GRADIENT HEATING METHOD FOR BILLET AND BATCHWISE GRADIENT HEATER FOR BILLET

摘要

PROBLEM TO BE SOLVED: To provide a gradient heating method for a billet for extrusion which can surely and rapidly impart a desired temperature gradient in the longitudinal direction of the billet without the occurrence of heating temperature unevenness in the billet. SOLUTION: This gradient heating method for the billet comprises heating the billet by bringing pure oxygen or the combustion flame from an oxygen enriching burner into collision against the entire outer peripheral surface in the entire longitudinal direction of the billet and controlling the pure oxygen on a charging side of an extruder in the ensuing process step of the billet or the combustion capacity of the oxygen enriching burner higher than the pure oxygen or the combustion capacity of the oxygen enriching burner on the other end side.