Far-infrared radiation multi-stage type heating furnace for steel sheets for hot stamping

A far-infrared radiation multi-stage type heating furnace comprising heating units and steel sheet support members,

• at least one of the heating units comprising:
• blocks comprising a thermal insulation material, each of the blocks being disposed around a respective horizontal plane of a respective space having rectangular outer shape for accommodating one of the steel sheets for hot stamping;
• and
• far-infrared radiation heaters positioned above and below one of the steel sheets for hot stamping to heat one of the steel sheets for hot stamping,
• the steel sheet support members being disposed within the heating units to support one of the steel sheets for hot stamping,
• the far-infrared radiation heating furnace further comprising support pieces that support the steel sheet support members in such a manner that the steel sheet support members are expandable and contractible in a longitudinal direction by thermal expansion or thermal contracts on,
• the blocks comprising a pair of fixed blocks extending parallel straight and facing each other in a horizontal direction and sandwiching the space in the horizontal plane, a fixed base block sandwiched between lower side of the pair of fixed blocks, a cover block arranged to be opened and closed to open and close an inlet or an outlet of the space that the steel sheet is passed through for hot stamping, and arranged to contact and be sandwiched between upper side of the pair of fixed blocks in a closed position, and the cover block disposed on the fixed base block and directly exposed to an area over the heating unit in the closed position, and the cover block with horizontal length between the pair of fixed blocks at least three times its vertical length.