The Influencing Rule And Experimental Research Of Edge Effect In Laser Bending

As a no-mold and new flexible sheet metal forming method, Laser bending have many advantages such as high forming precision and easy control, so it has important application prospects in areas such as aerospace and microelectronics. But in laser forming process, sheets'non-expected deformations (called edge effect) come with the expected deformations, which influence the forming precision. Thus, the urgent is to balance the contradiction between the two phenomena. That is to reduce the undesired deformation, and ensure the expected distortion at the same time.Under the support of the project of natural science foundation, the paper discusses the present research status and development of laser bending and edge effects, analyses the modeling mechanism of laser bending of aluminum, establishes a three-dimensional model of laser bending, studies the effect of various processing parameters on edge effect with orthogonal experiments, and explores the similarity theory of the edge effect with different materials. The concrete research content is as follows: Firstly, the paper analysis molding mechanism of laser bending based on heat transfer and elastic-plastic mechanics theory, and establishes the three-dimensional symmetrical finite element model by using Ansys software. APDL programming language is adopted, and surface effect element surf152 is introduced to simulate the moving laser heat source and heat transfer model. The study shows that the reason why the edge effects happen is that there is residual stress in the sheets.This paper presented an experimental study on the edge effects of laser bending on aluminum alloy. With RBAV as the criterion of edge effects, the effects of laser power, beam diameter and scanning velocity on edge effects are discussed. The most significant effect factor on edge effect is beam diameter, and the laser power and beam diameter have the greatest interaction effects on edge effects. Through the Taguchi design method, the optimal processing parameters are obtained. A regression equation which can be used to predict edge effect is established by regression analysis.In order to reduce the number of experimental tests, the similarity theory is introduced to study the edge effects of laser bending with different materials. Based on dimensional analysis and equations derived analysis, the similarity rule of temperature and deformation field is got. Research shows that similarity theory does not apply to edge effect of different materials. Based on the strain energy, the similarity theory is improved, and based on model-based test new similarity rule is got. Finally, experimental verification of the 304 stainless steel and aluminum is done and the experimental results show that the improved similarity of different materials for predicting the edge effect of laser forming is helpful.Finally, the paper summarizes all the done work and views the study direction in future.