JPS57187113A - Manufacture of square steel pipe - Google Patents

Abstract

PURPOSE:To finish forming a square steel pipe having a prescribed shape after rolling nearly all the formed portions to improve the forming accuracy, by roll- forming a welded pipe through plural driving type rolling rolls after rolling it through non-driving type rolling rolls, in a continuous roll forming process. CONSTITUTION:A steel pipe, formed in a continuous roll forming process, is cooled after passing through squeezing rolls 4 to be roll-formed through a sizing roll stand 6 to enhance its roundness and then, is fed into a Turk's-head stand 10. Thus, almost a half of the whole amount of forming, in forming square pipe, is rolled because of using idle rolls. Next, the pipe is fed into four sides rolling stands 20 and is finished into a square pipe having a prescribed shape through the two stages of four sides rolling stands 20 while being roll-formed to obtain a propelling force by driving rolls.