Sweep forming assembly and method

Abstract

A method and apparatus produces a roll formed bumper member comprising of a metal material. The bumper member has a predetermined transverse cross section and a predetermined curvature. A strip bumper structure is fed into a forming assembly along a line level. The bumper structure has the predetermined transverse cross section and an essentially straight longitudinal configuration. The forming assembly has a driven support roller and a pair of driven cooperating flexing rollers. A first roller of the pair of flexing rollers is positioned to deflect the bumper structure out of the line level. A second roller of the pair of flexing rollers is mounted to revolve about the first roller. The support roller and the pair of cooperating flexing rollers are driven for feeding the bumper structure between the pair of cooperating and counter rotating flexing rollers. Revolving the second flexing roller about the first flexing roller flexes the bumper structure between the support roller and the first flexing roller imparting a permanent longitudinal curvature to the bumper structure.

1 . A bumper constructed of a roll formed metal material, comprising an elongated roll formed bumper member ( 47 ) having a predetermined transverse cross section and a longitudinal extent, said predetermined transverse cross section having one at least partially open side, said bumper being characterized in that said longitudinal extent hasa predetermined bumper sweep of about 80 and said metal material having an MPa of at least 827.  
   
   
       2 . A bumper as claimed in  claim 1  wherein said metal material is a martinsitic steel.  
   
   
       3 . A bumper as claimed in  claim 2  wherein said metal material is a steel that has a minimum 0.2 percent offset yield strength of about 120,000 psi (827 MPa) and a ferritic grain structure.  
   
   
       4 . A bumper as claimed in  claim 3  wherein said bumper member has a thickness of less than approximately 2.0 mm.  
   
   
       5 . A bumper as claimed in  claim 1  wherein said metal material is a quenched and tempered steel having a minimum ultimate tensile strength of about 140,000 psi (965 MPa) and a grain structure comprised of ferrite and tempered martinsite.  
   
   
       6 . A bumper as claimed in  claim 5  wherein said bumper member has a thickness of less than approximately 2.0 mm.  
   
   
       7 . A bumper as claimed in  claim 1  wherein said metal material is a quenched and tempered steel having a minimum ultimate tensile strength of from about 190,000 to about 220,000 psi (from about 1310 MPa to about 1516 MPa) and having a tempered martinsite grain structure.  
   
   
       8 . A bumper as claimed in  claim 7  wherein said bumper member has a thickness within the range of approximately 0.8 mm to approximately 1.6 mm.  
   
   
       9 . A bumper as claimed in  claim 8  wherein said bumper member has a thickness within the range of approximately 1.0 mm to approximately 1.3 mm.