A method of making a vehicular subassembly includes a step for providing a roof header comprising a hollow member having a long axis, a short axis, and an outer surface that includes a flange. The method also includes a step of stretch bending the member such that the outer surface is substantially in tension and curved in the short axis direction. The method further includes a step of cutting a plurality of notched elements into the flange to reduce strain from the stretch bending step. In some aspects, the step of cutting can be conducted before the stretch bending to reduce strain in the header associated with the subsequent stretch bending.

Provided are a bending apparatus and a bending method. According to an aspect of the present invention, there is provided a bending apparatus including a guide portion configured to guide a movement and a bending of a flexible substrate so that the flexible substrate is bent and moved, a first fastening portion configured to fix one side of the flexible substrate that is bent along the guide portion, a second fastening portion configured to fix an other side of the flexible substrate, and a driving portion configured to move at least one of the first fastening portion and the second fastening portion.

Provided are a bending apparatus and a bending method. According to an aspect of the present invention, there is provided a bending apparatus including a guide portion configured to guide a movement and a bending of a flexible substrate so that the flexible substrate is bent and moved, a first fastening portion configured to fix one side of the flexible substrate that is bent along the guide portion, a second fastening portion configured to fix an other side of the flexible substrate, and a driving portion configured to move at least one of the first fastening portion and the second fastening portion.

Provided is a molding method for a plate-shaped workpiece including forming a concave portion (11) at one surface (1a) of a plate-shaped workpiece (1), and bending the plate-shaped workpiece (1) having the concave portion (11) such that the one surface (1a) becomes a concave surface and a rear surface (1b) thereof becomes a convex surface.

Provided is a molding method for a plate-shaped workpiece including forming a concave portion (11) at one surface (1a) of a plate-shaped workpiece (1), and bending the plate-shaped workpiece (1) having the concave portion (11) such that the one surface (1a) becomes a concave surface and a rear surface (1b) thereof becomes a convex surface.

A method of shot peening according to the present invention includes: placing a jig having an appropriate dimension at one face side of a stamped workpiece; and performing shot peening on another face side of the workpiece in a state where the jig is placed at the one face side of the workpiece, and conforming the workpiece to the jig. At this time, the shot peening may be performed in such a way that residual stresses in the inner side and the outer side of the curved part of the workpiece will become compressive stresses.

A method for precision forming by continuous free bending starts with establishing a correlation equation of a continuous axis f(x) to a bending radius R and determining a bending radius R at a real-time location in the axis. Based on the free bending technique, the method further involves establishing a correlation model of a real-time bending radius R of a tube to an eccentric distance U of a bending die and hence correlations of the equation of the axis to free bending parameters, and constructing a complete correlation model among f(x), R, U, and t based on a relational equation of an eccentric distance U to movement time t of the bending die to enable the precision forming of a complex component by continuous bending. Accordingly, the production efficiency can be improved.

A method for precision forming by continuous free bending starts with establishing a correlation equation of a continuous axis f(x) to a bending radius R and determining a bending radius R at a real-time location in the axis. Based on the free bending technique, the method further involves establishing a correlation model of a real-time bending radius R of a tube to an eccentric distance U of a bending die and hence correlations of the equation of the axis to free bending parameters, and constructing a complete correlation model among f(x), R, U, and t based on a relational equation of an eccentric distance U to movement time t of the bending die to enable the precision forming of a complex component by continuous bending. Accordingly, the production efficiency can be improved.

A workpiece processing method includes: a section roll forming step of subjecting a flat plate shaped workpiece to forming to impart a prescribed cross-sectional shape thereto; a solution heat treatment step of subjecting the workpiece, after the section roll forming step has been performed, to solution heat treatment; a contour roll forming step of subjecting the workpiece, after the solution heat treatment step has been performed, to forming to bend the workpiece into an arcuate shape; and a stretch forming step of subjecting the workpiece, after the contour roll forming step has been performed, to forming to impart a curved shape, following a curved surface of a die, to the workpiece by bringing the workpiece into contact with the curved surface and inputting a tension load to the workpiece.