Bypass Coupled Arc Additive Manufacturing MIMO Decoupling Controlby

Arc additive manufacturing has obvious advantages in stacking formed parts.However,the accumulation of heat and the variation of welding height and wire feeding speed in the stacking process have brought great troubles to the stacking process,and the collapse in the stacking process is also a very difficult problem.This paper focuses on the theoretical analysis and experimental exploration of the control of the welding height and wire feeding speed during the stacking process and the improvement of the collapse problem.Firstly,the bypass coupled arc welding system was established by using xPC Target as the environmental background;the relationship between voltage and current and welding height and wire feeding speed was measured by experiments.MIMO closed-loop control system is established to study the control model,method of bypass current and voltage during 3D welding rapid prototyping stacking.Combined with MATLAB/Simulink software for modeling and simulation,wire feeding speed and welding height are monitored in the welding process.Secondly,based on the MIMO closed-loop control system,automatic arc starting and extinguishing control is added.The change of the pulse signal is used to realize the control of arc starting and extinguishing in the welding process,and the problem of the edge collapse of the stacking layer during the additive coupling manufacturing process of the bypass is studied.The change of the pulse signal is used to realize the control of arc starting and extinguishing in the welding process,so as to study stacking layer edge collapse in the process of bypass coupled arc additive manufacturing.Then,by analyzing the coupling relationship between wire feeding speed and welding height in MIMO closed-loop control system and in automatic arc starting and extinguishing control system,the matching relationship between wire feeding speed and controllable quantity(welding current and voltage)is defined,and the model under full coupling condition is established;by modeling and simulation through MATLAB / Simulink software,the changes of welding current,voltage and wire feeding speed under decoupling control and the precision of stacking are studied.Finally,through the experiments of single-lane,cross,ten-story and multi-story stacking,the results show that the MIMO closed-loop control system can fully monitor and adjust the changes in welding height and wire feed speed in real time during thewelding process,so as to achieve real-time control of the welding height and wire feed speed in the three-dimensional welding process.The voltage,current and wire feed speed signals under the automatic start-quench control system are relatively stable,the layer-to-layer transition is smooth,the collapse problem and the forming accuracy of the stacking parts are significantly improved.In the decoupling control system,the weld line in the single pass is stable,uniform and smooth in appearance;in the process of cross stacking,the perfect transition of cross position is completed to form a good cross weld;in the process of multi-layer cyclic stacking,the automatic arc starting and extinguishing control of arc is not affected,the transition between layers more stable,the wire feeding speed more balanced,and the appearance of stacking samples is beautiful and smooth,without obvious collapse.