Abstract: An electrical discharge machining apparatus in which a workpiece is machined by generating an electrical discharge between the workpiece and a facing electrode immersed in a machining liquid. A blower is provided for forcing cooling air into the interior of a bed, a column, and a head of the apparatus to prevent thermal displacements between the electrode and the workpiece and thus ensure accurate machining. The blower may also be used to cool the machining liquid.

Abstract: An electrical discharge machining apparatus having an improved bed which provides improved control over the gap between a machining head and a workpiece by reducing the amount of deformation produced in the bed when the table and saddle are moved. The bed is constituted by an upper plate and side plates, with saddle guide rails being disposed on the upper plate, a saddle movably mounted on the saddle guide rails, table guide rails mounted on the saddle, and a workpiece-supporting table movably mounted on the saddle guide rails. In accordance with one embodiment of the invention, the saddle guide rails are positioned at the edges of the upper plate, directly above the side plates of the bed. In another embodiment, reinforcing members are provided under the upper plate, extending parallel to and directly under respective ones of guide rails.