Apparatus for hardening metallic workpieces including furnace and workpiece transport structure, a part of which can remain in the furnace during furnace operation

An apparatus for the treatment of a workpiece which comprises:

• a furnace defining a treatment chamber therein, said furnace including a hollow body having opposite side walls, a rear wall and an open end opposite said rear wall, said side walls including elongated slots extending from the open end of said hollow body toward the rear wall, a door pivotally connected to said hollow body to open or close the open end thereof, upper and lower heating means located within said treatment chamber, two electrodes located within said treatment chamber between said upper and lower heating means, one of said electrodes being cup-shaped, the open end of which faces the open end of said hollow body, and two electrical lines, each of said electrical lines being attached at one of its ends to a respective electrode and then extending through an electrically insulated opening in said hollow body so as to be connected to a voltage source located outside of said hollow body, each said electrical line being electrically insulated from all other elements of the furnace, and
• a transport structure, said transport structure being movable with respect to said furnace and including a metallic mounting portion and a metallic platform portion, said platform portion being electrically insulated from said mounting portion, and said transport structure being constructed such that said mounting portion is located outside of said hollow body when said transport structure is moved with respect to said furnace such that said platform portion, which at least initially supports the metallic workpiece to be treated, is operatively positioned within said treatment chamber and the door of said furnace is pivoted to close the open end of said furnace and such that parts of said transport structure extend through the elongated slots in said opposite side walls of said hollow chamber.