| Laser shock clinching/welding composite connection forming is a cross application of laser shock forming technology and ordinary connection technology.It uses laser-induced plasma explosion to drive a certain plastic deformation of the plate/foil,and further forms the welded sample into a clinch-shaped embedding This type of structure connects two or more layers of materials together to achieve a clinched/welded composite connection.This technology has important application prospects in the fields of automobiles,aircraft and microelectronics.In this paper,the experimental research on the double-layer copper foil welding process and the laser impact clinching/welding process and laser impact welding/clinching process of the copper foil and the open-hole stainless steel plate were carried out.,Analyze the deformation characteristics of the material during the forming process and the changes in the microstructure.From the aspects of the microstructure characteristics,macroscopic appearance and plastic flow characteristics of the material,analyze the form of material damage,further explain the damage mechanism,and establish the laser impact clinching/welding technology And the process window of laser impact welding/clinching technology,and the mechanical properties test and nano-hardness test of laser impact clinching/welding composite connection samples were carried out.The main work and conclusions are as follows:(1)Using Nd:YAG solid laser and numerically controlled stage,using quartz glass as the constraining layer,black ink and black paint as the absorbing layer,using self-designed clinching and welding forming molds,building a laser impact clinching forming experiment system and laser impact welding forming experiment The system uses different power lasers to conduct experiments on the pure copper foil welding and the laser shock clinching/welding composite connection process of copper foil and open-hole stainless steel plate.(2)The influence of laser energy,experimental materials and forming height on the laser impact welding process was studied,and the mechanical properties of the samples were tested.The results show that:under the condition of a certain flight distance of plate 1,the laser energy increases,the laser The higher the success rate of impact welding,the better the welding quality;under certain conditions of laser energy,the welding quality will increase significantly at the appropriate flight distance of plate 1;if the distance is too large,welding will fail and plate 1 will break and fail;The welding mold provides convenience for positioning the laser impact position and provides rigid support for the welding process;the mechanical properties of the sample have a certain relationship with the laser energy size and the forming height;SEM scanning shows that the welding area can form a good connection;laser confocal test It shows that the height of the bulge in the center of the welding sample is positively correlated with the laser impact energy;the nano-indentation test shows that the hardness of the material at the weld is slightly higher than the hardness of the material itself,and the material strength is improved to a certain extent.(3)The influence of process factors such as laser energy and forming height on laser clinching after laser welding and clinching process after laser shock welding were studied,and the mechanical properties of the samples were tested.The results show that:under a certain condition of the forming cavity height,with the higher laser energy,the better the quality of the clinched clinch after laser shock welding.The area of the welding area welded after laser shock clinching has increased;under certain conditions of laser energy,the quality of clinching after welding has increased significantly at the appropriate forming cavity height,The height is too small and there is not enough space for forming;the mechanical properties of the laser shock clinching/welding composite connection specimen have a certain relationship with the size of the laser energy and the forming height;SEM scanning shows that the welding area can form a good connection;nano-indentation test shows that The hardness of the material at the weld is slightly higher than the hardness of the material itself,and the strength of the material is improved to a certain extent.(4)The main reason for the destruction of the material during the laser shock clinching/welding composite connection forming is that the laser ablation caused by the material directly receiving laser shock after the absorption layer is consumed,and the second is that the material is thinned and stressed when plastic deformation occurs.Damage;there are two main types of damage caused by plastic deformation,the material damage at the upper edge of the opening of the stainless steel backing plate and the bottom damage of the clinch,of which the bottom damage of the clinch has the material damage at the undercut structure and the bottom center material.;After laser impact welding,the clinched specimens will also show incomplete clinching.(5)Fill in the parameters of the laser shock forming process table according to the experimental results,and determine the main parameters related to the laser shock clinching/welding composite connection by controlling the variables of laser energy and forming height.Parameter conditions for welding composite connections.(6)The mechanical performance test of the laser impact clinching/welding composite connection sample includes the shear test and the peeling test.The sample obtained by the laser impact clinching/welding composite connection technology has better shear resistance,and the maximum tensile force value is generally higher than pure clinched and pure welded samples;but the clinched structure has poor peel resistance.The maximum peel force of the laser impact clinched/welded composite connection sample is less than the pure welded sample.The material is thinned and the stress concentration will be to a certain extent when the clinched button is formed Affect the material strength. |
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