Study On Laser Bending Of Multilayer Composite Sheet Metal

Multilayer composite metal plate is a new type of composite material,which has been widely applied for many advantages.Laser bending forming technology belongs to a flexible forming technology of energy accumulation.The process does not require die,no contact and no external force,so it is very suitable for small batch and diversified product forming.Taking copper nickel composite sheet as the research object,the laser bending process of multilayer composite sheet metal is studied in this dissertation.The main research contents and progress are as follows:(1)A single factor experiment on the main factors affecting the bending of laser is carried out with a pulsed laser.It is found that the laser pulse frequency,the pulse width,the peak voltage and the scanning speed have a maximum effect on the bending angle,and the diameter of the spot and the scanning path(the distance between the scan line according to the free end of the line)is to the bending angle.At the same time,there is a minimax effect,while the influence of scanning times on the bending angle is increasing and the increment is decreasing.(2)Through the study of the metallographic structure,interfacial properties and hardness of multilayer composite sheet metal sheet after laser action,it is found that the interface of the copper nickel composite sheet is approximately a straight line.The intermediate layer of about 2 um appears near the interface.After multiple scanning of the laser,the grain is refined and close to the bending zone.Material accumulation appears in the fabric.The mutual diffusion of two elements appeared in the line scanning of nickel to copper,and the metallurgical bonding of multilayer composite metal sheets was strengthened by laser action.By testing the microhardness of the bending zone of Cu Ni composite sheet,it is found that the microstructure of the bending zone is hardening,and the closer the bending direction is,the greater the microhardness is.(3)Based on the parameter experimental design,the process parameters affecting the laser bending of Cu Ni composite thin plate are screened,and 5 process parameters which have great influence on the bending angle in the laser bending process are selected,which are scanning speed,scanning times,peak voltage,scanning path(line distance free distance distance)and light spot diameter,respectively.The mathematical model of peak voltage,scanning speed,scanning times,scanning path,spot diameter and angle of bending was established by using the center compound experiment design,and the interactive influence rules of various process parameters were revealed.The bending angle increases gradually when the peak voltage and the number of scanning times increase.When the scanning speed increases,the bending angle increases first and then decreases.With the increase of the spot diameter and the scanning path(the distance of the scan line to the free end),the bending angle is reduced first and then increases;the scanning speed is increased.The degree of interaction and the number of scanning have the greatest influence on the bending angle.Finally,the process parameters are optimized through the satisfaction function,and the ideal parameter combination is obtained.(4)The three-dimensional thermal structure model of copper nickel composite sheet was established on the platform of finite element analysis.The temperature field,stress strain field and displacement field during the laser bending of multilayer composite sheet metal sheet were numerically simulated.The distribution of temperature field,stress strain field and displacement field were obtained,and the temperature and stress should be found.The change is a process of periodic oscillation,and the displacement of the free end has a linear relationship with the time.The reliability of the finite element model is verified by the comparison of the data of the experimental deformation angle and the simulated deformation angle.