Method of and apparatus for joining hot materials to be rolled to each

Abstract

In a continuous hot rolling system, at least one melt-cut torch is set in a predetermined positional relationship with respect to a trailing end of a preceding hot material and a leading end of an adjacent succeeding hot material. An injected flow of cutting gas from the melt-cut torch is blown against a portion of at least one of the trailing end of the preceding material and the leading end of the succeeding material to melt-cut the portion. The portion extends from an end surface of the one end over a predetermined length. The trailing end of the preceding material and the leading end of the succeeding material are forced against each other and are butt-joined to each other. By doing so, there are produced joining surfaces superior in surface accuracy and high in temperature, to allow joining to be high in accuracy and strength. This joining may be made with respect to slabs before rough rolling, or may be made with respect to bars after rough rolling. Further, a slab manufactured by a continuous casting machine are reduced in thickness at a plurality of desired locations to form a plurality of thickness-reduced portions. Cutting is made at the thickness-reduced portions. The cut thickness-reduced portions are joined to each other. Furthermore, the ends of the respective materials after having been cut are reduced in thickness with the ends abutted against each other to form thickness-reduced portions. The thickness-reduced portions are joined to each other.