Rail manufacturing method and rail manufacturing apparatus

Abstract

A method and an apparatus for manufacturing a rail having high ductility in both a head portion and a foot portion. A heated steel rail material is hot-rolled, the temperature is adjusted by cooling the hot-rolled steel rail material, the steel rail material subjected to the temperature adjustment is processed into a rail shape by means of temperature-adjusted rolling at an area reduction ratio of 20% or more, and, in adjusting the temperature of the steel rail material, the surface portions of the steel rail material corresponding to a head portion and a foot portion of the rail shape so that the temperatures of the surface portions reach 500° C. or more and 1,000° C. or less.

1 . A rail manufacturing method comprising:
 hot-rolling a heated steel rail material;   adjusting a temperature by cooling the hot-rolled steel rail material; and   processing the steel rail material subjected to the temperature adjustment into a rail shape by means of temperature-adjusted rolling at an area reduction ratio of 20% or more, wherein,   in the adjusting a temperature of the steel rail material, a surface portions of the steel rail material corresponding to a head portion and a foot portion of the rail shape are cooled so that the temperatures of the surface portions reach 500° C. or more and 1,000° C. or less.   
     
     
         2 . The rail manufacturing method according to  claim 1  comprising:
 after performing the temperature-adjusted rolling, heat-treating the rail until a surface temperature of the head portion of the rail reaches 600° C. or less at an average cooling rate of 1° C./s or more and 10° C./s or less. 
 
     
     
         3 . The rail manufacturing method according to  claim 2  comprising:
 before the heat-treating the rail, re-heating the rail to 730° C. or more when the surface temperature of the head portion of the rail is less than 730° C. 
 
     
     
         4 . The rail manufacturing method according to  claim 3 , wherein,
 in the re-heating the rail, only the head portion of the rail is reheated.   
     
     
         5 . A rail manufacturing apparatus comprising:
 at least one first rolling mill rolling a steel rail material;   a cooling device adjusting a temperature by cooling the steel rail material rolled with the at least one first rolling mill; and   at least one second rolling mill processing the steel rail material subjected to the temperature adjustment into a rail shape by means of temperature-adjusted rolling at an area reduction ratio of 20% or more,   wherein the cooling device cools a surface portions of the steel rail material corresponding to a head portion and a foot portion of the rail shape so that the temperatures of the surface portions reach 500° C. or more and 1,000° C. or less.