Research On High Efficiency Machining Of Ablation Milling By Fast-moving Electrode

With the progress of science and technology and the development of society,the development of mechanical manufacturing is faster and faster.The materials of difficult machinability(such as high temperature alloy and titanium alloy)are manufactured and widely applied to the equipment manufacturing industry.And the EDM milling is an important branch of special machining,it uses the simple electrode and let the electrode moves like the traditional mechanical milling.The required shape and size of workpiece is machined by the sparks between the electrode and workpiece.This technique has no restrictions in hardness and strength of workpiece,also has the characteristics of multi axis linkage motion.So it has unique advantages in the process of machining complex cavity.However,the material removal efficiency is not high due to limited output energy of pulse power supply.In order to solve this problem,this paper proposes ablation milling by fast-moving electrode.It uses oxygen as the dielectric,and let the electrode suspended above the workpiece.First,it changed the energy source of material erosion,material is removed by the great chemical energy released from the burning of material;Second,it let the electrode suspended above the workpiece,spark discharge occurred at the bottom of the electrode,which makes it easier to realize the compensation of the electrode wear.The fast-moving and rotation of the electrode itself makes the machining more stable.Specific works were as follows:1)The system of ablation milling by fast-moving electrode was designed and built.Also the electrode rotation device,gas supply system,clamped device of workpiece and servo control device were designed.2)Research on the machining mechanism of ablation milling by fast-moving electrode.Analyze processing mechanism deeply mainly from energy sources,discharge channel formation process,the machining state,erosion particles,surface microstructure and so on.3)The comparative test for conventional EDM milling,EDM ablation milling,and ablation milling by fast moving electrode was performed in milling process under the same experimental conditions.The results show that the machining efficiency of ablation milling by fast moving electrode can reach 11.2 times of conventional EDM milling,and the relative tool wear ratio decreased by 86 %,which shows the advantages of the processing methods proposed in this paper in the material removal efficiency and electrode wear.4)With the die steel Cr12 as the processing material,the experimental research of ablation milling by fast moving electrode was carried out.The influence of the electrical parameters(pulse-on time,pulse-off time,low voltage current)and non-electric parameters(oxygen pressure)on the material removal efficiency and the relative loss of the electrode volume.The results show that with the increasing of discharge energy,the material removal efficiency increased and the relative tool wear ratio decreased.With the increasing of oxygen pressure,the intensity of combustion reaction increased,so the material removal efficiency increased.5)Verifying the processing characteristics of ablation milling by fast moving electrode through actual cavity machining,that is,good shape accuracy and size accuracy,as well as smooth transition between layers when processing complex surface.