Abstract
Computer simulation technology has been widely used in the process of stamping forming, which can provide a powerful and reliable simulation platform for understanding and guiding the forming process. The core content of stamping forming process simulation technology includes the static analysis of stamping die and the dynamic analysis of stamping process. The essential technology includes the finite elements of structure, the material constitutive law, the contact analysis between dies and materials, the meshing of dies, the processing of finite elements, the integration of analysis modules, the analysis of dynamics, the simulation of human machine interface, and so on. This paper analyses the application of these core contents and essential technologies in the simulation of stamping forming process.
Introduction
Stamping, also known as punching or pressing, is the process of cutting or forming a workpiece into a predetermined shape using a press. It is one of the oldest forming processes, and is still widely used in auto parts, kitchenware, electronics and other industries. To meet the needs of mass production, stamping parts come with a high degree of accuracy and homogeneity.
The stamping forming process is very complicated, which greatly affects the machining accuracy, economy and efficiency of the parts. With the development of computer simulation technology, the technology of numerical simulation and optimization of stamping forming process has achieved rapid development. Through establishing a precise three-dimensional simulation model, it can quickly and reliably simulate the stamping process, predict various parameters and process characteristics, optimize the design and die shape of stamping parts, and provide technical support for optimizing process parameters.
Core content of stamping forming process simulation technology
The core application of stamping process simulation technology includes static analysis of stamping die and dynamic analysis of stamping process.
Static analysis of die
Static die analysis is used to calculate the structural strength of the die, as well as the deformation and wear of the die during the stamping process. The static die analysis is divided into two categories: time and frequency domain.
Time domain analysis involves reducing the linear static model and dynamic model of the die cavity discrete numerical analysis, and providing the purpose of the analysis is to obtain the internal force, stress state, displacement and temporary position of the selected important points on the die.
Frequency domain analysis is also called modal analysis. It is used to analyze the resonance frequency of the die during stamping process, to study the deformation of the die under different frequencies, and to prevent the structural failure caused by vibration or shock.
Dynamic analysis of stamping process
In the dynamic analysis of punch process, the dynamic model of punch system needs to be established. Based on the dynamic model, the contact relation between sheet and die can be calculated in linear, nonlinear, two-dimensional and three-dimensional way. It can also print the real-time process variables such as the size and shape of the processed parts, the temperature and strain of the forming materials, and the deformation of the forming tools. The dynamic stamping process analysis can provide powerful method for predicting the metal flow, material rupture phenomenon and other issues, thus providing strong theoretical support for the optimization of process parameters.
Essential technology
1. Finite elements of structure
The finite element of structure is used to simulate the real internal structure of the die. The finite elements are divided into four categories: Element Modeling, Material Modeling, Deformation Modeling and Contact Modeling. Element modeling includes the definition of nodes, element types and element properties. Material Modeling is to define the material type, properties and yield characteristics. Deformation modeling is to define the deformed final shape of each element, and contact modeling is to define the contact pairs of each element.
2. Material constitutive law
Material constitutive law is the basic theory of analysis of stamping process. It is used to describe the relationship between mechanical strength and plastic flow of materials. Plastic flow is the main material property which affects the stamping process. There are many kinds of material constitutive law, such as von Mises yield criterion, Mohr Coulomb yield criterion, Johnson Cook yield criterion, etc.
3. Contact analysis
Contact analysis between dies and sheets is the key technology to simulate stamping medium. Common contact analysis models include penalty method and augmented Lagrangian method. In penalty method, tension control penalty coefficient is used to simulate the contact of the parts, while augmented Lagrangian method adds penalty coefficient to the contact force and adds it to the Lagrange equation.
4. Meshing of die
The meshing of die surface is the basis of finite element analysis. The more uniform the mesh of die surface, the better accuracy of the analysis. Common meshing methods include linear triangle mesh, radial mesh and parametric mesh.
5. Finite element processing
Finite element processing is a basic process among finite element analysis. It is to combine finite elements with finite element analysis software, and to configuration node and element properties to carry out finite element analysis.
6. Integration of analysis modules
The integration of analysis modules is the key step to realize the stamping simulation. It can be achieved through COM or TCP technologies.
7. Analysis of dynamics
The analysis of dynamics is an important means to study the stamping process. It is used to analyze the dynamic behavior of the system, such as the transient response of the structure, the vibration and impact of the system and the dynamic balance of the system.
8. Simulating human machine interface
Simulating HMI is the core technology of process optimization. Through simulating and optimizing the interface, it can provide an intuitive man-machine interaction environment for the operator, and optimize the process and save cost.
Conclusion
This paper analyses the application of computer simulation technology in stamping forming process in depth. The core content and essential technologies of stamping forming process simulation technology are introduced, including the static and dynamic analysis of stamping die, the finite element of structure, the material constitutive law, the contact analysis between die and sheet, the meshing of die, the processing of finite element, the integration of analysis modules, the analysis of dynamics and the simulation of human machine interface. With the development and application of these contents and technologies, the simulation and optimization of stamping forming process will surely get further development.
