| 摘要 |
PURPOSE:To carry out uniform heat treatment so as to enhance accuracy and lessen temperature change range by a method wherein a transfer speed of a material to be heated and induction heating coil number are selectively controlled by reduction ratio of temperature change width calculated from a temperature change width or the like of each portions of a rolled steel pipe to standard heating condition and programed temperature change width. CONSTITUTION:In case of heating a rolled steel pipe such as a seamless steel pipe or the like uniformly by electric induction, one hand or both of a transfer speed of a material to be heated and induction coil stage number for uniform heating are controlled by a ratio of a standard temperature change width DELTAtheta and desired temperature change width DELTAtheta', that is, temperature change width reduction ratio DELTAtheta'/DELTAtheta=alpha. Moreover, a standard temperature change width DELTAtheta is a temperature change width of each portions of a rolled steel pipe against a predetermined standard heating condition or a temperature change width calculated from biased thickness ratio of a rolled steel pipe preriminarily meausred. By this method, even if a thickness of a steel pipe wall is changed, a change width of heating temperature can be reduced and uniform heating is carried out. |
