Process and apparatus for controlling the concentration of solid particles in suspension in an EDM machining fluid

An apparatus for machining by electrical discharges an electrode workpiece by means of an electrode tool wherein a machining fluid is circulated through a machining zone between the electrodes, said machining fluid comprising electrically conductive solid particles in suspension in a liquid, and wherein voltage pulses are applied between said electrodes for triggering electrical discharges, said apparatus comprising means for measuring the average value of the delay time interval between applying a voltage pulse across the electrodes and an electrical discharge flowing acrsss said electrodes, means for establishing a first signal representative of said average value, means for establishing a second signal controling the concentration of solid particles in suspension in the machining fluid, means for comparing said first signal to a reference signal, means for adjustably varying said second signal as a function of the difference between said first signal and said reference signal, and means for varying the concentration of said solid particles in suspension in said machining liquid flow as a function of said second signal.

In an apparatus for electrical discharge machining of an electrode workpiece by an electrode tool wherein a machining fluid is circulated through a machining zone between the electrodes, said machining fluid comprising electrical conductive solid particles in suspension in a liquid, and wherein voltage pulses are applied across the electrodes for triggering delayed electrical discharges and the concentration of particles in the machining fluid is varied as a function of a machining parameter, the improvement comprising means for measuring the average triggering delay of said electrical discharges, and means for varying said concentration of solid particles for maintaining the average triggering delay of said electrical discharges within predetermined limits.

A method for machining by electrical discharges an electrode workpiece by means of an electrode tool wherein a machining fluid is circulated through a machining zone between the electrodes, said machining fluid comprising electrically conductive solid particles in suspension in a liquid, and wherein voltage pulses are applied between said electrodes for triggering electrical discharges, said method comprising measuring the average value of the delay time interval between applying a voltage pulse across the electrodes and an electrical discharge flowing across said electrodes, establishing a first signal representative of said average value, establishing a second signal controlling the concentration of solid particles in suspension in the machining fluid, comparing said first signal to a reference signal, adjustably varying said second signal as a function of the difference between said first signal and said reference signal, and varying the concentration of said solid particles in suspension in said machining liquid fluid as a function of said second signal.