Small-batch stamping part standardized die material design method

Abstract

The invention provides a small-batch stamping part standardized die material design method. According to the method, based on the BUCKINGHAM pi theorem, key physical quantities such as die material hardness, plate hardness, stamping force, plate thickness, tensile strength and fracture toughness are converted into dimensionless indexes, failure criteria such as abrasion, deformation and fracture are established, and a multi-target optimization model of cost and service life is constructed. On the premise that the constraint conditions of abrasion resistance, deformation resistance and fracture resistance are met, medium carbon steel or aluminum bronze is preferentially selected, and high-cost and high-hardness materials are prevented from being used. According to the method, the wear resistance coefficient is calibrated through experiments, the service life prediction is dynamically corrected, and the die cost and development period can be remarkably reduced on the premise of guaranteeing the quality of the stamping part.

Description

Technical Field

[0001] This invention relates to the field of stamping die design, and more specifically, to a method for designing standardized die materials for small-batch stamping parts. Background Technology

[0002] With the increasing demand for flexible production and customization in the automotive industry, the market demand for the development of small-batch models and their components is growing. Existing mass-production stamping die material standards can guarantee part quality, but they are costly and time-consuming, making them unsuitable for the development of small-batch stamped parts. How to reduce die material costs and shorten development cycles while ensuring part quality has become a crucial issue in the development of small-batch models. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a standardized die material design method for small-batch stamping parts. By establishing a dimensionless criterion and optimization model based on dimensional analysis, the die material can be scientifically selected, avoiding cost waste and performance redundancy caused by experience-based material selection, and improving the scientific and economical nature of die design.

[0004] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0005] A method for designing standardized die materials for small-batch stamping parts includes the following steps:

[0006] Step S1. Collect and define the physical parameters and their dimensions required for the design, including: mold material hardness H;

[0007] Material tensile strength σ b Material fracture toughness K IC Stamping force F; sheet thickness T; sheet hardness Hs; stamping perimeter P; target number of stamped parts N; critical wear resistance coefficient C1;

[0008] Step S2. Construct dimensionless criteria based on the above physical quantities to guide material selection and lifespan prediction, including:

[0009] (1) Wear-dominant term π1: ;

[0010] When the wear-dominant term π1 of the selected material is less than C1, it indicates that the wear of the mold is acceptable.

[0011] (2) Deformation resistance term π2: ;

[0012] When 0.1 ≤ π2 ≤ 0.3, it indicates that the cutting edge does not crush.

[0013] (3) Fracture resistance term π3: ;

[0014] When π3 > 0.5, it indicates that the mold is not prone to brittle fracture;

[0015] Step S3. For each candidate material satisfying the constraints π2≤0.2 and π3≥0.6, calculate its minimum cost value minCOST and maximum lifetime value Nmax using the following cost function and lifetime function, thereby selecting candidate materials that balance cost and performance, where:

[0016] The cost function is:

[0017] Among them, C 材料 C represents the unit price of the material. 加工 For mold processing costs, These are the weighting coefficients.

[0018] The lifetime function is: ;

[0019] Step S4. Calculate whether the deformation resistance, fracture resistance, and wear resistance of the candidate materials selected in Step 3 meet the following constraints to ensure that the model's output meets actual production requirements:

[0020] Deformation resistance conditions: Fracture resistance conditions: Wear resistance conditions: ;

[0021] Step S5. Experimental calibration and dynamic correction: The actual wear amount is measured through trial stamping experiments to correct the critical wear resistance coefficient C1; in batch production, after each batch of stamping is completed, the edge wear is detected and the life prediction is updated based on π1.

[0022] Optionally, provided that the constraints in step S4 are met, medium carbon steel or aluminum bronze may be preferred.

[0023] Optionally, C1 is obtained through reverse calibration using up to 500 trial punches.

[0024] Optionally, when π3 < 0.5, powder metallurgy high-speed steel inserts can be used as a material substitute.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The method provided by this invention can reduce mold development costs and shorten the mold manufacturing cycle while ensuring the quality of stamped parts. At the same time, it can achieve a moderate mold life and sufficient resistance to failure, avoiding early fracture or plastic deformation. Attached Figure Description

[0027] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0028] Figure 1 This is a flowchart illustrating the steps of the standardized die material design method for small-batch stamping parts described in the embodiments. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, all directional indications (such as up, down, left, right, front, back, bottom, etc.) in this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indication will also change accordingly. Furthermore, descriptions involving "first," "second," etc., in this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0032] This embodiment proposes a standardized die material design method for small-batch stamping parts. The overall goal of this method is to reduce die development costs and shorten the die-making cycle while ensuring the quality of stamping parts, and to achieve a suitable die life and sufficient failure resistance to avoid early fracture or plastic deformation. This method avoids the excessive use of high-cost, high-hardness materials (such as D2 steel and cemented carbide), and instead uses scientific modeling and criterion analysis to rationally select material hardness, strength, and toughness, thereby meeting the production needs of 500-2000 small-batch stamping parts. This method uses BUCKINGHAM's π theorem to transform different physical quantities into a dimensionless group and establishes a mathematical model for failure criteria, including the following steps:

[0033] Step 1: Collect and define the key physical parameters and dimensions required for the design, including:

[0034] Hardness H of mold material: represents the ability to resist localized plastic deformation, with dimensions in m / L. −1 T −2 ;

[0035] Material tensile strength σ b : Represents the ability of a material to withstand tensile stress, with dimensions in ml. −1 T −2 ;

[0036] Material fracture toughness K IC : Represents the ability to resist crack propagation, with dimensions ML −3 T −2 ;

[0037] Punching force F: represents the load during the punching process, with dimensions in MLT. −2 ;

[0038] Sheet thickness T: Represents the thickness of the sheet metal being stamped, with the dimension L;

[0039] Sheet hardness Hs: Represents the hardness of the sheet material, with dimensions in ml. −1 T −2 ;

[0040] Punching perimeter P: represents the perimeter of the part's shape, with the dimension L.

[0041] Target stamping quantity N: represents the number of parts that the mold needs to complete, dimensionless.

[0042] Critical wear resistance coefficient C1: A dimensionless critical value obtained through experimental calibration, used to determine whether wear is acceptable.

[0043] Step 2: Construct the dimensionless group

[0044] Using Buckingham's π theorem, physical quantities with different dimensions are combined into a dimensionless criterion to guide material selection and lifespan prediction, wherein:

[0045] (1) The wear-dominant term (π1) represents the normalization of cumulative wear relative to the die hardness and blanking dimensions, and is calculated using the following formula:

[0046]

[0047] When the wear-dominant term π1 < C1 for the selected material, it indicates that the wear of the mold is within an acceptable range.

[0048] (2) The deformation resistance term (π2) is calculated using the following formula:

[0049]

[0050] When 0.1 ≤ π2 ≤ 0.3, it indicates that the cutting edge does not crush.

[0051] (7) The fracture resistance term (π3) represents the ratio of toughness to strength and size effect, and is calculated using the following formula:

[0052]

[0053] When π3 > 0.5, it indicates that the mold is not prone to brittle fracture. When π3 < 0.5, powder metallurgy high-speed steel inserts can be used as a material substitute.

[0054] Step 3: Establish an optimization model

[0055] For each candidate material, calculate its cost (COST) and lifetime (L), and evaluate whether it meets the constraints. Among all materials that meet the constraints, select the material with the lowest cost and the required lifetime. With the objectives of minimizing cost and maximizing lifetime, construct the following optimization model:

[0056] Define the cost function:

[0057] Among them, C 材料 C represents the unit price of the material. 加工 For mold processing costs, These are the weighting coefficients.

[0058] Define the lifetime function: ;

[0059] Define the constraints: π2≤0.2, π3≥0.6.

[0060] By solving this optimization model, a material selection scheme that balances cost and performance can be obtained, and candidate materials can be selected.

[0061] Step 4: Material Selection and Calculation

[0062] Based on the dimensionless criterion and optimization model, calculate whether the deformation resistance, fracture resistance, and wear resistance of the candidate materials selected in step 3 meet the following constraints to ensure that the model output meets actual production requirements:

[0063] Deformation resistance:

[0064] Fracture resistance:

[0065] Abrasion resistance:

[0066] Provided that the constraints are met, medium carbon steel (such as S50C, 40Cr steel) or aluminum bronze should be given priority, and excessive use of high hardness steel should be avoided.

[0067] Step 5: Experimental Calibration and Dynamic Correction

[0068] The actual wear amount is measured through trial stamping experiments to correct the critical wear resistance coefficient C1. In batch production, after each batch of stamping is completed, the cutting edge wear is detected, and the life prediction is updated based on π1. This step is the "implementation guarantee" and "dynamic adaptation" link of the entire small-batch stamping die material design method. Its core function is to correct the errors of the theoretical model through feedback from actual production data, and to continuously optimize material selection and life prediction during the production process, ensuring that the method is transformed from "theoretically feasible" to "practically usable".

[0069] The specific embodiments of the present invention have been described above. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

Claims

1. A method for designing standardized die materials for small-batch stamping parts, characterized in that, Includes the following steps: Step S1. Collect and define the physical parameters and their dimensions required for the design, including: mold material hardness H; Material tensile strength σ b Material fracture toughness K IC Stamping force F; sheet thickness T; sheet hardness Hs; stamping perimeter P; target number of stamped parts N; critical wear resistance coefficient C1; Step S2. Construct dimensionless criteria based on the above physical quantities to guide material selection and lifespan prediction, including: (1) Wear-dominant term π1: ; When the wear-dominant term π1 of the selected material is less than C1, it indicates that the wear of the mold is acceptable. (2) Deformation resistance term π2: ; When 0.1 ≤ π2 ≤ 0.3, it indicates that the cutting edge does not crush. (3) Fracture resistance term π3: ; When π3 > 0.5, it indicates that the mold is not prone to brittle fracture; Step S3. For each candidate material satisfying the constraints π2≤0.2 and π3≥0.6, calculate its minimum cost value minCOST and maximum lifetime value Nmax using the following cost function and lifetime function, thereby selecting candidate materials that balance cost and performance, where: The cost function is: Among them, C 材料 C represents the unit price of the material. 加工 For mold processing costs, These are the weighting coefficients. The lifetime function is: ; Step S4. Calculate whether the deformation resistance, fracture resistance, and wear resistance of the candidate materials selected in Step 3 meet the following constraints to ensure that the model's output meets actual production requirements: Deformation resistance conditions: Fracture resistance conditions: Wear resistance conditions: ; Step S5. Experimental calibration and dynamic correction: The actual wear amount is measured through trial stamping experiments to correct the critical wear resistance coefficient C1; in batch production, after each batch of stamping is completed, the edge wear is detected and the life prediction is updated based on π1.

2. The method for designing standardized die materials for small-batch stamping parts according to claim 1, characterized in that, Provided that the constraints in step S4 are met, medium carbon steel or aluminum bronze are preferred.

3. The method for designing standardized die materials for small-batch stamping parts according to claim 1, characterized in that, The C1 is obtained through reverse calibration using up to 500 trial punches.

4. The method for designing standardized die materials for small-batch stamping parts according to claim 1, characterized in that, When π3 < 0.5, powder metallurgy high-speed steel inserts are used as material replacements.

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