Research On The Detection Of Discharge State And Servo Control Strategy Of Portable EDM

The significance of the manufacturing industry has become a demand with a high rate,however,started to develop in the direction of precision due to the improvement of people's livelihood recently.The micro-hole structure is common in space shuttles and medical equipment,and it is difficult to use traditional machining.However,EDM has the characteristics of no macroscopic mechanical cutting force,high processing accuracy and is widely used in small hole processing.The key to the discharge state detection and servo control system in EDM is to ensure the stable and efficient processing of EDM.Therefore,according to the characteristics of strong randomness in the EDM process,this paper has produced a high-precision discharge state detection device and servo control strategy,which is of great significance to ensure the processing quality and processing efficiency.This paper is tend to describe the current research status of discharge state detection and servo control strategies at home and at abroad,and then to analyzes the advantages and disadvantages of different methods of discharge state detection and servo control.Mathematical modeling and the characteristics of the parameters of the entire processing system that change with the processing time Servo control strategy of fuzzy PID control.The current voltage and wave forms under typical discharge states were collected based on the experimental method and the law was sought,then the characteristics of the voltage and current signals under different state were analyzed.The artificial marks were open circuit,partial open circuit,spark state,short circuit and short circuit.A variety of different discharge states,and the overall scheme based on the lower computer collecting gap discharge signals and the upper computer identifying the given discharge state.The key component were selected,therefore,a lower computer system based on an ARM that can collect electrical signals of the discharge gap at high speed was designed and built..The real-time performance of the entire lower computer system is analyzed to ensure the real-time performance and accuracy of the collection.Through the serial port and DMA,the electrical signal of the discharge gap was sent to the upper computer in real-time.In the host computer,the voltage signal and current signal of the discharge gap were used as the input of the neural network,and the five different discharge states are used as the input of the neural network.A three-layer neural network structure was used for discharge state detection.Through experiments,the neural network structures of different numbers of hidden layer nodes were compared.Finally,the neural network structure was uniquely determined,whereby quickly determine the discharge state in each control cycle in real-time.In terms of the servo control strategy,provided the problem that the spark discharge voltage is not constant with the increase of the machining depth during EDM,a control system that uses the difference between the open circuit rate and the short circuit rate as the input of the control system was proposed.However,due to the difficulty of mathematical modeling and time-varying characteristics in EDM,the method of intelligent control theory was used,and the neural network,expert control,and fuzzy control in intelligent control were compared and finally determined to use fuzzy control and cooperate with the project.The commonly used PID control theory was used in the servo control strategy of EDM.It has been verified that the servo system based on fuzzy control can not only automatically adjust the PID parameters according to different discharge states,but also achieve the purpose of automatically adjusting the feed speed,thereby reducing the phenomenon of short circuit retreat and improving the processing efficiency and processing quality.Last but not the least,the discharge state detection system and the corresponding host computer system was developed,and the discharge state d etection system was tested for different power sources.The tested results showed that the detection system's ability to detect partial open and short circuits is more than the original threshold.The detection method has been greatly improved inaccuracy,and whereby compared with the original PID control and fuzzy PID.PID parameters can be set online to reduce the short-circuit retreat of the machine tool,thereby improving the efficiency and quality of the entire EDM.Because of the entire discharge stat e detection system and servo control system were mostly implemented by software algorithms,reducing the complexity and redundant hardware circuits,the entire EDM machine tool have also been greatly improved in portability.