| 摘要 |
PURPOSE:To prevent a disconnection at wire drawing time and the outer tube weld zone being opened by making the ratio of the thickness of an outer tube to that of an inner tube at the value in specified range and the degressive rate of the outer tube at more than the specified value in case of the manufacture of the seamless fluxed core wire for welding a multiple tubular shape fine diameter. CONSTITUTION:The strip steel H1 for outer tube forming is formed in the circular arcuated shape of a half moon by forming rolls 1, 2, shunted with the inner tube 1 filling the flux for welding inside by a guide G1, the inner tube 1 is wrapped by a circular arcuated strip steel H1 by forming rolls 3, 4 and both edge abutting parts of the outer tube H1 are welded by a seam welding machine 3. This is subjected to wire drawing in the wire shape of <=2mmphi by wire drawing machines A, B by rounding it by forming rolls 5-7. In this case the ratio of the thickness t1 of the strip steel for outer tube and that t2 of inner tube 1 is then at the value of the range of 1.5<=t1/t2<=6 and yet the degressive rate of the outer tube by wire drawing at >=90% and the seamless flux cored wire for welding multiple tubular shape whose diameter is in <=2mmphi is stably manufactured. |
