| 摘要 |
PROBLEM TO BE SOLVED: To provide a welded tube manufacturing apparatus, which applies restraint on joining edges by rolls preventing most of local wall thickness deviation caused by misalignment of thin gage material and thickness gap at the welded edges in a forming process for welding. SOLUTION: In the manufacturing apparatus for a welded metal tube by roll forming a flat plate 1 into a tubular shape, caliber rolls (2, 2, 5, 5) are arranged right and left in 2 stages in the direction of tube forming. Between front and rear stages of the caliber rolls (2, 2, 5, 5), a welding device 6 is installed. Contacting with both edges of tubular-formed plate before welding point, a convex caliber roll 4 inside the both edges of the tubular-formed plate and a concave caliber roll 3 outside are provided to apply restraint on the welding portion from both inside and outside of the plate near the butting point of both plate edges performing excellent butt welding.
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