JPS5591937A - Heat treatment apparatus for long side material - Google Patents

Abstract

PURPOSE:To heat a steel pipe uniformly in a short time, by heating the tip end previously before introducing in a heating furnace and tempering furnace, at the time of heat-treating the long sized steel pipe having a thick wall or large diameter end part. CONSTITUTION:The continuous length steel pipe (a) having a the thick, large diameter part (b) at the end part by upset, is moved on the inlet table 1 at first and then, is placed on transferring line for the heating furnace 3. At this time, the pipe (a) is put in the furnace 3 after heating the end part (b) of the pipe (a) in the preheating furnace 10 previously while the pipe (a) is moved on the table 1. The pipe (a) is heated while the pipe (a) is moved in the furnace 3 and the part (b) is heated at the same uniform temperature to the thin part of central part of the pipe 1 because the part (b) is preheated. Tempering treatment is carried out at a uniform temperature in the tempering furnace 8 after hardening in the hardening apparatus 5 and preheating the part (b) by the preheating furnace 11 when the pipe is moved by the transfer table 6. Exsisting time in the furnace 3 and 8, is able to shorten and operation efficiency is improved and also, fuel expense is reduced.