Basic Research On Development And Control Of Gap In Electrochemical Machining With A Floating Cathode

The fundamental principle of improving machining accuracy and surface roughness in electrochemical machining(EMC)is to control the removal difference,this difference is caused by the non-uniformity of the inter-electrode gap,which is influenced by anode bump roughness related to inter-electrode gap.Therefore the inter-electrode gap is the key parameter in EMC.The inter-electrode gap does not only influence the machining precision and surface quality,but also the machining efficiency and stability.On the other hand,gap is interlinked with electromagnetism and electrolyte,it influences electromagnetism and electrolyte’s characteristic.Therefore the monitoring,regulation and control the gap has been the key topic that ECM experts and scholars have endeavored to investigate.However the development and control of the gap is mainly achieved by external institution,A good method has not been found to resolve copying error,repeated error and uncontrollable machining process resulted by instable variation of gap at present.Especially,the research and application of small gap EMC has been applied increasingly widely to improve machining precision,the accuracy of gap monitoring and sensitivity of gap control play significant roles,therefore how to develop,monitor and effectively control the gap is the hot topic in EMC.In this paper we proposed the method in EMC of applying floating cathode to form the machining gap and controlling the gap by adjusting float rate.The interactive relation among flow,voltage and gap is investigated,and the gap model is established on this relation.The model of floating cathode electrochemical machining is proposed based on fluid mechanics and electrochemical related theory.The experimental device is designed,the impact of electromagnetism and electrolyte on gap is achieved and the basic data is obtained,which is based on plane processing.The electrolyte’ characteristic of gap is analyzed by FLUENT,and the model is improved combined with experimental data.At last,the verification experiment is carried on.This research showed that the cathode can float on the anode surface when the gap achieves state of equilibrium,where the cathode’ gravity and support force are balanced.It is also noticed that electromagnetism has influence on gap and electrolyte,when the voltage increases,the gap and the flow increase.Therefore,our method is a kind of feasible gap adjustment method by controlling the flow to control floating cathode machining gap.