Method of and apparatus for increasing the productivity of an electroerosion drill

An improved drilling apparatus for electroerosively machining a small and deep hole through a workpiece, the drilling apparatus comprising a worktable for receiving the workpiece;

• a chuck and electrode guide for receiving and securing an elongated and thin tubular electrode, the tubular electrode having a first end which is juxtaposable with the workpiece to establish an electroerosion machining gap therebetween, the tubular electrode also having a hollow inner bore and an outer surface which are both coaxial with a longitudinal axis of the tubular electrode;
• a fluid supply and pump for supplying a first flow of machining fluid to the inner bore of the tubular electrode and through the inner bore of the tubular electrode into the machining gap established between the first end of the tubular electrode and the workpiece;
• a power supply for applying a series of electrical machining pulses between the tubular electrode and the workpiece to cause time-spaced electrical discharges across the machining gap thereby electroerosively removing material from the workpiece;
• and an electrode feed mechanism for relatively displacing the tubular electrode with respect to the workpiece to maintain the machining gap between the first end of the tubular electrode and the workpiece, and for advancing the first end of the tubular electrode into the workpiece;
• wherein the improvement comprises:
• a flushing nozzle spaced apart from the workpiece arranged about the tubular electrode for directing a second flow of the machining fluid along the outer surface of and coaxially with the longitudinal axis of the tubular electrode toward the machining gap;
• and
• a secondary machining fluid control for supplying the second flow of the machining fluid to the flushing nozzle during piercing of the workpiece by the tubular electrode, whereby machining speed is not drastically reduced as the tubular electrode pierces through the workpiece.

A drilling apparatus for electroerosively machining a small and deep hole through a workpiece, said drilling apparatus comprising:

• a worktable for receiving a workpiece;
• a chuck and electrode guide for receiving and securing an elongated and thin tubular electrode, the tubular electrode having a first end which is juxtaposable with the workpiece to establish an electroerosion machining gap therebetween, the tubular electrode also having a hollow inner bore and an outer surface which are both coaxial with a longitudinal axis of the tubular electrode;
• a fluid supply and pump for supplying a first flow of machining fluid to the inner bore of the tubular electrode and through the inner bore of the tubular electrode into the machining gap established between the first end of the tubular electrode and the workpiece;
• a power supply for applying a series of electrical machining pulses between the tubular electrode and the workpiece to cause time-spaced electrical discharges across the machining gap thereby electroerosively removing material from the workpiece;
• an electrode feed mechanism for relatively displacing the tubular electrode with respect to the workpiece to maintain the machining gap between the first end of the tubular electrode and the workpiece, and for advancing the first end of the tubular electrode into the workpiece;
• a flushing nozzle spaced apart from the workpiece arranged about the tubular electrode for directing a second flow of the machining fluid along the outer surface of and coaxially with the longitudinal axis of the tubular electrode toward the machining gap;
• and
• a secondary machining fluid control for supplying the second flow of the machining fluid to the flushing nozzle during piercing of the workpiece by the tubular electrode, whereby machining speed is not drastically reduced as the tubular electrode pierces through the workpiece.