Patent ID: 6988390

Claim:
Method for making a workpiece ( 2 ) comprising at least one tubular section ( 3 , 3 ′, 4 , 4 ′) obtained by bending a metal plate ( 10 ) along at least one longitudinal line of bending ( 12 – 17 ) intermediate opposite edge portions of the metal plate, the method including the steps of: initially pre-bending (F) said plate ( 10 ) along at least two lines of bending ( 12 – 17 ) to thereby define at least two parts ( 23 – 26 ) that are bendable relatively toward one another about the at least two longitudinal lines of bending; and thereafter applying a bending force (F 1 , F 3 , F 11 , F 13 ) to at least one of the at least two parts to urge the at least one part toward another part of the at least two parts such that the at least two parts at least begin to define a tubular section having inner and outer surfaces and wherein the bending force is applied only along the outer surface and without any forming member within the tubular section being formed while simultaneously applying a clamping force (F 7 , F 8 , F 12 , F 14 ) with respect to the at least one part to urge the at least one part toward one of the at least two lines of bending buy a bending member ( 103 – 106 ) that engages the at least one part along an outer surface thereof and such that the clamping force prevents slipping of the at least one part relative to the bending member as the bending member bends the at least one part.