Research On Optimization Of Welding Parameters Based On Loads Of Spot Welds

Resistance spot welding is the most important link process in car-body manufacturing. On one hand, resistance spot weld is the guarantee to auto-body performance. Through the reasonable selection of welding parameters, high strength weld joint could be got and making the car-body with good rigidity, crash safety and high reliability. On the other hand, resistance sp ot welding is one of the most high energy consumption process in car-body manufacturing. In batch production, unreasonable selection of welding parameters which cause welding spatter or faulty welded joints needed to be welded again is tremendous energy wa ste during the production process. Not knowing well of the spot weld loads under comprehensive status and mechanical property of the joint of the specific overlapping relation, it leads to spot welds with high strength far beyond the loads the joint bear, which is of great waste in the view of energy consumption, while other spot welds are with insufficient strength and in the risk of failure. Environmental protection, energy saving and safety are the future of automotive makers. Therefore, it is of great necessity to control the energy consumption and its influence to environment in welding production while making sure the quality of spot welds. Current welding parameter selection method lack comprehensive consideration of spot weld mechanical property and loads of the joint, thus we can not make sure that whether the spot weld under the specific welding parameters could meet the demand of car-body performance, even less consideration of energy consumption during welding production. Exactly according to this kind of consideration, this paper launch the research of welding parameters optimization.Firstly, this paper thoroughly study the mechanism of resistance spot welding and numerical simulation theory, set up multi-coupled resistance spot welding model and then simulate the welding process. Through researching the relationship between spot weld diameter and it’s mechanical property, establish the relationship between welding parameters and mechanical property of spot weld, provide an important mathematical model for the next research.Secondly, car-body mechanics finite element simulation and critical technology to improve simulation accuracy are introduced, and the new concept spot weld work load is presented and defined, and accordingly analyze the force c ondition of spot weld, which provides important information for the identification of spot weld risk of failure and optimization of joint quantity and offers a reference for the welding parameter selection.What’s more, the deficiency of traditional spot w eld quality evaluation criteria is analyzed and new criteria considering loads of spot weld and welding energy consumption is proposed. With the combination of the research described above and the equilibrium thought applied widely in other engineering are a, set up the mathematical relationship of “spot weld loads-spot weld mechanical property-welding parameters”, and further establish “quality-energy consumption” balance model of spot weld, and accordingly proposed welding parameters optimization based on spot weld loads.At last, take the safety belt anchorage simplified structure as the research subject, optimized the quantity of the spot weld of the structure and welding parameters according to the new method presented above and verified with experiments. The result shows that the optimized welding parameters can not only meet the requirement of mechanical properties of spot welds, but also reduce welding energy consumption by 55%, which is of great benefit to automobile factory.