FAR-INFRARED MULTISTAGE HEATING FURNACE FOR HOT-PRESSED STEEL PLATE

摘要

The purpose of the present invention is to provide stable support over an extended period of time to a hot-pressed steel plate which is accommodated within a far-infrared multistage heating furnace, using steel plate support members that have a small planar projected area and minimized thermal deformation. This far-infrared multistage heating furnace has: a heating unit and a ceiling unit provided in multiple stages in the vertical direction, the heating unit and ceiling unit accommodating a hot-pressed steel plate comprising an aluminum-plated steel plate or a zinc-plated steel plate; and far-infrared heaters arranged inside the heating unit and the ceiling unit, the far-infrared heaters heating the hot-pressed steel plate to at least the Ac3 transition point but no higher than 950°C. Within the heating unit are arranged steel plate support members for supporting the hot-pressed steel plate through point contact or line contact against the hot-pressed steel plate, the steel plate support members being supported so as to be capable of expanding and contracting in the longitudinal direction due to thermal expansion or thermal shrinkage.