Study On Motion Control Of Mirror Milling Equipment For Large Thin-walled Parts

The aerospace technology has been rapidly developed in our country.In order to work longer hours in space,the integrated thin-walled parts are widely used as parts of heavy rocket engine nozzles,propellant common bottom components,and fuel tank tube wall,because it is light and can reduce the assembly time and improve assembly quality.However,these thin-walled parts usually have large geometry,complex shape,low stiffness,high material removal ratio,and long processing cycle.Compared with chemical milling and copying milling,mirror milling will become the mainstream machining method due to its advantages of good generality,high efficiency,and no pollution.The control system and the auxiliary service programs have been designed and realized according to the characteristics of the mirror milling system of large thin-walled parts.And the key control problem of mirror milling system has been mainly discussed in this paper.The construction of mirror milling equipment control system has been completed according to the actual situation.The servo motors have been tuned and the parameters of frequency converter have been set.The working principle of the core hardware,motion controller,of the control system is analyzed.Based on the working principle,the system auxiliary service programs are designed and developed.The contour control problem of series shafts has been studied.Based on the traditional contour error estimation models,the conditions under which the contour error estimation is effective are analyzed.A neighbor-zone comparison strategy has been proposed to improve the accuracy of contour error estimation.Based on the traditional contour error estimation models,improved estimation algorithms have been put forward.The X-Y stage is utilized,and the experimental results show the effectiveness of the modified methods.Furthermore,comparing with the advanced contour error estimation methods,the error indices show that the proposed strategy possess the merits of easy realization and universality.Secondly,aiming at the problem of parallel axis synchronous control,the design process of synchronization controller has been divided into two parts: the design of single axis tracking controller and the design of synchronization control structure between axes.It is proved that the designed terminal sliding mode-adaptive fuzzy tracking controller is effective based on the Lyapunov stability theory.By using the Matlab/Simulink simulation platform,the performance of the designed controller has been compared with that of the classical PID controller.And it has been proved that the designed controller has a good tracking ability.Combining with the cross-coupling structure,the synchronization accuracy between the two axes has been improved obviously.The mirror processing equipment for large thin-walled components is used as the experimental platform.The motion control algorithm is programmed based on the upper computer software used in the machining platform.The contour control experiments of series shafts and the synchronous control experiments of mirror shafts are designed.Through the analysis of the results of two experimental data,it is proved that the motion control strategy proposed in this paper can provide support for the processing precision of the equipment.