公开(公告)号：EP1815921A4

公开(公告)日：2008-07-23

申请号：EP04808175

申请日：2004-12-27

申请人： NAKATA MFG COMPANY LTD

发明人： WANG FEIZHOU ,  NAKANO TOMOYASU ,  KIUCHI MANABU

IPC分类号： B21D15/02 ,  B21B17/14 ,  B21B27/02 ,  B21C37/15

CPC分类号： B21C37/155 ,  B21B17/14 ,  B21D5/12 ,  B21D15/02

摘要： Rolls for molding a square tube and a method and a device for rollingly molding the square tube capable of manufacturing the square tube having accurate dimensions and shape and having excellent internal quality at low cost by rollingly molding a circular tube to the square tube with shared rolls without imparting excessive load on a raw material at predicted portions for corner parts and shoulder parts. The radius of curvature of the surface of the molding roll in the axial direction is formed so that the linearization of the portions (predicted shoulder portions of the raw tube) adjacent to the predicted corner portions of the square tube can be performed in preference to the other portions (other predicted side part portions) of the raw tube. For example, a stand formed of four-side rolls is disposed on the upstream-most side and downstream-most side molding roll stands, and a stand formed of two-right and left side rolls is disposed therebetween. Since the molding roll formed to have the radius of curvature constricting the portion of the raw tube forming the shoulder parts adjacent to the corner parts of the square tube smaller than that constricting the portion of the raw tube forming the side part center of the square tube in cross section is adopted, an optimum balance can be kept between a roll sharing effect and an equipment cost, and the square tube excellent in quality can be manufactured at low cost with the shared roll.