Research On Friction Welding Phase Control Method Based On Model Reference Robust Adaptive

Phase friction welding is a metal solid phase welding technology.It has excellent welding advantages compared with common welding technology,and its application range is expanding.The existing phase control of friction welding mainly adopts PID control,which has great limitations on the more complex structure and diversified workpiece materials.In order to meet the requirements of welding versatility,welding process stability and precise phase control of friction welding machine,this paper Based on the existing research foundation and test platform,a new phase friction welding test machine and its control strategy are proposed.The main contents of this article are as follows:Firstly,by analyzing the welding characteristics of each stage in friction welding,the existing phase friction welding test machine is analyzed and optimized.A new phase friction welding test machine design scheme is proposed,which can be based on the specific dimensions of the workpiece.The mounting position is adjusted to enhance stability during the welding process.The finite element analysis of the main structure of the phase friction welding test machine is carried out to verify that the strength and deformation amount meet the requirements of the actual welding work,and the overall design of the control system and the selection of the main components are carried out.Secondly,the mathematical model of the permanent magnet synchronous servo motor is established,and the simulation model of the servo motor is established in Matlab/Simulink.The advantages and disadvantages of the mainstream friction model are analyzed and the LuGre friction model is adopted.According to the characteristics of the phase friction control during the friction heating phase,there is no phase control requirement.The simulation results also show that the LuGre friction model and the static model have smaller error when the speed is higher,so the model in the LuGre friction model can be used in the higher speed state.Equivalent to static friction,the improved model can reduce the amount of calculation under the premise of ensuring the accuracy of phase control.Thirdly,the control process of model reference adaptive control and backstepping control is analyzed.A control strategy combining two control ideas is proposed.The unknown parameter values ? ? obtained by the state observer are used for friction compensation,and the structure and control rate of the controller are designed.The form of the control signal under the defined function makes the control process meet the requirements of convergence.Finally,the simulation model of the system is established in Matlab/Simulink.The unit step signal and sinusoidal signal are used as the input signals of the system.For different types of welding workpieces,the PID control method will produce overshoot and hysteresis for different workpieces,and the proposed model reference The robust adaptive control output can always follow the response of the reference model.The control accuracy of the system is greatly improved compared with the PID control,and the control accuracy is kept within 0.45%.The control software of the upper computer is programmed to carry out the welding test on the workpiece.The results show that the strength of the workpiece after welding is the same as or better than the strength of the original workpiece,and the phase control accuracy is within 0.06°.