Abstract: A forming apparatus (50) includes a roll former (51) operative to roll form a metal strip (100) to form a profiled metal section (10) of generally C section profile including a pan (12) and a pair of upstanding edge margins (14 and 16). The section profile incorporates a longitudinal precamber which is introduced by the forming apparatus by incorporating a prestretching apparatus (52) upstream from the roll former (51), and a bending apparatus (53) located downstream of the roll former (51). The prestretching apparatus differentially stretches the metal strip (100) in its longitudinal direction so as to form portions (101, 102), which are more elongated than a laterally adjacent portion (103) of the strip (100). The differential stretching compensates for longitudinal shortening of the metal strip in forming the profiled section in the roll former (51). The bending apparatus (53) uses a (3) point bending process and includes a reaction stage (60), a fulcrum stage (61), and an action stage (62).

Abstract: A forming apparatus (50) includes a roll former (51) operative to roll form a metal strip (100) to form a profiled metal section (10) of generally C section profile including a pan (12) and a pair of upstanding edge margins (14 and 16). The section profile incorporates a longitudinal precamber which is introduced by the forming apparatus by incorporating a prestretching apparatus (52) upstream from the roll former (51), and a bending apparatus (53) located downstream of the roll former (51). The prestretching apparatus differentially stretches the metal strip (100) in its longitudinal direction so as to form portions (101, 102), which are more elongated than a laterally adjacent portion (103) of the strip (100). The differential stretching compensates for longitudinal shortening of the metal strip in forming the profiled section in the roll former (51). The bending apparatus (53) uses a (3) point bending process and includes a reaction stage (60), a fulcrum stage (61), and an action stage (62).