| 摘要 |
PURPOSE:To eliminate the instability at the time of unbending, by bend-forming the central part, both side edges and their vicinities of the width of a metallic strip in the regular direction, and bend-forming the middle parts between the central part and both ends and their vicinities in the reverse direction. CONSTITUTION:A material 1 to be fromed is bend-formed in the regular dirction. by pressing it from its inside and outside by a central roll 3, edge rolls 4, 4, and a lower roll 7 provided with grooves corresponding to respective rolls. Because the central part is bend-formed in the regular direction, the material 1 is bitten by the succeeding roll stands while restricting correctly its left and right positions by utilizing the central part as a guide face. Further, in unbending and bending in the regular direction the left and right reversely bent parts, a lateral movement of the material 1 is prevented even if an unbalanced force acts laterally on the material 1, and the instability is prevented. |
