Research On Adaptive Control Technology Of Medium Frequency Resistance Spot Welding

The resistance spot welding process is widely used in industrial manufacturing due to its high efficiency,reliability,and aesthetic advantages.However,various complex welding conditions may occur during batch production,such as close welding distances,changes in the thickness of the welded parts,and foreign objects between workpieces,which can lead to a decrease in welding quality and an increase in the cost of post-weld quality inspection.Therefore,researching adaptive control technology for resistance spot welding under complex conditions is crucial to improving welding consistency.This paper proposes a new adaptive control strategy for spot welding on the basis of previous studies.The strategy realizes self-adaptation by adjusting welding current and welding time in real time during the welding process,including current adjustment strategy and time adjustment strategy.This paper proposes a new adaptive control strategy for resistance spot welding based on existing research.The strategy can dynamically adjust the welding current and time during the welding process.The strategy consists of two parts: current regulation strategy and time regulation strategy.The current regulation strategy is an improved combination of reference power control and constant current control.Reference power control is an adaptive method for spot welding that ensures the quality of welds by controlling the consistency of the welding power curve.The current regulation strategy proposed in this paper introduces a resistance prediction model based on reference power control and adds constant current control to cope with situations where welding time needs to be extended.To better coordinate the control of welding current with the current regulation strategy,a fuzzy PI current controller with parameter self-tuning is designed.The principle of the time regulation strategy is to set welding goals related to dynamic resistance characteristics instead of welding time as the criterion for determining the end of welding,enabling adaptive adjustment of welding time.Finally,the software and hardware of an intermediate frequency resistance spot welding machine are designed,and an experimental platform is built using the welding machine to verify the proposed adaptive welding strategy under common interference conditions.The results show that the proposed adaptive control strategy for resistance spot welding can obtain reliable welds with a fusion zone diameter not less than the reference welds under four typical interference conditions.Figure [59] Table [6] Reference [84]...