| 摘要 |
PROBLEM TO BE SOLVED: To make a speed control by sizing rolls possible even when the holding of a strip material by forming rolls is imperfect, and to prevent a resistance welded tube from defective welding. SOLUTION: In this manufacturing method, a form rolling process performing form rolling by form rolling rolls 14, 16 while traveling a strip material T, a tube forming process forming the strip material to a C-shape in cross-section through a forming roll group 26, a welding process welding both end edges of the strip material T whose cross-section has been formed to the C-shape by butting them after heating by a high frequency heating coil 30 and a sizing process contracting the diameter of a metallic tube P after welding through plural sizing rolls 38, are made one line. The forming roll group 26 does not include drive rolls abutting on a form rolling surface. An average load required when the sizing rolls 38 abut on the metallic tube P, must be 150 to 200% of an average load required when the forming rolls 26 abut on the strip material T. A soluble aqueous solution with a concentration of 0.5 to 10 wt.% is supplied to individual sizing roll 38 as lubricating liquid.
|
