Die-sinking type electrical discharge machining method and apparatus of the water-oil-write

摘要

PURPOSE:To remove water approximately completely from the machining section of a workpiece, when machining fluid is changed from water to oil by removing residual water from the machining section via an electric discharge machining process. CONSTITUTION:After water is used as rough machining fluid, water in a machining tank T is discharged. Also, a water-oil selection signal is outputted from CPU 60, and pumps P1 and P2 are driven, thereby feeding oil to the tank T. Then, machining depth D is set at a value slightly less than a shape obtainable after finish machining with oil. Furthermore, an instruction is sent from the CPU 60 for keeping an electrode EL at a present position, or for preventing the electrode EL from lowering over the set machining depth D, and a machining process takes place in a water removal condition. According to the electric discharge, the temperature of water within a gap rises and water changes into bubbles. Also, water tuns into fine particles, due to pressure generated at the time of electric discharge, and leaves the gap together with the bubbles. In this case, the pump P2 may be intermittently driven to cause an intermittent oil jet, thereby facilitating the removal of water from the gap.