| 摘要 |
PURPOSE:To increase the strength of a weld zone by thickening the plate thickness at both side end parts of a blank material via an edger rolling mill, etc., prior to forming of a welding pipe, the by performing the forming by a roll forming machine. CONSTITUTION:The edger rolling mill 1 enabling a width rolling reduction is provided at the inlet side of the roll forming machine consisting of a side roll 11 and horizontal roll 12, 12a, 12b, 12c. The forming material 2a forming a plate thickness increasing part near both the side end parts is formed by performing the width rolling reduction with preventing the buckling of a blank material 2 by the upper and lower pressing rolls 3 by leading the blank material 2 having uniform plate thickness into the edger rolling mill 1. Then, the welding pipe is formed by performing the bend forming of this forming material 2a. The plate thickness increasing part of both side end parts of the blank material 2 becomes in the same plate thickness as those of the other parts by the strong contact pressure in forming and the welding butt shape is improved. Consequently, the strength at the weld zone of the welding pipe is increased.
|
