To stably produce a high quality tube corresponding to wide production conditions by pushing up both side edge parts of an open tube before welding from lower part with two sets of pushing up rolls of a seam guide roll device and controlling its pushing up quantity based on the conditions of the amplitude, generating quantity of edge wave of the edge part, the allowable max pushing up quantity of a roll, etc.
A steel strip is formed into a roughly round open tube, its seam parts are welded. In this production method of the welded tube, between a final fin pass roll of a forming process and a squeeze roll of a welding process, a seam guide roll device 11 is arranged inside the open tube 23, by pushing up both edge parts 23a, 23a with two sets of elevatable pushing up rolls 1a, 1b, an edge wave is erased. At this time, pushing up is conducted under three conditions in the following, 1: a pushing up quantity is 1.8-6.5 times of a generated edge wave. 2: Yb=α×Ya, Ya, Yb are a max/min pushing up quantity, α=0.3-1.0. 3: a max pushing up quantity is in the range of a max pushing up load not causing a shape defect.
UEI SEISHI
MIHARA YUTAKA
NAGAHAMA YUTAKA
SATO AKIO
IWASAKI KENICHI
SEKINE YUKIO
TAKAHASHI MASANOBU
Next Patent: METHOD FOR MEASURING EDGE WAVE IN MANUFACTURING WELDED TUBE