Prediction method of blanking boundary quality of steel plate under different blanking gaps

Abstract

The present invention discloses a method for predicting the quality of the blanking boundary of a steel plate under different blanking gaps, comprising the following steps: S1, performing blanking using a blanking die to obtain multiple groups of test specimens having blanking gaps at different blanking gap ratios; S2, performing a tensile test on the test specimens using a tensile testing machine; and S3, predicting the quality of the blanking boundary of the steel plate based on the maximum tensile force applied when the test specimens break. The method for predicting the quality of the blanking boundary of a steel plate under different blanking gaps of the present invention can shorten the cycle for predicting the quality of the blanking boundary of a steel plate under different blanking gaps and improve the accuracy of prediction. This method enables steel manufacturers to more accurately evaluate the hole expansion performance of a material and is of great guiding significance for optimizing the blanking forming process of parts and stabilizing production.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel plate blanking quality detection, and in particular relates to a method for predicting the quality of steel plate blanking boundaries under different blanking gaps. Background Art

[0002] The blanking quality of steel plates directly affects the stability of subsequent forming, especially for high-strength steel. As the quality of the blanking boundary decreases, the probability of boundary cracking in subsequent forming will also increase sharply. With the higher requirements for lightweighting of new energy vehicles, the proportion of high-strength steel applications is increasing, and the problem of high-strength steel boundary cracking has received people's attention. Among them, the blanking gap is an important factor affecting the quality of the blanking boundary, and a lot of research has been carried out in the industry. For example, the patent documents with authorization announcement numbers CN201371188Y, CN205128715U and CN202239177U all provide a blanking die with an adjustable blanking gap. The gap adjustment method only makes an appropriate fuzzy increase or decrease relative to the previous gap, and the specific gap value cannot be determined. For example, in the patent documents with publication numbers CN110125237A and CN114509554A, the punch and die are replaced to achieve blanking with different gaps. Although the gap value can be determined, the mold has many parts, and the replacement is frequent and complicated, and the accuracy cannot be guaranteed. Among them, the quality judgment provided in the patent document with publication number CN114509554A is only a subjective visual judgment of the quality of the boundary, and no quantitative judgment result is given for the blanking quality.

[0003] However, during the process design phase of high-strength steel parts, when simulating the forming process, it is necessary to set the corresponding maximum shear stress parameter based on the blanking quality of the boundary to accurately predict the cracking of the subsequent forming results. Currently, there is no reasonable method to quantitatively evaluate the boundary quality of various materials at different blanking gaps. Therefore, during the process design phase, it is impossible to accurately predict the risk of boundary cracking in the subsequent forming process. This leads to uneven cracking in later production, resulting in unstable stamping production, reduced part production efficiency, and increased part cost. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for predicting the quality of the blanking boundary of a steel plate at different blanking gaps, the purpose of which is to shorten the period of predicting the quality of the blanking boundary of a steel plate at different blanking gaps and improve the prediction accuracy.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a method for predicting the quality of the blanking boundary of a steel plate under different blanking gaps, comprising the steps of:

[0006] S1. Blanking is performed using a blanking die to obtain multiple sets of blanking gap specimens with different blanking gap ratios;

[0007] S2. Perform a tensile test on the sample using a tensile testing machine;

[0008] S3. Predict the quality of the steel plate blanking boundary based on the maximum tensile force the sample is subjected to when it breaks.

[0009] In step S1, the punching die includes independent male and female punching combination modules, and multiple groups of independent male and female punching combination modules are provided. The punching gaps of the independent male and female punching combination modules in each group are different.

[0010] In the step S1, 16 groups of independent male and female die punching combination modules are provided.

[0011] The step S1 comprises:

[0012] S101. Provide an initial sample;

[0013] S102, processing a certain number of initial specimens to form notches on the initial specimens to produce group 0 notched specimens;

[0014] S103, performing blanking processing on a certain number of initial specimens to produce a first set of notched specimens;

[0015] S104. Repeat step S103 four times to produce the second group of notched specimens, the third group of notched specimens, the fourth group of notched specimens, and the fifth group of notched specimens respectively.

[0016] In the step S101, the number of initial samples provided is 24; in the step S102, the 4 initial samples are subjected to wire cutting; and in the step S103, the 4 initial samples are subjected to punching.

[0017] In step S1, the blanking die is provided with 16 groups of independent convex-concave die blanking combination modules with different blanking gaps. When 5 groups of independent convex-concave die blanking combination modules are selected, the blanking gaps of the 5 groups of independent convex-concave die blanking combination modules are evenly distributed between 0-20%*T, where T is the thickness of the initial sample.

[0018] The thickness of the initial sample is between 0.8 mm and 2.0 mm.

[0019] The step S2 comprises:

[0020] S201, using a tensile testing machine to stretch the notched specimens of group 0, respectively recording the maximum tensile force applied to each specimen of group 0 when the notched specimens are broken, and calculating the average value Fm0 of the maximum tensile force applied to the notched specimens of group 0 when the notched specimens are broken;

[0021] S202. Repeat step S201 five times to calculate the average values ​​of the maximum tensile forces Fm1, Fm2, Fm3, Fm4, and Fm5 of the maximum tensile forces applied to the first, second, third, fourth, and fifth groups of notched specimens when they are fractured, respectively.

[0022] The step S3 comprises:

[0023] S301, take the wire cutting notch boundary quality as the benchmark, according to the formula Sn=(Fm0-Fm n ) / Fm0, calculate the boundary quality damage ratio S under other blanking gaps, Sn is the boundary quality damage ratio under the corresponding gap of the nth group of notched specimens, Fm n is the average value of the maximum tensile force when the nth group of notched specimens are broken calculated in step S202; take Fm n =Fm1, calculate the boundary quality damage ratio S1 under the blanking gap corresponding to the first group of notch specimens; take Fm n =Fm2, calculate the boundary quality damage ratio S2 under the blanking gap corresponding to the second group of notch specimens; take Fm n =Fm3, calculate the boundary quality damage ratio S3 under the blanking gap corresponding to the third group of notch specimens; take Fm n =Fm4, calculate the boundary quality damage ratio S4 under the blanking gap corresponding to the fourth group of notch specimens; take Fm n =Fm5, calculate the boundary mass damage ratio S5 under the blanking gap corresponding to the 5th group of notched specimens;

[0024] S302 , plotting a boundary quality damage curve with the blanking gap ratio as the X-axis and the boundary quality damage ratio as the Y-axis.

[0025] The method for predicting the boundary quality of steel plate blanking under different blanking gaps of the present invention can shorten the cycle of predicting the boundary blanking quality of steel plates under different gaps and improve the prediction accuracy; this method can enable steel production enterprises to more accurately evaluate the hole expansion performance of materials, which is of great guiding significance for optimizing the blanking forming process of parts and stabilizing production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] This manual includes the following drawings, which show the following contents:

[0027] Figure 1 This is a flow chart of a method for predicting the quality of blanking boundaries of steel plates under different blanking gaps of the present invention;

[0028] Figure 2 is a schematic diagram of the structure of the initial sample;

[0029] Figure 3 It is a structural diagram of the notched specimen;

[0030] Figure 4 It is a top view of the lower die of the blanking die;

[0031] The following are marked in the figure: 1. lower die body; 2. guide assembly; 3. independent male and female die blanking combination module; 4. specimen. DETAILED DESCRIPTION

[0032] The following is a further detailed description of the specific implementation methods of the present invention through the description of the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and to facilitate their implementation.

[0033] like Figure 1 As shown, the present invention provides a method for predicting the quality of the blanking boundary of a steel plate under different blanking gaps, comprising the steps of:

[0034] S1. Blanking is performed using a blanking die to obtain multiple sets of blanking gap specimens with different blanking gap ratios;

[0035] S2. Perform a tensile test on the sample using a tensile testing machine;

[0036] S3. Predict the quality of the steel plate blanking boundary based on the maximum tensile force the sample is subjected to when it breaks.

[0037] Specifically, in the above step S1, the blanking die includes independent male and female die blanking combination modules, and the independent male and female die blanking combination modules are provided in multiple groups, and the blanking gaps of the independent male and female die blanking combination modules in each group are different.

[0038] In this embodiment, in the above step S1, Figure 4 As shown, the lower die part of the punching die includes a lower die body 1, a guide assembly 2 and an independent convex-concave punching combination module 3. The independent convex-concave punching combination module 3 is provided with 16 groups. The punching die is provided with 16 different punching gaps. These 16 gaps are set according to the thickness range of the material to be studied, which can meet the requirements of all material thicknesses. 5 gaps can be selected from the 16 gap combinations and are relatively evenly distributed between 0-20% of the thickness.

[0039] The above step S1 includes:

[0040] S101. Provide an initial sample;

[0041] S102, processing a certain number of initial specimens to form notches on the initial specimens to produce group 0 notched specimens;

[0042] S103, performing blanking processing on a certain number of initial specimens to produce a first set of notched specimens;

[0043] S104. Repeat step S103 four times to produce the second group of notched specimens, the third group of notched specimens, the fourth group of notched specimens, and the fifth group of notched specimens respectively.

[0044] In the above step S101, the initial samples are made by wire cutting, and the number of the initial samples is 24. Figure 2 As shown, the initial specimen is a steel plate with a rectangular sheet structure, L is the length of the initial specimen, and W is the width of the initial specimen.

[0045] In the above step S102, the four initial samples are subjected to wire cutting to form notch shapes on the initial samples, thereby producing the zeroth group of notch samples.

[0046] In the above step S103, four initial samples are punched out. According to the thickness T of the initial sample, one set of independent male and female die combination modules is selected in the punching die, and the initial sample is placed on the punching die for punching to produce the first set of notched samples.

[0047] Similarly, in the above step S104, four initial samples are punched out each time, and the punching process is repeated four times. Four notch samples with the same punching gap are punched out at each position of the punching die, generating the second group of notch samples, the third group of notch samples, the fourth group of notch samples and the fifth group of notch samples respectively.

[0048] In the above step S1, 16 groups of independent convex-concave die blanking combination modules with different blanking gaps are provided in the above blanking die. When 5 groups of independent convex-concave die blanking combination modules are selected, the blanking gaps of the 5 groups of independent convex-concave die blanking combination modules are evenly distributed between 0-20%*T, where T is the thickness of the initial sample.

[0049] In this embodiment, the initial sample is made of high-strength steel material for automotive parts, and the thickness of the initial sample is between 0.8 mm and 2.0 mm. Based on this thickness range, 16 gaps of the blanking die are designed as shown in Table 1 below.

[0050]

[0051] In step S103, when selecting the five independent male and female die modules, in principle, the corresponding blanking gaps are evenly distributed between 0% and 20%*T. In this example, the initial sample thickness is 1.2 mm. Based on this thickness, the five blanking modules numbered 1, 3, 7, 10, and 12 in the table above are selected for blanking. The corresponding gap ratios are calculated as shown in Table 2.

[0052]

[0053] The above step S2 includes:

[0054] S201, using a tensile testing machine to stretch the notched specimens of group 0, respectively recording the maximum tensile force applied to each specimen of group 0 when the notched specimens are broken, and calculating the average value Fm0 of the maximum tensile force applied to the notched specimens of group 0 when the notched specimens are broken;

[0055] S202. Repeat step S201 five times to calculate the average values ​​of the maximum tensile forces Fm1, Fm2, Fm3, Fm4, and Fm5 of the maximum tensile forces applied to the first, second, third, fourth, and fifth groups of notched specimens when they are fractured, respectively.

[0056] The above step S3 includes:

[0057] S301, take the wire cutting notch boundary quality as the benchmark, according to the formula Sn=(Fm0-Fm n ) / Fm0, calculate the boundary quality damage ratio S under other blanking gaps, Sn is the boundary quality damage ratio under the corresponding gap of the nth group of notched specimens, Fm n is the average value of the maximum tensile force when the nth group of notched specimens are broken calculated in step S202; take Fm n =Fm1, calculate the boundary quality damage ratio S1 under the blanking gap corresponding to the first group of notch specimens; take Fm n =Fm2, calculate the boundary quality damage ratio S2 under the blanking gap corresponding to the second group of notch specimens; take Fm n =Fm3, calculate the boundary quality damage ratio S3 under the blanking gap corresponding to the third group of notch specimens; take Fm n =Fm4, calculate the boundary quality damage ratio S4 under the blanking gap corresponding to the fourth group of notch specimens; take Fm n =Fm5, calculate the boundary mass damage ratio S5 under the blanking gap corresponding to the 5th group of notched specimens;

[0058] S302 , plotting a boundary quality damage curve with the blanking gap ratio as the X-axis and the boundary quality damage ratio as the Y-axis.

[0059] In step S301, Sn quantitatively evaluates the damage ratio of the edge quality at a specific blanking gap relative to the wire cutting process. This can serve as effective reference data for blanking edge quality parameter input during the part process design phase, improving the accuracy of subsequent forming crack prediction.

[0060] In the above step S302, the gap corresponding to the minimum boundary quality damage is found according to the curve graph. This gap can be used as the optimal value of the blanking gap to determine during process design, thereby improving the blanking quality of the actual mold.

[0061] The above-mentioned method for predicting the quality of the steel plate blanking boundary has the following advantages:

[0062] (1) The blanking die used has a variety of independent blanking gap modules, which can punch out various blanking gap test gaps for research materials. It has a simple structure, convenient operation, reliability and stability, and improves the efficiency and accuracy of the test;

[0063] (2) This method can predict the mass loss ratio of the material boundary quality to the wire cutting boundary quality under a specific blanking gap, which can serve as an effective reference data for the parameter input of the blanking boundary quality in the part process design stage, improve the prediction accuracy of subsequent forming cracking, and effectively avoid the cracking of parts in the actual production process in the later stage, which leads to unstable production and failure to supply normally.

[0064] (3) This method can accurately find the blanking gap value with the best blanking quality for various thicknesses of research materials. This gap can be used as the optimal reference value for determining the blanking gap during process design, thereby improving the quality of actual die blanking parts and extending the service life of the die.

[0065] The present invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described method. Any non-substantial improvements made using the method concepts and technical solutions of the present invention, or any direct application of the above-described concepts and technical solutions to other situations without modification, fall within the scope of protection of the present invention.

Claims

1. A method for predicting the quality of blanking edges of steel plates under different blanking gaps, characterized in that: Including steps: S1. Blanking is performed using a blanking die to obtain multiple sets of blanking gap specimens with different blanking gap ratios; S2. Perform a tensile test on the sample using a tensile testing machine; S3. Predict the quality of the blanking edge of the steel plate based on the maximum tensile force applied to the specimen when it breaks; Wherein, the step S1 includes: S101. Provide an initial sample; S102, processing a certain number of initial specimens to form notches on the initial specimens to produce group 0 notched specimens; S103, performing blanking processing on a certain number of initial specimens to produce a first set of notched specimens; S104, repeat step S103 four times to produce the second group of notched specimens, the third group of notched specimens, the fourth group of notched specimens, and the fifth group of notched specimens respectively; The step S2 comprises: S201, using a tensile testing machine to stretch the notched specimens of group 0, respectively recording the maximum tensile force applied to each specimen of group 0 when the notched specimens are broken, and calculating the average value Fm0 of the maximum tensile force applied to the notched specimens of group 0 when the notched specimens are broken; S202, repeat step S201 five times, and calculate the average values ​​of the maximum tensile forces Fm1, Fm2, Fm3, Fm4, and Fm5 of the first, second, third, fourth, and fifth groups of notched specimens when they are fractured, respectively; The step S3 comprises: S301, take the wire cutting notch boundary quality as the benchmark, according to the formula Sn=(Fm0 - Fm n ) / Fm0, calculate the boundary quality damage ratio S under other blanking gaps, Sn is the boundary quality damage ratio under the corresponding gap of the nth group of notched specimens, Fm n is the average value of the maximum tensile force when the nth group of notched specimens are broken calculated in step S202; take Fm n =Fm1, calculate the boundary quality damage ratio S1 under the blanking gap corresponding to the first group of notch specimens; take Fm n =Fm2, calculate the boundary quality damage ratio S2 under the blanking gap corresponding to the second group of notch specimens; take Fm n =Fm3, calculate the boundary quality damage ratio S3 under the blanking gap corresponding to the third group of notch specimens; take Fm n =Fm4, calculate the boundary quality damage ratio S4 under the blanking gap corresponding to the fourth group of notch specimens; take Fm n =Fm5, calculate the boundary mass damage ratio S5 under the blanking gap corresponding to the 5th group of notched specimens; S302 , plotting a boundary quality damage curve with the blanking gap ratio as the X-axis and the boundary quality damage ratio as the Y-axis.

2. The method for predicting the quality of the blanking edge of a steel plate under different blanking gaps according to claim 1, characterized in that: In step S1, the punching die includes independent male and female punching combination modules, and multiple groups of independent male and female punching combination modules are provided. The punching gaps of the independent male and female punching combination modules in each group are different.

3. The method for predicting the quality of the blanking edge of a steel plate under different blanking gaps according to claim 2, characterized in that: In the step S1, 16 groups of independent male and female die punching combination modules are provided.

4. The method for predicting the quality of the blanking edge of a steel plate under different blanking gaps according to claim 1, characterized in that: In the step S101, the number of initial samples provided is 24; in the step S102, the 4 initial samples are subjected to wire cutting; and in the step S103, the 4 initial samples are subjected to punching.

5. The method for predicting the quality of steel plate blanking edges under different blanking gaps according to claim 1, characterized in that: In step S1, the blanking die is provided with 16 groups of independent convex-concave die blanking combination modules with different blanking gaps. When 5 groups of independent convex-concave die blanking combination modules are selected, the blanking gaps of the 5 groups of independent convex-concave die blanking combination modules are evenly distributed between 0-20%*T, where T is the thickness of the initial sample.

6. The method for predicting the quality of the blanking edge of a steel plate under different blanking gaps according to claim 5, characterized in that: The thickness of the initial sample is between 0.8 mm and 2.0 mm.

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