Electro-erosion machine tools and head assemblies therefor

Electro-erosion apparatus of the type in which an elongated tool electrode (1) is moved under tension between first and second head assemblies (5a, 5b) for performing an electro-erosion work process on a workpiece (2) wherein

• the workpiece is disposed between said head assemblies,
• each said head assemblies includes
• means (300a, 300b) for making electrical contact to said electrode and each of said head assemblies further includes means directing scavenging fluid to the electro-erosion location working gap,
• wherein each of said assemblies comprises a housing;
• fluid inlet means (200a, 200b) leading to the interior of the respective housing for passing scavenging fluid (7a, 7b) to the respective interior of the respective housing to fill the respective housing;
• an outlet nozzle (303) defining an opening between the interior and the exterior of the respective housing through which a tool electrode can pass from one housing to the other, and through which scavenging fluid also can pass from the interior of the respective housing as an envelope surrounding and in contact with said tool electrode, and being directed toward the workpiece;
• electrical contacts (300a, 300b) mounted in the respective interior of the respective housing and being cooled by the scavenging fluid therein and in electrical contact engagement with said tool electrode;
• and tool electrode guide means (100a, 100b) mounted in the interior of the respective housing, each guide means being cooled by the scavenging fluid within the respective housing and guiding said tool electrode in its path through said outlet means, at least one of said guide means comprising two support members (101, 102), two parallel pivot pins (119) attached to respective ones of said support members, a first set of polygonal guide plates (115, 116) rotatably mounted one above another on one of said pivot pins, and a second set of polygonal guide plates (117, 118) rotatably mounted one above another on the other of said pivot pins, said plates being so arranged in relation to one another that edge portions thereof bound a space in which said tool electrode can be located so that said edge portions are in sliding contact with said tool electrode and such that, for each plate, there is another one of said plates which is at the same level on said pivot pins and which contacts said tool electrode on the opposite side thereof.