Multi-steps Design Of Large Deformation Curved Parts Of Aluminum Alloy And Its Multi-point Forming Simulation Study

Sheet metal forming has a wide range of applications in aerospace,automotive and marine manufacturing.The forming of three-dimensional curved parts has been mainly relying on integral die stamping to complete.Along with the diversification of products and the production of small batches,the disadvantages of long design cycle,high manufacturing cost and poor versatility of monolithic tooling are becoming more and more obvious.Faced with this problem,multi-point forming has obvious advantages.Multi-point forming uses discrete thinking,using independent and height-adjustable punches instead of a monolithic die,and adjusting the height of the punches through computer system control to obtain a forming surface composed of punch envelopes.Compared to monolithic dies,the forming surface of multi-point forming equipment can be changed and can be applied to multiple parts,which can save a lot of time and economic costs,and multi-point forming technology has been used in many engineering fields.This paper compares the commonly used integral die stamping and multi-point forming methods for thin sheet forming,and analyzes the scope of application and the respective advantages of the two forming methods.Based on the plastic forming theory of metal materials and finite element theory,the finite element analysis model of multi-point forming of sheet materials is established,including the geometric model establishment,material model selection,boundary condition setting,cell type selection and mesh division,and the rebound calculation method and the modeling method of multi-pass multi-point forming are elaborated.The multi-stage forming process is usually used to reduce the forming difficulty and improve the forming accuracy when multi-point forming of large deformed curved parts is performed.In this paper,we take the large-deformation hyperbolic component as the research object and apply the multi-pass forming process to compensate for the severe springback and forming difficulties.Numerical simulations are performed for one,two,three and four multi-pass forming of the target part to compare the quality and accuracy of multi-pass multi-pass forming of the part under different forming paths and find the best forming path for the target part.The forming quality and springback pattern of the four-pass forming parts are analyzed in detail,and it is verified that the four-pass forming can effectively suppress wrinkling and springback and obtain hyperbolic curvature curved parts with high forming quality.The three paths are linear,exponential and logarithmic functions,which ared²y/dx²=0、d²y/dx²>0 and d²y/dx²<0,respectively.The quality and accuracy of the surface parts formed by the three paths were analyzed from five perspectives:stress distribution,forming effect,forming quality,rebound,and forming error.The results show that:the logarithmic path forming parts have the best forming quality,the most uniform stress distribution,the rebound is well controlled,the forming accuracy is high,and the engineering standard of the parts is met;the exponential path forming parts have the worst forming quality and the lowest accuracy.