Method and apparatus for heat treating metallic workpieces using a

Abstract

A method of heat treating metallic workpieces using a continuous-heating, sher-type, or gravity-discharge furnace having at least two treatment chambers through which the workpieces successively pass. The chambers, which are provided with doors, serve to respectively heat treat a plurality of workpieces charges, with individual ones of the charges being cyclically received by the respective chambers, being conveyed through the latter while heat treatment is undertaken, and subsequently being released by the chambers. Charges requiring different treatment and/or duration, especially different case-hardening depths during carburization in a two-stage process, can be simultaneously treated while fully utilizing the capacity of the furnace by irregularly conveying the charges in at least one of the treatment chambers in such a way that the charges are released by the chamber or chambers after varying retention times. The apparatus for carrying out the method has a furnace chamber which is divided into several treatment chambers having different temperature and/or furnace atmospheres, and which is provided with a door for loading the workpiece into the furnace chamber and with a door for withdrawing workpieces therefrom. Each treatment chamber is embodied as a rotary-cycle furnace having selectively and cyclically rotatable hearths. Doors are disposed between the respective treatment chambers.