| 摘要 |
PURPOSE:To manufacture various rails having from medium to high strengths together with various superior characteristics, by varying distance between nozzle and head part of rail, and cooling the rail for a prescribed time, at the cooling by jetting gaseous cooling medium from nozzle to head part of high temp. rail. CONSTITUTION:The rail 1 at high temp. of Ar3 or above after hot rolling or heated for the heat treatment is transferred toward cooling apparatus in length direction at rightly standing posture. Thereat, in case an upper nozzle header 2 surrounding annularly head part of rail in cooling apparatus is used, the distance H between the header 2 and rail head part is set by a prescribed formula from predetermined carbon equivalent of rail, the desired hardness until 10mm depth from surface of rail head part, air quantity for cooling and upper header pressure. The header 2 is previously moved upwardly and downwardly by an elevator 4, and rail is cooled for >=(0.336thetas-150)sec by denoting surface temp. at head top surface of rail measured by a thermometer 5 at inlet side of cooler as thetas.
|
