bright environment when shooting, so as to improve the quality of the photos.

[0192] In one example, the light source 74 on the supporting shell 71 is a ring-shaped light source.

[0193] In one example, there are at least four cameras 73 , and the shooting angle of each camera 73 is greater than 90°.

[0194] The force measurement system provided in the embodiment of the present application can conveniently complete the method for determining mechanical properties, so as to obtain the tensile strength and / or elongation at break of the test plate 1.

[0195] The following is a specific example of the process of establishing the target mechanical properties analysis model based on specific experiments. It should be noted that the data given below are only for the purpose of more clearly illustrating the method of establishing the model and do not impose specific restrictions on the target mechanical properties analysis model.

[0196] (1) Prepare multiple samples and collect data

[0197] Eight samples were selected, namely steel 1, steel 2, steel 3, steel 4, steel 5, aluminum alloy 1, aluminum alloy 2, and aluminum alloy 3.

[0198] It should be noted here that the number of each sample is one or more. When the number of each sample is multiple, for example, when the number of steel material 1 is five, the tensile strength values ​​of the five steel materials 1 can be measured separately. After excluding the tensile strength values ​​that may be obviously erroneous, the average of the tensile strength values ​​can be calculated to obtain the tensile strength value of steel material 1. Similarly, the elongation at break, maximum punching force and fracture band values ​​of steel material 1 can be processed.

[0199] Steel 1, Steel 2, Steel 3, Steel 4, Steel 5 can be set to roll forming, Aluminum Alloy 1, Aluminum Alloy 2, Aluminum Alloy 3 can be set to cast forming, Steel 1, Steel 2, Steel 3, Steel 4 and Steel 5 have the shape of standard tensile specimen 2, and refer to Figure 9 First, perform blanking and sheeting tests on both ends of the sample, and then perform standard tensile tests on the sample. For aluminum alloy 1, aluminum alloy 2, and aluminum alloy 3, the shape of the sample is as follows: Figure 10 As shown, a standard tensile specimen 2 can be cut from the sample first, and then a blanking test is performed on the remaining plate, and a standard tensile test is performed on the cut standard tensile specimen 2.

[0200] Before performing the standard tensile test and the punching test on each sample, the thickness of each sample was measured and recorded.

[0201] When the sample is subjected to a standard tensile test through a testing machine, the tensile strength and elongation at break can be obtained through the testing machine, and the tensile strength and elongation at break of the sample under the standard tensile test can be collected and recorded.

[0202] When the punching and sheeting experiment is carried out, the maximum punching force of the sample can be obtained through the punching device 3, and the maximum punching force value under the punching and sheeting experiment can be collected and recorded; after the punching and sheeting experiment is carried out, the fragments 12 that fall from the sample can be obtained, and the average fracture zone value on the fragments 12 can be obtained with the help of the device, and collected and recorded as the fracture zone value of the sample.

[0203] See Figure 13 The chart shows the thickness, maximum blanking force, average fracture band, tensile strength, and elongation at break for eight different specimens. For example, Steel 1 has a thickness of 1.0 mm, a maximum blanking force of 14 kN, an average fracture band of 0.5 mm, a tensile strength of 655 MPa, and an elongation at break of 22%.

[0204] It is worth noting that when performing the blanking and sheeting test on the eight specimens, a punch 31 and die 32 of appropriate size are required. The relationship between the diameter d of the punch 31 and the thickness t of the test sheet 1 must be: d ≤ 1.5 × t, and the blanking clearance h = a × t, where a = 10% to 20%. For example, when the test sheet 1 is 2mm thick, a punch 31 with a diameter of 3mm can be selected. The inner diameter of the die 32 should satisfy the blanking clearance h = 10% × t, and the inner diameter of the die 32 should be 3.4mm. In addition, when performing the blanking and sheeting test on each specimen, the inner diameter of the die 32 corresponding to each specimen can be recorded first.

[0205] (2) Establishing the initial tensile strength analysis model and the initial crack elongation analysis model

[0206] right Figure 13 The maximum blanking force, thickness of the sample and tensile strength of the eight samples are fitted, with the maximum blanking force and thickness of the sample as independent variables and tensile strength as dependent variable, and then the following can be obtained: Figure 14 The curve shown in Figure 1 realizes the establishment of the initial tensile strength analysis model, where Figure 14 The horizontal axis is the maximum blanking force divided by the thickness of the sample, and the vertical axis is the tensile strength value; Figure 13 The average value of the fracture zone of the eight samples, the thickness of the sample and the fracture elongation are fitted. The average value of the fracture zone and the thickness of the sample are independent variables, and the fracture elongation is the dependent variable, and then the following can be obtained: Figure 15 The curve shown in Figure 1 is used to establish the initial fracture elongation analysis model, where Figure 15 The horizontal axis is the average value of the fracture zone divided by the thickness of the sample, and the vertical axis is the reciprocal of the elongation at fracture.

[0207] (3) Verification model

[0208] A verification plate was selected, which was a heat-treatment-free die-cast aluminum plate with a thickness of 3.0 mm. A standard tensile test and a blanking test were performed on the verification plate. The maximum blanking force obtained in the blanking test was introduced into the tensile strength analysis model, and the calculated data was compared with the tensile strength obtained in the standard tensile test. If it was within the allowable error range, it means that the initial tensile strength analysis model is feasible, that is, the initial tensile strength analysis model can be used as the target tensile strength analysis model. The fracture band value obtained in the blanking test was introduced into the fracture elongation analysis model, and the calculated data was compared with the fracture elongation obtained in the standard tensile test. If it was within the allowable error range, it means that the initial fracture elongation analysis model is feasible, that is, the initial fracture elongation analysis model can be used as the target fracture elongation analysis model.

[0209] See Figure 16 , showing that the tensile strength of the experimental plate calculated using the initial tensile strength analysis model is 262.46 MPa, while the tensile strength obtained through the standard tensile test is 270 MPa. Here, |262.46 - 270| / 262.46 = 0.029 < 10%, indicating that the initial tensile strength analysis model is feasible and can be used as the target tensile strength analysis model.

[0210] See Figure 16 , showing that the fracture elongation of the experimental plate calculated using the initial fracture elongation analysis model is 9.73%, while the fracture elongation obtained through the standard tensile test is 10.25%. Here, |9.73 - 10.25| / 9.73 = 0.053 < 10%, indicating that the initial fracture elongation analysis model is feasible and can be used as the target fracture elongation analysis model.

[0211] (4) Application of mechanical analysis model

[0212] Test plate 1 size 80x200mm, see Figure 17 The test points are spaced 20 mm apart, with a total of 27 test points, where the test points refer to the locations of the punching and sheet taking experiments.

[0213] exist Figure 17In the figure, the horizontal numbers ①②③ indicate the number of columns, and the vertical numbers ①②③④⑤⑥⑦⑧⑨ indicate the number of rows. By performing blanking experiments on 27 test points of test plate 1, the maximum blanking force and the average fracture zone values ​​at each of the 27 test points were obtained. Substituting the 27 maximum blanking force values ​​into the target tensile strength analysis model yields 27 tensile strength values, and substituting the 27 average fracture zone values ​​into the target elongation at fracture analysis model yields 27 elongations at fracture. See the figure for a schematic diagram of the 27 tensile strength values ​​and the 27 elongation at fracture values.

[0214] for Figure 19 , the tensile strength value in the Nth row and nth column in the figure corresponds to the test point in the Nth row and nth column in the figure, Figure 18 The elongation at break in row N, column N corresponds to the test point in row N, column N in the figure, for example, Figure 17 The test point in row 2 and column 3 corresponds to Figure 19 The tensile strength value in the second row and third column is 262.9208 MPa; Figure 17 The test point in row 2 and column 3 corresponds to Figure 18 The elongation at break value in the 2nd row and 3rd column is 7.7799115%.

[0215] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for determining mechanical properties, characterized in that: include: Acquiring data collected during a blanking operation on a test plate, the data at least including: Maximum blanking force, and / or characteristic data of fragments or punched holes obtained by performing the blanking operation on the test sheet; The data are input into a target mechanical property analysis model to obtain the tensile strength and / or elongation at break of the test plate.

2. The method for determining mechanical properties according to claim 1, wherein: The target mechanical property analysis model includes a target tensile strength analysis model and / or a target elongation at break analysis model, wherein: at least the maximum blanking force is an independent variable of the target tensile strength analysis model, and the tensile strength is a dependent variable of the target tensile strength analysis model; The characteristic data includes at least one of a rounded corner band, a bright band, a fracture band and a burr, wherein: at least one of the rounded corner band, the bright band, the fracture band and the burr is an independent variable of the target fracture elongation analysis model, and the fracture elongation is a dependent variable of the target fracture elongation analysis model.

3. The method for determining mechanical properties according to claim 1, wherein: The method further comprises: Acquiring test data of a plurality of different specimens, wherein the test data of any of the specimens includes tensile data of the specimen collected during a standard tensile test and blanking data of the specimen collected during a blanking test, wherein the tensile data includes tensile strength and / or elongation at break, and the blanking data includes at least one of maximum blanking force, fillet band, bright band, fracture band, and burr; Determining the relationship between the independent variable and the dependent variable of the same sample based on the test data of the multiple different samples, wherein the dependent variable is the tensile data of the sample and the independent variable is the blanking data of the sample; The target mechanical property analysis model is obtained by fitting the relationship between the independent variables and the dependent variables of a plurality of different samples.

4. The method for determining mechanical properties according to claim 3, wherein: The method comprises: In the same sample, the obtained tensile data of the sample is used as the dependent variable, and the obtained blanking data of the sample is used as the independent variable. The target mechanical property analysis model is obtained by fitting the relationship between the independent variable and the dependent variable of multiple different samples, including: In the same sample, the obtained tensile data of the sample is used as a dependent variable, and the obtained blanking data of the sample is used as an independent variable; an initial mechanical property analysis model is obtained by fitting the relationship between the independent variable and the dependent variable of multiple different samples; The initial mechanical property analysis model is analyzed and verified to obtain the target mechanical property analysis model.

5. The method for determining mechanical properties according to any one of claims 1 to 4, characterized in that: A punching device is used to perform a punching operation on the test plate, wherein the punching device includes a punch rod, and the relationship between the diameter d of the punch rod and the thickness t of the test plate is: d≤1.5×t; and / or the punching gap h=a×t, wherein a=10%~20%.

6. The method for determining mechanical properties according to any one of claims 1 to 4, characterized in that: The collection of characteristic data of the fragments includes the following: Using an image acquisition device to acquire a picture of the circumferential side surface of the fragment, wherein the image acquisition device is used to generate an expanded view of the entire circumferential side surface of the fragment; Using an image measuring device to measure two or more bright band values ​​and two or more broken band values; The bright band value of the fragment is obtained by averaging the values ​​of the bright bands, and the broken band value of the fragment is obtained by averaging the values ​​of the broken bands.

7. A force measurement system, characterized in that: include: Analytical equipment for carrying out the method for determining mechanical properties according to any one of claims 1 to 6.

8. The force measuring system according to claim 7, wherein: The force measurement system further comprises: The punching and collection device is used for punching a test plate and collecting data of at least one of the maximum punching force, rounded corner band, bright band, broken band and burr.

9. The force measuring system according to claim 8, wherein: The punching and acquisition equipment includes a punching device and an image acquisition unit; The punching device includes a press, a punch rod, a die and a die base, wherein the die is supported on the press by the die base, the punch rod is connected to the press and is arranged above the die, and a matching hole for the punch rod to be inserted is provided on the die; An installation cavity is formed in the die base, the installation cavity is communicated with the matching hole on the die, and the image acquisition part is arranged in the installation cavity.

10. The force measuring system according to claim 9, wherein: The image acquisition part includes a supporting shell, a supporting tray and a camera. The supporting tray and the camera are supported on the supporting shell. There are multiple cameras and they are arranged in sequence along the circumferential direction of the supporting tray. The supporting tray is used to receive the debris falling from the matching hole.

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