Simulation And Experimental Research On Counter-rotating Electrochemical Machining Of Surface Convex On Revolving Parts

Aero-engine casing parts is a kind of the thin-wall revolving work-piece with complex structure and material of difficult machining. And the machining technology of the casing parts has been the key parts in aero-engine manufacturing. There are some problems such as the deformation of the thin-wall parts,low machining efficiency and high tool costs in conventional CNC machining of the thin-wall parts. Electrochemical machining method has become an effective method for solving these problems. Because it has many advantages such as no stress machined surface, no restrictions in material strength and hardness, etc. For the convex structure on the revolving work-piece,the technology of Counter-Rotating Electrochemical Machining has been used to study the forming accuracy.Stray corrosion is an important factor in the influence of the Counter-Rotating electrochemical machining accuracy. It is the stray current on the surface of the convex that cause the stray corrosion. The stray corrosion leads to the error of the surface profile of the convex. The larger the error of the surface profile of the convex is, the more serious the stray corrosion is.To study the convex profile on super-alloy anode, a finite element model based on electric field that describe the Counter-Rotating Electrochemical Machining processing has been developed. The analytical program is compiled based on the APDL language provided by ANSYS. The simulation has been carried out with the influence of different height of the convex and different voltage, feed rate and different radius of the cathode on the error of the surface profile of the convex. The simulation results show that with the increase of the height of the convex and the voltage,the error of the surface profile is also increasing. With the increase of the feed rate, the machining gap will become small and the error of the surface profile of the convex will also become small. The influence of the variation of the cathode radius on the error of the surface profile is changing. With the increase of the radius of the cathode, the error of the center section of the convex surface profile is reduced. But the error of the sides of the surface profile is increased. At the same time, the influence of different voltage, feed rate and the radius of the cathode on the height of the forming profile of the convex has been also simulated. The simulation results show that the higher the voltage and the larger of the radius of the cathode is, the larger of the height of the profile of the convex become. And the faster the feed rate is,the lower of the height of the profile of the convex become.In order to reduce the stray corrosion on the surface of the convex, the auxiliary anode with positive voltage has been designed and added in the window of the cathode. The auxiliary anode can change the distribution of the electric field of the non-processing field and reduce the current density of the convex surface to reduce the stray corrosion. The local dimension of the auxiliary anode is optimized so that the auxiliary anode can play a better role. The simulation of the effect of the auxiliary anode with different positive potential on the current density of the surface of the convex has been carried out. The simulation results show that when the voltage of the auxiliary anode and the convex is equal, the current density is significantly reduced. And when the voltage of the auxiliary anode is higher than the convex, the current direction of the convex changes and the stray corrosion does not occur.The cylindrical work-piece fixture has been optimal designed in Counter-Rotating electrochemical machining, so that it can meet the requirements of processing of the large height of the convex. The experiments have been carried out using auxiliary anode applied with different positive voltage. The experimental results show that when the voltage of the convex and the auxiliary anode is equal and the height of the convex is low, the stray corrosion is effectively retrained. But when the height of the convex is large, the effect is not obvious. When the voltage of the auxiliary anode is higher than the convex, the experiments have also been carried out.The experimental results show that when the height of the convex is large, the stray corrosion is also restrained obviously. In addition, the conical work-piece fixture has been also designed, and the exploratory experiment of convex on the conical surface has been also carried out.