Numerical Simulation Research On Single-side Double Spot Welding Process For Stainless Steel Plate With Different Thickness

Resistance spot welding is a connection method which is stable welding quality and high production efficiency, easy to be mechanized and automotive, and it is applied in car, railway vehicle, electronics, household appliances and other manufacture fields widely. Resistance spot welding is a complex welding process, which involves the interactions of heat, electricity and force. At the same time, as a result of the invisibility of the nugget forming and the short of the welding time in the welding process, the numerical simulation study of spot welding process is imperative. Numerical simulation of spot welding is conducive to the further study of spot welding process and analyzing welding parameters on the welding process. Choosing the suitable parameters helps improve welding quality. At the present, the numerical simulation of spot welding mainly aims at the numerical simulation of the single spot welding, the numerical simulation of the single-side double spot welding is not usual. The production efficiency of the single-side double spot welding is higher than the single spot welding, and the application in the actual production of it will be more and more common.This article uses the general finite element software, establishing thermoelectric coupling model and thermodynamic coupling model. The 1mm+1.5mm of thickness combination of SUS304 stainless steel is numerically simulated by the use of spherical electrode and single pulse current in order to analyze the characteristics of temperature field and stress and strain distribution and research the influence of different welding process parameters on welding quality and the nugget forming process.This article analyzes finite element simulation of preloading in spot welding process, this analysis shows that the axial stress in electrode and work is compressive stress at the end of preloading. The maximum axial compressive stress appears in the center of the electrode and work interface area, the farther away from the center, the axial compressive stress is smaller. The maximum gradient of the axial compressive stress lies in the edge of the electrode and work interface area. The compressive plastic deformation happens in the electrode and work in the process of preloading, the maximum compressive plastic deformation of the electrode appears in the interior of the electrode-near the interface area of the electrode and work. The maximum compressive plastic deformation of the work appears in the contact area.The electrical heating process is simulated on the basis of the preloading simulation. According to the interface contact conditions when the preloading process is over, we kill the element which is not contacted on contact surface of the thermoelectric coupling model and simulate the thermoelectric coupling model. The thickness of 0.05 mm entity units are set up as the contact resistance in the interface. The temperature field at the end of the thermoelectric coupling simulation as the load is applied to the thermo force coupling model and then the thermo force coupling model is simulated. Until the end of the electric heating, the finite element simulation of the electric heating can be completed.After the simulation of electric heating process, the temperature distribution and the stress and strain distribution of the electric heating process can be concluded in order to analyze the formation of molten core. In order to study the influence of the different welding parameters on the forming process of welding molten core, the electric heating process by use of different welding parameters must be simulated. The simulation results show that the electrode pressure influences the spot welding penetration rate, molten core size is decreased by means of increasing electrode pressure. Welding current makes bigger influence on the forming process of molten core, the splash or the surface indentation may be produced if the welding current is too large. The influence of welding current time on the welding quality is similar to the influence of welding current on the welding quality.The numerical simulation research on single-side double spot welding for three layers stainless steel board with different thickness shows that the temperature field distribution in the process of spot welding. At the same time, we can study the effect of different welding parameters on the process of spot welding.