A turbofan mixer is fabricated from a structural panel of the variety including substantially planar first and second walls and a filler material sandwiched therebetween. The mixer includes at least one acute angle formed by bending the structural panel about a portion of the first wall, whereby the first wall forms the interior and the second wall forms the exterior of the angle. The first and second walls are protected from crushing and stretching proximate the apex of the angle during the bending process by the prior or contemporaneous deformation of the aforementioned portion of the first wall into a form having a plurality of repetitive waves in the cross section thereof, whereby the first wall is reduced in length relative to the smooth outer wall. The first wall may be deformed by contact with a toothed roller or a reciprocable die or by other appropriate means.
A method is provided of forming a circular chuted axially extending mixer from an originally circular scalloped, radially extending ring blank. The method utilizes a common mechanical press with male and female die portions. The female portion is pressed down over the blank against the male portion to form a convolution in the blank, with progressively increasing height. Successive convolutions are formed which tends to gather together the radially outer portion of the blank thereby straightening its originally circular shape. Repeating this process forms a relatively straight band having convolutions forming chutes therebetween. Individual chuted bands can be joined together to form a single circular chuted axially extending mixer.
