Research On Piezoelectric Control Method For Micro-structured Surface Machining

Micro-structured surface refers to a surface with sub-micron level accuracy and a micro-topology shape with specific functions.Because of its excellent advantages of light weight,small size and low cost,it is currently widely used in the optical field,aerospace,military and other fields.The method of micro-structured surface processing has also become a research hotspot,and the processing technology for micro-structured surfaces is also developing rapidly.Among them,the fast tool servo machining technology is one of main methods for processing micro-structured surfaces due to its advantages of being able to process smooth and continuous asymmetric three-dimensional structures,machinable materials and high processing efficiency.During the processing of micro-structured surface,due to the surface features of the micro-structured surface,the cutting depth is a time-varying variable during the processing process,causing dynamic changes in cutting force,which results in instability in the processing process and may cause regenerative chatter happened.The occurrence of chatter vibration will have consequences such as the workpiece precision could not reach the standard,tool wear and so on.Therefore,it is of great significance to control chatter during machining.In this paper,the structural design of a fast servo tool post for micro-structured surface machining is firstly carried out,and the relevant components are selected and calculated to ensure that the design requirements are met.The actual performance of overall fast servo tool has been subjected to relevant static and dynamics simulations,and compared with the theoretical calculation results to ensure that the designed tool post meets the requirements of use and meets safety standards.Then,the mathematical model of regenerative chatter during micro-structured surface machining was performed,and the stability analysis of the machining process was performed according to the mathematical model.According to the established chatter mathematical model,the relevant cutting parameters were selected,and the cutting simulations was compared to observe the tool vibration when stable cutting and chatter occurred.Through the analysis of simulation results,the feature amount for detecting chatter occurrence was selected as the basis for judging the occurrence of chatter,and an experimental scheme for detecting the chatter of the tool was designed.Because piezoelectric materials have the advantages of fast response and large output force,active control experimental scheme that uses piezoelectric actuators to suppress chatter vibration during the processing is designed in this paper.Combined with the BP neural network control algorithm,through the input of chatter data,the output of control voltage can be obtained,the piezoelectric actuator is used to realize feedforward control of chatter of the tool.When designing a real-time feedback control scheme for chatter,the BP neural network control algorithm has its limitations.During the training process,it may fall into a local optimal situation,and the optimal control voltage cannot be obtained.Therefore,the traditional BP neural network algorithm was optimized by using particle swarm optimization.And two control experiment schemes are designed,and the uncontrolled chatter is compared with the vibration after control.The experimental results show that the two control methods have obtained perfect effect.