| The 7075 aluminum alloy containing Al-Zn-Mg-Cu has the advantages of good mechanical properties,high recoverability,high hardness,light weight and good corrosion resistance.It is an important application in many high-performance index materials at home and abroad.Raw materials,and are widely used in aerospace,defense military,rail vehicles and automotive industries.At present,the traditional fusion welding method used in the application of 7075 super-hard aluminum alloy structural parts still lacks a comprehensive system solution for the problems of cracks,pores,softening and unevenness of the weldment,and instability.The problem of uncontrollable welding defects has severely restricted the improvement of the application level of super-hard aluminum alloy.Therefore,based on the welding experimental data obtained by adjusting the welding process parameters for the 7075 super-hard aluminum alloy TIG welding process,this paper studies the microstructure performance prediction and welding process control theory of 7075 super-hard aluminum alloy welded joints,and establishes 7075 super-hard aluminum alloy.Weldability and microstructure of welded joints affect the law and optimize control methods.In this paper,the mechanical properties and microstructure analysis of the welded joints obtained by the ER5356 welding wire under the TIG welding process of the 7075 super-hard aluminum alloy are firstly determined to determine the process parameters suitable for the weldability of the super-hard aluminum alloy.Then,by studying the nonlinear correspondence between the parameters of the 7075 superhard aluminum alloy TIG welding process and the microstructure performance,a prediction model of the organizational performance was established.Finally,based on the relationship between welding process parameter control and final microstructure performance,a robust control method for welding process is established.The main research contents of this paper are:Research on the optimal data sample experimental method for the corresponding mechanism of process parameters and microstructure performance of AIG7075-T651 aluminum alloy TIG welding process.The ER5356 welding wire was used as the filler metal for orthogonal optimization welding test.The influence mechanism of welding parameters such as welding current and welding speed on the microstructure of joints formed by final welding was studied.The tensile fracture morphology and different areas of welded joints were analyzed.The characteristics of strengthening phase are precipitated by aging,and the optimal sample set of measurement parameters such as current,voltage,welding speed and its corresponding welding joint microstructure performance parameters are established.The nonlinear dynamics between the measurement data of the 7075 superhard aluminum alloy TIG welding process and its structural performance test data were studied.The nonlinear system of the 7075 superhard aluminum alloy TIG welding process was established and studied,and the welding process was measured.The data is based on the time series of the welding process.The stationarity test method,nonlinear test method,phase space reconstruction and deterministic test method for nonlinear time series of welding process are studied.A phase space reconstruction and deterministic test method for nonlinear time series of 7075 superhard aluminum alloy TIG welding process parameters was established.The parameter calculation methods such as time series embedding dimension,delay time and maximum Lyapunov exponent of TIG welding process are studied.The phase space of tissue performance and its evolution trajectory model determined by the change of process parameters of welding process are established.Based on this,the welding based on welding is established.A global prediction model for the organization performance of nonlinear time series of process.To study the effect of various process parameters and their changes on the parameters of the final welded joint microstructure during the whole process of 7075 superhard aluminum alloy TIG welding,based on the welding process parameters on the time scale of the microstructure performance and the various welding processes The complex interaction relationship between the parameters is established,and each process parameter and tissue performance parameter are used as nodes,and the interaction function between each node is the network model of the dynamic mechanism of the connection.The Jacobian matrix description model of the interaction between the 7075 superhard aluminum alloy TIG welding process parameter nodes and the binding force acting on the entire network output point is studied.The network output of the welding process system and the nodes in the network are described.The constraint equation establishes the system dynamics model of the whole welding process.The motion law and motion control model of the relative motion between the welding gun and the weldment under the specific welding process parameters are studied under the three-dimensional coordinate system formed between the welding torch and the weldment in the 7035 superhard aluminum alloy TIG welding process.In the TIG welding process of 7075 super-hard aluminum alloy,the dynamic control model of the welding gun inclination angle and forward speed in the welding process under the condition of the robustness of the control model within the range of mechanical,physical and chemical factors is established,and the welding is established.A global motion state robust estimation model for the process.The computational quantity optimization method of motion control algorithm based on Gauss-Newton(GN)method in real-time welding process control is studied.The improved Gauss-Newton welding torch global motion dynamic real-time robust control algorithm which can realize the fast dynamic calculation of welding gun motion state is established.The motion law and motion control model of the relative motion between the welding gun and the weldment under the specific welding process parameters are studied under the three-dimensional coordinate system formed between the welding torch and the weldment in the 7035 superhard aluminum alloy TIG welding process.In the TIG welding process of 7075 super-hard aluminum alloy,the dynamic control model of the welding gun inclination angle and forward speed in the welding process under the condition of the robustness of the control model within the range of mechanical,physical and chemical factors is established,and the welding is established.A global motion state robust estimation model for the process.The computational quantity optimization method of motion control algorithm based on Gauss-Newton(GN)method in real-time welding process control is studied.The improved Gauss-Newton welding torch global motion dynamic real-time robust control algorithm which can realize the fast dynamic calculation of welding gun motion state is established. |
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