Study On The Influence Of Pulse Current Mode In Pulse Dynamic Electrochemical Machining Process

Pulse dynamic electrolysis machining is a kind of precision electrolytic machining method.It combines pulse current and tool vibration organically.The pulse dynamic process is a pulse quasiequilibrium process,which is different from a continuous equilibrium status in a traditional electrochemical machining process.Electrolysis products accumulation in the machining gap could be reduced and the transient time from the initial machining state to the equilibrium machining state could be minimized.The machining precision will be improved significantly.However,the anodic electrolysis products,bubbles and Joule heat are produced in a complex pulse dynamic process.The influence of pulse current and tool cathode vibration in the machining process need to be discovered.Therefore,the effect of pulse current and tool vibration in machining process was studied in this paper.The main research work is as follows:(1)The influence of pulse current mode on the current density of ECM was revealed.In the pulse dynamic ECM process with small gaps,the current decreases rapidly after reaching the peak and maintains a low current state.It is not conducive to the improvement of machining accuracy and surface quality.In order to improve this situation,the simulation and experimental study on the pressure of electrolyte inlet were carried out.The simulation and test results show that increasing the electrolyte pressure has almost no improvement on the current.Based on the reasonable arrangement of the pulse current period and the control of the stacking degree of the products,the experimental research on the two modes of pulse current was carried out.The experimental results show that compared with the grouping pulse mode the small opening angle mode increases the current density significantly.A comparative experiment of grouping pulse and small opening angle power machining was carried out.The experimental results show that the small opening angle current mode has better machining accuracy and surface quality.(2)The influence of pulse current mode on side stray corrosion is clarified.In the dynamic ECM of sub-millimeter scale group grooves,the ribs between the grooves are seriously corroded by the stray current on the side of grooves.In order to reduces stray corrosion,the electric field simulation of machining process was carried out.The simulation results show that the relative dynamic position of the tool cathode in the slot has a great influence on the stray current of the side wall.The greater the distance between the bottom of the cathode and the grooves,the greater the area of influence and stronger stray current.The experiments of grouping pulse and small opening angle were carried out.The experimental results showed that the small opening angle mode significantly reduced the stray corrosion on side wall.(3)The deformation analysis of weak rigid blade in two-sided dynamic ECM was carried out.The deformation measurement system of workpiece is established,and the deformation of weak rigid blade under different cathode vibration frequency and machining gaps difference was measured.The experimental results show that the clearance difference on the blade basin and back of the blade is the key factor affecting the blade deformation.Therefore,a step machining method is proposed for the blade with uneven margin of blade basin and back of the blade.First,feeding the tools with variable speed to reduce machining allowance difference on both sides of blade.Second,the same feeding rate is used until the end of the processing.The contrast tests between the traditional differential feeding and two step feeding mode are carried out.The experimental results show that the specimen has higher profile accuracy in the two step feeding mode.