Continuous flow plug mill system

The method of carrying out plug mill operations on a seamless tubular shell, which comprises

• (a) advancing the shell through a first rolling stage in which the shell is driven through a first mill stand and over a first mandrel supported plug,
• (b) during said first rolling stage, advancing the shell over a mandrel bar,
• (c) upon termination of the first rolling stage, transferring the shell and the mandrel bar contained within it laterally,
• (d) thereafter advancing the shell through a second rolling stage, in which the shell is driven through a second mill stand and over a second mandrel supported plug, and
• (e) stripping the shell from said mandrel bar during the second rolling stage.

A plug mill system for rolling seamless tubular shells, which comprises

• (a) first and second mill stands,
• (b) said second mill stand being spaced longitudinally from said first mill stand a distance greater than the length of a tubular shell after rolling in the first mill stand,
• (c) said second mill stand being offset laterally from said first mill stand,
• (d) a mandrel,
• (e) means for supporting said mandrel in alignment with said first mill stand and on the downstream side thereof during rolling of a tubular shell in said first mill stand whereby, as said rolling progresses, the rolled shell is applied over said mandrel,
• (f) means for laterally transferring the once-rolled shell and said mandrel laterally into alignment with said second mill stand, and
• (g) means for supporting said mandrel during rolling of said shell in said second mill stand, whereby said shell is stripped from said mandrel as rolling progresses in said second mill stand.