Research On Motion Controller And Servo Control Strategy Of WEDM Based On Interpolated Byte Stream

With the continuous development of electrical machining technology,the proportion of WEDM in the field of mechanical manufacturing is increasing in the world,and the related research results are emerging.As a cheap and widely used machine tool,the pursuit of efficient and stable machining has become an important research direction.Motion control system is an extremely important part of WEDM.This topic will start from this direction to develop a motion controller which can be applied to most of WEDM,in order to achieve high efficiency and high stability machining.The specific work is as follows:Based on the in-depth study of motion control technology,this paper proposes a motion controller of WEDM based on interpolation byte stream.The motion controller takes FPGA as the main control chip,adopts UART communication in serial communication,and uses interpolation byte stream to transmit signal to the motor.The interpolation operation function is transferred to the host computer,and the motion controller transfers the data to the host computer After interpolation,the data is stored and read,and then converted into the motion signal of stepper motor.According to the functional requirements and performance requirements of WEDM,the required hardware circuits are modularized and classified.Using Altium designer software for schematic design,including FPGA minimum system circuit,communication circuit,I / O signal circuit,etc.And complete the drawing and production of PCB and the welding of components and circuit board debugging.Based on the principle of generality and convenience,the internal structure of "communication board + adapter board + relay board" is adopted,which not only saves the internal space of the controller,but also makes the controller scalable and compatible with other types of machine tools.From the perspective of system integration,using FPGA chip EP4CE10F17C8 N as the platform,the UART serial communication,stepper motor precise control,servo feed strategy realization,pulse power waveform generation and numerous switch signal control are realized by programming.Based on the threshold voltage method,a new servo feed strategy for EDM is proposed.The average voltage collected between electrodes is converted into frequency signal.According to the returned pulse frequency and the preset threshold,the inter electrode discharge state in the detection cycle can be judged,and each discharge state corresponds to a servo feed action.In order to verify the performance of the motion controller and the feasibility of the servo strategy,the following experiments are designed:Firstly,the characteristics of discharge servo parameters in the servo strategy are explored,and the influence of threshold and detection period on machining efficiency and discharge state are obtained.The experimental results show that under the same conditions,when the detection period is 0.5s,higher processing efficiency can be achieved;under the same conditions,when the acceleration zone accounts for 50% ? 60%,and the uniform velocity zone accounts for 30%,higher processing efficiency can be achieved.Secondly,in order to better verify the performance of the motion controller and improve the servo strategy,three servo processing modes are designed,and five common types of workpieces are used for experiments,and the processing efficiency,workpiece surface roughness and real-time feed rate in the processing process are analyzed.Finally,a complete shape cutting experiment is carried out to analyze the dimensional accuracy and shape integrity of the workpiece after cutting.The motion controller of WEDM designed in this paper has beautiful appearance,easy to use and complete functions.In the process of experiment,the functions of workpiece machining,servo feed control and switch signal control are fully realized.