Workpiece holder apparatus

Abstract

A high-temperature electrochemical etching apparatus containing a workpiece holder, which contains a first base plate and a second base plate to be joined together by screws, the first base plate having a recess on the front face thereof for receiving and retaining the workpiece, and both the first and second plates having a through hole to receive a contact electrode, which is electrically connected to a conductor wire. The second base plate has a protective wire sleeve fixedly inserted therein to allow the conductor wire to conduct electricity to the workpiece in a protectively sealed manner. A memory alloy coil and a buffer spring are provided between the contact electrode and the conductor wire in such a manner that the contact electrode is in a normally removed position from the workpiece until during high-temperature electrochemical etching operations, at which time, the memory alloy coil will expand thereby allowing electric voltage to be transferred to the workpiece. This feature prevents the workpiece from being cracked, which was often caused due to the unevenness of the workpiece, when the workpiece holder is tightened together. The unintended portions of the workpiece, as well as the rear and side portions thereof, are protected from the highly corrosive etching fluid by first and second O-rings. The first O-ring, which receives a compressional force when the workpiece holder is tightened, does not directly act on the workpiece. Rather, the compressional force acting on the first O-ring is transferred via a slanted surface to a second O-ring, which then acts on the workpiece. Since the force acting on the workpiece is not perpendicular to its surface, the possibility of cracking the workpiece is further minimized.