Study On Deposition Morphology And Digital Twin Simulation Of Deposition Process In Wire And Arc Additive Manufacturing

Wire and Arc Additive Manufacturing(WAAM)is a wire feed additive manufacturing technology that uses welding arc as a heat source and metal wire as a raw material.It has the advantages of high deposition rate,low cost,high density of components,and the ability to fabrication complex parts,so it is widely valued by industry and academia.Generally speaking,the process of WAAM can be described as CAD model building,slicing,deposition path planning and welding parameter setting of each layer,communication with robot,manufacturing metal components layer-by-layer from bottom to top.Among them,slicing and deposition path planning need the data of weld bead cross-section shape as support.Therefore,it is very important to obtain the shape data of weld bead under different welding parameters for the realization of automatic WAAM.At the same time,in order to realize the flexibility and timeliness of the customized production of WAAM,it is necessary to carry out the research on the full digital simulation platform of WAAM.In this paper,the influence of welding process parameters on the components size is studied as the starting point.Combined with the established equations of welding process parameters and forming size,the size and profile of the weld bead are predicted,and the digital twin model of the forming process of the weld bead is built in MATLAB.Firstly,an image analysis system based on image processing and non-linear fitting with preset mathematical function model is developed by using MATLAB,and the good accuracy of the system is verified by experiments;the influence of torch speed and wire-feed speed on the forming size of single-bead is emphatically explored,and the range of process parameters with good forming morphology is obtained,and the profile of the weld bead forming in this interval was divided into semi-elliptic function and cosine function models.Secondly,the quadratic regression equations between the welding process parameters(torch speed,wire feeding speed and welding voltage)and the single-bead forming size,the top-level contour size of multi-layer single-pass(layer melting width,total melting height,the height of the quarter layer melting width,the height of the top-level contour),the welding process parameters and the number of deposition layers are established.At the same time,it is found that the uppermost contour of the multi-layer single pass tends to be semi-elliptic.Then,based on the principle of area conservation,the parabolic function is used to model the contour of the remelting point in the multi-layer single pass stacking,and the dynamic simulation of the weld bead forming in the fully digital-driven multi-layer single pass stacking process is realized using MATLAB.To sum up,based on image processing and image automatic analysis system with preset mathematical function model,this paper can automatically obtain the profile and size information of weld bead,determinethe optimal mathematical model of weld bead profile under the corresponding welding process parameters;establish the mathematical relationship between process parameters and weld bead profile under four deposition modes,and the prediction of the size and shape of the weld bead is realized.Based on the concept of digital twin,the evolution of weld bead morphology in the process of digital accumulation is preliminarily constructed.