Hardening long workpieces in pit furnace - lifting into a hood, excluding air, during transfer from furnace to quenching tank

摘要

Workpieces are hardened by heating in a pit-type furnace to the required temp. The pieces are then lifted into a hood, which provides protection from the surrounding air while the hood and the workpieces are aligned over a quenching tank; and the hood remains over the quenching tank until the workpieces are completely immersed in the quenching liq. Pref. plant includes a furnace located alongside a quenching tank under a track fitted with trolley hoists. One hoist carries a hood which can be aligned over the furnace while a chain clamp engages with a jig from which the workpieces are suspended. Arrangement is esp. for hardening of workpieces 2-5 m long which can be quenched in oil, water or molten salt.