| Discharge ablation is a new type of high-efficiency electric machining method.Electric spark discharge is used to ignite the metal substrate,and the activated metal substrate and the oxygen between the electrodes undergo an oxidative combustion reaction,releasing a large amount of heat to etch the workpiece,which is difficult to process.Processing materials have great application prospects.However,under the condition of a single pulse of conventional electric spark,only one discharge channel is generated,and the energy is concentrated at one discharge point,resulting in a very ablation reaction and a low surface quality after material processing.In order to solve the contradiction between the surface quality of the workpiece and the processing efficiency,this paper combines multi-channel discharge and ablation processing.Because multi-channel discharge disperses the energy of the entire discharge circuit,it ignites the metal substrate and atomizes between the electrode and the inlet electrode.Oxygen in the medium undergoes an oxidative combustion reaction.Therefore,the ablation processing efficiency is improved while the surface quality of the workpiece is improved,and the contradiction between the processing efficiency and the surface quality of the workpiece is resolved.Major research contributions are as follow:(1)The whole experimental processing system is designed,and the system components include:atomization device,rotating electrode multi-channel ablation processing device.In addition,the internal and external structure of the processing device,the connection method between electrodes and series resistors,the power supply structure of the entire circuit,the internal cooling system of the device,and the electrode insulation treatment method are introduced in detail.(2)The mechanism of multi-channel discharge is analyzed,and the relationship between the number of discharge channels and the voltage and current in the circuit is derived.Design a multi-electrode discharge fixture and perform a single pulse discharge test.The characteristics of the discharge waveform and the discharge erosion pit are analyzed,and the characteristics of the voltage waveform showing a step-down and the current waveform step-up under a single pulse condition are obtained;in addition,the discharge pit is small and shallow due to the multi-point discharge dispersing the entire loop discharge energy,thereby improving the workpiece Surface Quality.A multi-electrode discharge fixture was used to test the number of single-pulse discharge channels.(3)The characteristics of multi-channel ablation processing under the condition of rotating electrode were studied.The main processing process of multi-channel ablation includes four parts:multi-point discharge of rotating electrode,multi-point activation of workpiece surface,metal oxidation combustion,and discharge of erosion products.From the perspective of energy absorption and utilization,as long as the continuous penetration of the inter-electrode atomizing medium is maintained,the ablation reaction can be ensured to continue.(4)The multi-channel discharge ablation process of rotating electrodes was studied.Using GH4169 as a workpiece,a multi-channel ablation and single-channel ablation comparison test was carried out.The experimental results show that the voltage and current waveforms in the multi-channel ablation continuous processing meet the characteristics of a single pulse multi-channel discharge waveform.In addition,the multi-channel discharge is generated randomly under continuous processing conditions;Erosion efficiency increased by 70.17%;multi-channel ablation due to multi-point discharge dissipates the discharge energy,so the surface quality of the workpiece after machining is greatly improved compared with single-channel ablation,and the number and width of surface microcracks are also greater than single-channel ablation Less and less eclipse.(5)The multi-channel ablation process technology was studied,and the effects of electrical parameters(pulse width,low voltage current)and non-electrical parameters(aerosol medium,electrode speed)on the material removal rate of the workpiece under the conditions of electrode rotation were analyzed. |
PDF Full Text Request