Research On Laser Shock Line Clinching Of Foil

Laser shock line clinching,which combines laser shock forming technology and line connection technology,is a new technology with great development potential.It employs the shock wave pressure induced by laser pulses to shock foils and and makes plasma shock wave move along the line direction.Finally foils forms interlocking structure and realizing the line clinching.Laser shock line clinching forming in the processing process will not produce waste,which is a green environmental technology;Forming structure has good sealing and corrosion resistance.Various parameters of the laser can be adjusted to adapt to various work conditions,so it greatly improving the process adaptability.Therefore,laser shock line clinching technology has a strong advantage in the field of precision forming.This technique will have great potentials in aerospace and precision machining.In this paper,the process of the laser shock line clinching for foil and soltted die,foil and foil,foil and opening solt was studied.The matching die for line clinching process was designed independently.The influence of various experimental parameters on the forming process was studied,such as the forming height of foil H,laser energy E,laser power density P,numbers of pulse N,total energy W etc.From simple to difficult,the forming processes of point undercut structure,line undercut structure,and line clinching process are studied.The forming process of the point undercut structure was analyzed,and the P-N,P-W process curve of point undercut structure were established.The deformation mechanism of the line undercut structure and the influence of overlapping ratio on the line undercut structure forming were studied.Thickness analysis of the section of the line undercut structure is carried out.Several failure modes of the line undercut structures are introduced.An E-H process window of line undercut structure was established.In order to verify the experimental results,the numerical simulation of the line undercut structure process is carried out.Laser shock line clinching research mainly includes clinching for foil and opening slot and clinching for foil and foil.The influence of overlapping ratio and laser energy on laser shock line clinching was explored.The stress and strain of the formed material were analyzed.The main work and conclusions are as follows:(1)The forming evolution mechanism of point undercut structure,line undercut structure and line clinching was studied by using self-designed laser shock line clinching die,laser,displacement table and other experimental devices.Black ink as absorption layer and quartz glass as confinement layer.(2)The copper foil as the research object,then the copper foil is clinching with the slotted die by laser shock.At this time,the forming structure of the copper foil is called the point undercut strucutre.The point undercut strucutre can be regarded as a forming unit of the line undercut structure studied.Through a lot of experiments,P-N and P-W process curves of the point undercut structure are established.The research shows that the minimum numbers of pulse needed to form the point undercut structure decreases with the increase of laser power density during the forming process of the point undercut structure.Through numerical simulation,it can be clearly seen that the main steps of the forming process of point undercut structure are free bending,constrained forming,point undercut structure forming and point undercut structure.The stress and strain of the point undercut structure are analyzed.(3)line undercut structure is a structure formed by line clinching foil with slotted die by moving laser beam along the line direction and shocking foil with laser-induced plasma shock wave.The structure formed by foil is called line undercut structure.The length L of the line undercut structure is much larger than the width W,and the forming process is equivalent to the point undercut structure expanding along with the movement direction of the laser beam.The influence of overlapping ratio on the forming process of line undercut structure is investigated.The plastic deformation at r/=0%is more inhomogeneous than that at η= 50%.Thickness analysis of the section of the undercut structure shows that the foil around the undercut and the foil around the slotted die edge have the greatest thickness thinning ratio.Three failure modes can be concluded:corner fracture,bottom fracture and asymmetry.Fracture is mainly caused by thinning of foil thickness.Through a large number of experiments,the E-H process window for line undercut structure forming is established.Finite element simulation was carried out to analyze the shape evolution and deformation mechanism of the line undercut structure during the forming process,and the experimental results were verified.(4)The line clinching between foil/foil and foil/opening slot was studied.The line clinching process of foil/foil and foil/opening slot was simulated by finite element simulation method,and the strain of the formed foils was analyzed.The effects of overlapping ratio and pulse energy on line clinching process of foil/foil were studied.The experiments of foil/foil and foil/opening slot were carried out by forming die,and foil/foil were line clinching together successfully.