Research On Robot Frition Stir Welding System And Technology

In recent years,there has been an increasing demand for aerospace high-strength aluminum alloy large-scale thin-walled and complex curved siding structure.The complex curved siding structure has large structural dimensions,thin and weak wall rigidity,different configurations of siding and welding flanges,and large changes in curvature.It is urgent to develop a flexible and intelligent robot friction stir welding system with high rigidity,high motion accuracy,and high accessibility,and breakthrough key technologies such as heavy-duty robot body,welding sensing and control,and mutual coupling of robots and positioners.Realize the high-quality and efficient welding of high-strength aluminum alloy complex thin-walled curved wall structure,promote the domesticization and intelligentization of China's robot system,and further promote the engineering application of domestic robots.The use of tandem robots as the carrier of friction stir welding has high flexibility and large working space,but the rigidity of tandem robots is weak.The stirring head will receive greater upsetting force,forward resistance and lateral force during the welding process,which makes the robot Deformation occurs and the stirring head deviates from the welding track.During the pressing process of the stirring needle,the welded plate and the stirring head contact,the upsetting force increases sharply,and the robot deforms;during the withdrawal process of the stirring needle,the upsetting force decreases rapidly,and the robot deforms from the force to the robot recovery.As a result,the robot has a greater vibration.Based on this,this paper proposes to carry out research on the robot friction stir welding system,and completes the following work:This paper firstly takes the robot as the research object,expounds the forward kinematics and inverse kinematics of the robot and the positioner,and proposes a robot deformation compensation model based on the speed coordinate system.Secondly,for the robot friction stir welding system,a special electric spindle force sensor system for robot friction stir welding is designed and constructed.The force sensor is used to compensate the gravity of the special electric spindle,and the force model of the stirring head during the welding process is obtained and analyzed.For the robot end compliance control strategy,a hybrid control strategy based on impedance control is proposed and applied to the robot friction stir welding system.Thirdly,according to the composition of the robot friction stir welding system,a robot friction stir welding workstation with robots,special electric spindles,retractable shafts,positioners,etc.as the main body is established,and a coupling and decoupling model of robots and positioners as the main body is proposed.,And analyze the process control of robot friction stir welding.Finally,the application verification of the robot friction stir welding system is made.First,the performance of the special electric spindle for robot friction stir welding is verified by the idling current of the electric spindle,the stability of the system and the axial force carried by the electric spindle;the 1-8mm plate thickness 6061 is used.-T6 aluminum alloy process test verifies the welding range of the system,and uses the upsetting force received by the stirring head during the welding process and the deformation of the robot tool axis in the Z direction to make the upsetting force position fitting analysis,using the stirring head in the welding process The lateral force received by the robot and the offset of the robot on the weld surface(the Y direction of the robot tool axis)are fitted to analyze the lateral force position.According to the deformation error compensation model based on the speed coordinate system,the welding of different plate thicknesses is made.Deformation prediction;then design process tests in different directions,analyze the stability of the system in different directions,and verify the application of the upsetting force position fitting analysis and the lateral force position fitting analysis made above;finally,the plane curve welding is used The process test and the welding of the complex space curved wall panel(satellite radiator)proved the stability and feasibility of the system.