Electrode Clamping Mechanism For EDM Small Hole Drilling

Electrical Discharge Machining is a non-contact machining technique with little cutting force, which establishes its advantage station in the fields of small holes machining. In small hole drilling, the electrode has large erosion for its small section. So it has to frequently change electrode during machining process, and which will waste plenty of time when machining large quantities of small holes. So it has great significance to resolve the problem.The principles, features, applications and disadvantages of common electrode clamping mechanisms for small-hole-drilling are analyzed on the basis of a lot relevant literatures. Then a new clamping mechanism has been proposed in this paper.A clamping mechanism which can compensate the electrode erosion has been designed on the common EDM. The mechanism includes mechanical part and electrical part. The mechanical part consists of stepping motor, electromagnet, friction wheels and helical coil spring. The electrical part consists of AT89S51 SCM and drive circuit. The mechanism can clamp the electrode with the diameter from 0.20mm to 1mm and can hold the tiny rectangle section electrode. The mechanism can compensate the axial wear of electrode when electrode axial erosion affects the machining process. After the compensation, the electrode can machine the next process immediately. A long electrode clamped by the mechanism can machining a set of holes continuously, which shortened the assistant time and raised the efficiency in the process.Some correlative experiments have been done by the electrode clamp mechanism. The result analyses of the length of each compensation and reduplicate orientation accuracy show that the compensation error is less than 0.2mm and the reduplicate position error is less than 0.15mm.