With the rapid development of computer technology, in addition to the widely used computer-aided design (CAD) software for stamping dies. Computer Aided Engineering (CAE) software, which can simulate the forming process of stamping parts in a virtual environment, has gradually been adopted by the industry. world's attention and use. In recent years, in response to the shorter product development cycle and faster mold development efficiency, how to use CAE software to reduce the number of trial molds and reduce the cost of mold development has become a topic of concern to the industry. However, the threshold for using CAE software is relatively high, and it is difficult for engineers in the traditional stamping industry to get started. In addition, it is not easy to compare the analysis results of CAE software with the actual test conditions, which limits the application of CAE software. It is expected that through the introduction of these functional modules, the technical capabilities and international competitiveness of the stamping industry can be enhanced.
Some metal stamping parts, such as automobile sheet metal, aerospace parts, etc., are difficult to ensure the rationality of process parameter selection by using traditional empirical methods for mold design due to their complex shape, large outer contour size, relatively thin material, and high surface quality requirements. With the development of computer technology, CAD/CAE technology plays an increasingly important role in mold design and becomes an important way to make up for the shortcomings of traditional design methods. At the same time, it improves the design efficiency, reduces the design cost, and shortens the mold development cycle. Use CAE software to simulate the sheet metal stamping forming process for spring back analysis, fatigue analysis, and wear analysis of the mold. And predict the cracks, wrinkling, thinning, scratches, and other conditions of the sheet metal during the forming process, which can provide useful reference information for the optimization of the design parameters of the sheet metal stamping forming die.
For the stamping forming application field, CAE software such as Autoform, Dynaform, LS-DYNA, and Pam-stamp are commonly used in the general industry to simulate the sheet metal stamping forming process. Generally, CAE software has many parameters that can be set to use appropriate parameter values for different application cases. Therefore, it is very important for users of CAE software to have a deep understanding of the meaning of the parameters of this CAE software for stamping analysis applications, and to set these parameters correctly. However, the parameters of this CAE software are numerous and difficult to understand. Therefore, for engineers in the traditional domestic stamping industry in Taiwan, the use of CAE software usually requires long learning and accumulation of experience. In addition, when stamping dies development engineers use CAE software to analyze the results, although the die design can be adjusted according to the results. However, due to the limitations of the software and hardware functions of the measuring instruments, it is not easy to compare and adjust the results of the actual stamped product and the design simulation during the actual mold test. For stamping products with complex shapes such as automotive sheet metal and aerospace parts, if there is a system that can integrate virtual and real results, the efficiency of mold development can be accelerated.
Stamping Digital Process Design Prediction Module:
To allow CAE software users to use the professional language in the stamping field, with a fast and easy operation interface, set the analysis parameter data. Such as mold size/material, material size/material, and punch motion curve, and quickly translate it into what is needed for CAE analysis. File and parameter formats. Metal Center has developed a stamping digital process design prediction module, hoping to reduce the threshold for mold developers to enter CAE operations through the use of the module and improve the efficiency and quality of mold development.
The Setting Principles of CAE Software for Stamping Analysis:
LS-DYNA is a general-purpose large-deformation explicit dynamic analysis program, which can simulate formability, wrinkling, spring back, tonnage prediction, drawing a bead, die design and modification, etc. in the application of sheet stamping analysis. The accuracy of its results has also been verified in numerous cases. Since the main application field of LS-DYNA in the initial stage of development is collision analysis, most of its preset parameters are set for collision analysis. If you want to use it for stamping analysis, you must change the corresponding parameter settings. For beginners, there are certain difficulties.
LS-DYNA can set BOUNDARY, CONTACT, CONTROL, DATABASE, ELEMENT, MAT, NODE, PART, SECTION, and other parameters according to the application case. After these parameters are set, they will be stored in the Keyword file, referred to as the K file for short. After the K file is completed, the LS-DYNA solver can be used to read the K file parameters to solve the finite element analysis. Therefore, whether the parameter settings in the K file are appropriate will affect the results of the finite element analysis. The following will explain the matters needing attention in the CAE software setting for the stamping application.
In the actual stamping process, the moving speed of the mold in some application cases is slow, but in the simulation process, to speed up the calculation, it is necessary to increase the moving speed of the mold. Considering the number of explicit timestep cycles per millimeter of die movement, 100 to 1000 steps per millimeter of movement are recommended for most analyses. The maximum speed of the mold is recommended to be within 2 m/s to 5 m/s, and the speed travel curve should be defined to start and end at zero speed. The shape of the die motion curve can be trapezoidal or sinusoidal, and if servo stamping motion is considered, the implicit analysis mode should be used instead. For the mold ELEMENT parameter setting, shell elements can be used to reduce the calculation amount of finite element analysis. Since triangular elements are unavoidable in the meshing process, it is sometimes problematic to use quadrilateral element formulas to calculate these triangular elements, so it is recommended to turn on the function of automatically processing triangular elements with triangular element formulas. The thickness change function of the shell element also needs to be activated, which is very important to improve the accuracy of the stamping analysis.
In the MAT parameter setting section, it is recommended to use material parameters that can set anisotropy in the plate section to improve the accuracy of the analysis. Generally, the material parameters of the plate also need to input information such as yield strength and strain hardening curve. For the material of the mold, most of the rigid body materials can be used, and only parameters such as the density of the mold material, Young’s coefficient, and Poisson’s ratio need to be input. For CONTACT parameter setting, LS-DYNA has FORMING-ONE-WAY specially designed for forming applications, most users can just use its default value. In the BOUNDARY parameter setting part, the upper and lower degrees of freedom of the upper mold or the stripper is usually opened, and the translation or rotation degrees of freedom of other mold components are prohibited. The movement mode of the upper mold or the stripper plate is mostly set through the curve of time versus position, especially for the application of servo stamping. For the PART parameter setting, for the forming analysis of some complex parts, since the curvature changes greatly in many places, the adaptive meshing function must be used to automatically refine the sheet mesh.