APPARATUS AND METHOD FOR FORMING A VARIABLE DIAMETER HOLE IN A CONDUCTIVE WORKPIECE

Abstract

A method and apparatus for forming a passage with a variable diameter along its length in a conductive workpiece are disclosed. The workpiece is mounted in a fixture and an externally insulated hollow electrode is positioned proximate to a surface location of the workpiece into which the passage is to be formed. A first selected voltage is connected between the electrode and the workplace with the voltage being connected to cause the electrode to act as a cathode and the workpiece to act as an anode. A pump causes an acidic electrolyte to flow through the electrode at a chosen pressure and onto the workpiece surface. The electrode is moved toward the workpiece at a first selected feed rate by a CNC controller to cause a portion of the passage to be formed at a first predetermined diameter. The CNC controller causes at least one of the first selected DC voltage to switch to a different selected DC voltage or the first selected feed rate to switch to a different selected feed rate when a predetermined depth is sensed by an encoder to cause another portion of the passage to be drilled at a second predetermined diameter.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1LAWRENCE J. SCHRODER