tailieunhanh - Clarification of EDM gap phenomena using transparent electrodes

(BQ) This paper describes the heat source diameter of single pulse discharge in electrical discharge machining. To observe the discharge plasma, SiC and Ga2O3 single crystals were used as the electrode material since they are optically transparent and electrically conductive. It was found that plasma diameter expands within a few microseconds after dielectric breakdown and the plasma diameter is much larger than the discharge crater. From the measured diameter of the crater, the heat source diameter was obtained by solving the inverse problem of heat conduction analysis, and it was found that the heat source diameter is smaller than the plasma diameter but larger than the crater diameter. | CIRP Annals - Manufacturing Technology 63 (2014) 213–216 Contents lists available at ScienceDirect CIRP Annals - Manufacturing Technology jou rnal homep age : ht t p: // ees .e lse vi er . com /ci r p/ def a ult . asp Clarification of EDM gap phenomena using transparent electrodes Tomoo Kitamura, Masanori Kunieda (1)* Department of Precision Engineering, The University of Tokyo, Tokyo, Japan A R T I C L E I N F O A B S T R A C T Keywords: Electrical discharge machining (EDM) Temperature Transparent electrode This paper describes the heat source diameter of single pulse discharge in electrical discharge machining. To observe the discharge plasma, SiC and Ga2O3 single crystals were used as the electrode material since they are optically transparent and electrically conductive. It was found that plasma diameter expands within a few microseconds after dielectric breakdown and the plasma diameter is much larger than the discharge crater. From the measured diameter of the crater, the heat source diameter was obtained by solving the inverse problem of heat conduction analysis, and it was found that the heat source diameter is smaller than the plasma diameter but larger than the crater diameter. ß 2014 CIRP. 1. Introduction To understand the removal mechanism in electrical discharge machining (EDM), analysis of heat conduction in electrodes due to single pulse discharge is important. To obtain accurate temperature distribution in the electrodes however, correct boundary conditions should be used. The most critical boundary conditions are energy distribution ratio to the anode and cathode electrodes, and diameter of heat source [1]. The energy distribution ratio is the ratio of energy transferred to the anode and cathode to the total discharge energy, which can be obtained by solving the inverse problem combining temperature measurement and heat conduction analysis [1,2]. The other important boundary condition is the diameter of the heat source at the discharge spot.