Extruded hollow section, forming apparatus for forming same, and method for forming same

An extruded hollow section having regions of different wall thickness and formed in a hollow shape by extrusion, the extruded hollow section having a hollow interior defined by an internal periphery thereof, and also having an external periphery, the extruded hollow section comprising:

• parallel parts, wherein the external periphery of said extruded hollow section at said parallel parts has a width, in one direction vertical to a direction of extrusion, which is constant along the direction of extrusion throughout the length of the parallel parts in the direction of extrusion;
• and
• tilt parts, wherein the external periphery of said extruded hollow section at said tilt parts has a width, in the one direction, varying along the direction of the extrusion throughout the length of the tilt parts in the direction of extrusion,
• wherein the parallel parts are integrally formed with the tilt parts, and
• wherein internal peripheries of all of said parallel parts and internal peripheries of all of said tilt parts have the same widths as one another in said one direction throughout the length of said extruded hollow section in the direction of extrusion, whereby the width of the internal periphery of said extruded hollow section in said one direction is the same throughout the length of said extruded hollow section in the direction of extrusion,
• wherein the tilt parts each are formed in a shape asymmetrical with respect to a plane extending in said one direction and containing an axis extending in the direction of extrusion.