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Fail Safe Electrical Discharge Machine Disclosure Number: IPCOM000083133D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 34K

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Iwata, PG: AUTHOR [+1]


An electrical discharge machine (EDM) is made fail-safe by adding a check valve.

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Fail Safe Electrical Discharge Machine

An electrical discharge machine (EDM) is made fail-safe by adding a check valve.

During machining, an electrode is fed toward a workpiece at a controlled rate. The exact spacing between the machined opening in the workpiece and the electrode is critical. This opening is maintained by comparing the actual voltage across the gap to a desired voltage, for a predetermined electrode-to-workpiece spacing. A servo senses the difference between the actual and desired gap voltages, and hydraulically controls the position of the electrode by adjusting a piston in a cylinder.

A power failure will, however, cause hydraulic pump pressure to drop, crashing the electrode into the workpiece. Insertion of a pilot-operated check valve in the hydraulic line to the bottom portion of the cylinder will prevent this. The valve is held open by pump pressure to permit normal machine operation. If power fails, the pump pressure will drop and the valve will close to prevent the piston from dropping the electrode onto the workpiece.


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