Investigation On Multi-physics Coupling Theory And Technology Of High Frequency Pulse Electrochemical Precision Machining

Pulse electrochemical machining(PECM)has been pivotal manufacturing technology for aerospace,weaponry and automobile industry,because of its advantages and particular characteristics.However,a wide variety of physical fields have an influence on the ECM process and machining precision,such as electric field,flow field,temperature field,and so on.Moreover,the relationship of each fields is complicated,which results on the longer preparation period of ECM and the higher research costs.Therefore,it is difficult for ECM industry to popularize.However,application of computer simulation technology in simulation of ECM process and optimization design of cathode is important to solve the problems and is of great significance.In this dissertation,several key problems of multi-physics coupling theory of high frequency pulse electrochemical precision machining were carried on the thorough analysis and research.The main research content is as follows:(1)According to the basic principle of PECM and the theory of multi-physics coupling,the influence of fields on PECM process was analyzed and coupling types of each field were defined,which can theoretically support establishment of multi-physics coupling model of PECM.(2)According to the interaction mechanism between various physical fields in PECM,coupling model of temperature field was established,to solve temperature distribution of machining system.However,in PECM,for the time scale of the applied pulses is orders of magnitude smaller than the time scale of temperature conduction in the electrodes,simulation of the temperature evolution would be a computationally very expensive procedure.To solve the problem,a quasi steady state algorithm based on time average was introduced to quickly calculate temperature distribution of the system in quasi steady state.Moreover,using the method,the influence of machining parameters on temperature distribution of the system was researched.(3)Based on coupling model of temperature field in PECM,a simplified algorithm was presented to simulate the PECM process and investigate field changes with the PECM process.Moreover,accuracy of simplified algorithm was compared with accuracy of the full time algorithm and using the compressor blade as research object,the simplified algorithm was verified by experiment.(4)According to matching between movement way of cathode and supply way of pulse power,the influence of pulse parameter on design of cathode was introduced and design method of cathode based on change model of gap was presented,to analyze the influence of pulse parameter on the gap size.Moreover,in practice,electr,olyte conductivity is constantly changing.Therefore,to more accurately design the cathode,optimization design method of cathode based on multi-physics coupling algorithm was presented.The optimization design method was that cathode boundary was adjusted constantly by method of iteration before meeting the design accuracy.(5)The relevant fixtures were designed and optimization design method of cathode was verified.Moreover,the problems appeared in the experiments were analyzed and the effective solution was given.The results show the machining precision of workpiece was improved from 0.2 mm to 0.06 mm,using optimization design method of cathode.Therefore,it can effectively prove that optimization design method of cathode is valid and effective.