Conduit making machine with diameter control and method

摘要

A machine and method for making spiral pipe from a continuous strip of sheet metal including a corrugating mill which forms corrugations in the strip and drives it through a three-roll bending mill which bends the strip into helical convolutions and guides adjacent edges thereof into an interlocking relationship and a pair of lock up rolls for crimping the interlocked edges of the convolutions into a continuous seam, which rolls are manually or automatically adjustable radially relative to the pipe axis whereby its diameter may be accurately controlled. Adjustment of said rolls radially inwardly effects a diameter increase whereas adjustment outwardly decreases the diameter of the pipe.