MANUFACTURE OF SQUARE STEEL TUBE OF HIGH STRENGTH

摘要

PROBLEM TO BE SOLVED: To improve the productivity and to reduce the manufacturing cost by installing a heating device on a square steel tube manufacturing line, and performing the stress relieving annealing of the square steel tube to continuously manufacture the square steel tube of high strength. SOLUTION: An electric welding equipment 4 is provided rearward of a forming equipment 1, and each side edge of a steel plate 2 is electrically welded to manufacture a steel tube 5. A heating device 9 to perform the stress relieving annealing of the square steel tube 6 is provided rearward of a corner forming device 7, and the productivity is improved by continuously performing the stress relieving annealing in a square steel tube manufacturing line. In addition, a galvanizing equipment 10 is installed rearward of the heating device 9, and the productivity is improved because the galvanizing can be continuously performed in the square steel tube manufacturing line.