Device for quality decision of a machining state of an electric spark machine

A device for quality decision of a machining state of an electric spark machine applying voltage in a pulse form to a machining space between an electrode and a workpiece for contour machining by pulse discharging, said device comprising:

• a plurality of machining state detection means each of which detects a physical quantity denoting individual machining states, the physical quantity detected by any one of said machining state detection means being different from the physical quantity detected by any other of said machining state detection means, wherein the physical quantities are:
• machining speed;
• machining voltage;
• machining current;
• on and off times of voltage applied to an electrode;
• total number of discharges, number of abnormal discharges;
• abnormal discharging rate;
• and discharging frequency, and further wherein the standard value of each physical quantity is set according to machining trajectory shapes and machining modes;
• at least one data table, in which quality evaluation of a machining state is previously determined based on ratios of at least two physical quantities detected by the machining state detection means with corresponding standard values;
• and
• a machining state quality decision means which performs quality decision of the machining state, based on machining state quality evaluations in the data table ratios of at least two physical quantities with corresponding standard values, wherein said machining state evaluation and quality decision means synthetically evaluates the machining states, using a combination of comparison results for at least two of the physical quantities and performs the quality decision of the machining state.