MATHOD FOR CONTROLLING EXTRACTION PITCH OF SEAMLESS STEEL PIPE FROM HEATING FURNACE

摘要

PURPOSE:To increase the efficiency of heating and rolling lines to maximum limit in manufacturing a seamless steel pipe from a round steel slab by controlling the extraction pitch of the round steel slab from a heating furnace on the basis of the down time between each treating time in respective processes. CONSTITUTION:A round steel slab heated with a rotary heating furnace 1 is pierced with a piercer 3 via a centering machine 2 to work a shell. After the shell is subjected to the middle rolling and the thickness rolling with an elongeter 4 and a mandrel 5, it is drawn to a prescribed outer diameter with a sizer 6 and rolled to make a blank pipe. It is preliminarily cut with a hot saw 7 and sent to an annealing apparatus 8 or the first cooling bed 9 and subjected to crook removing with a corrector 10. After the annealed pipe is tempered with a tempering furnace 11, the outer diameter is corrected with a sizer 12 and the pipe is sent to a corrector 10. The operation efficiency of the heating and rolling lines is increased to maximum limit by calculating the down time of the treatment in respective processes and controlling the pitch in which the round steel slab is extracted from the heating furnace 1 on the basis of the difference between the minimum down time among the calculated down time and the preliminarily preset down time.