Patent ID: 7255829

Claim:
An apparatus for the thermal treatment of metallic workpieces or a plurality of stacks formed of metallic workpieces arranged one above the other, said apparatus comprising: a quenching chamber for receiving preheated workpieces and a quenching gas for cooling same; guide channels each for guiding a directed flow of quenching gas about a respective one of said workpieces or said stacks of said workpieces, wherein each of said guide channels has a closed lateral surface and a length that corresponds at least to a height of the respective individual or stacked ones of said workpieces and each of said guide channels surrounds a respective one of said individual workpieces or said stacks of said workpieces along a direction of flow of said quenching gas such that the respective guide channel guides said quenching gas to flow longitudinally past the respective one of said workpieces or said stacks of said workpieces; and a quenching gas closed loop circulation assembly associated with said quenching chamber for circulating said quenching gas along a closed loop circulation path through said quenching chamber.