Nippon Steel Corporation

Ikuo Umehara

Hiroshi Iida

Yasuo Takeda

A method of controlling steel strip temperature in a process of continuously heating steel strip in heating equipment having a preheating zone and a rapid-heating zone. The preheating zone has a number of gas-injecting preheating units that can be individually put into and taken out of operation. In normal operation, the in-operation length of the preheating zone is prefixed irrespective of strip thickness, and the temperature of the rapid-heating zone is preset depending on the strip thickness so that the strip acquires the desired temperature at the exit end thereof. In such operation, the strip is preheated in the preheating zone of the prefixed in-operation length and rapidly heated in the rapid-heating zone at the preset temperature. In irregular operation, such as treating a following strip the thickness of which has changed, the temperature of the rapid-heating zone is changed from the preset one to a second one optimum for the following strip. In the transition period in which the preset temperature of the rapid-heating zone changes to the second one, the in-operation length of the preheating zone is adjusted to control the strip temperature at the exit end thereof. Thus the desired strip temperature at the exit end of the rapid-heating zone can be achieved irrespective of strip thickness.

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Himeji, Japan

Ikuo Umehara