Patent ID: 7334447

Claim:
A method of draw forming a flat sheet annular shaped blank into a three-dimensional nacelle nose cap, the blank having an outer annular portion and a inner annular portion comprising the steps of: (a) obtaining a first female die having a curved arcuate inner wall, (b) obtaining a punch having a curved arcurate outer wall that matches the curved arcuate inner wall of the female die, (b) securing the flat sheet annular shaped blank to the female die, (c) bringing the female die and the punch together to form the flat blank such that the inner annular portion of the blank defines a cup shaped arcuate inner wall conforming to the shape of curved arcuate inner wall of the female die, (d) obtaining a second die having an inside surface matching the curved arcuate inner wall of the blank formed in step (c), the second die further having a curved arcuate outside surface shaped for forming an curved arcuate outer wall in the blank, (e) placing the blank formed in step (c) into the second die so that the cup shaped arcuate inner wall of the blank fits against the inside surface of the second die, (f) securing the cup shaped portion of the blank formed in step (c) to the second die, (g) obtaining a second stage female die having an inside surface generally corresponding to the curved arcurate outside surface of the second die, (i) securing the periphery of the blank to the second stage female die, (i) bringing the second die together with the second stage female die until the inside surface of the of the second stage female die forms the blank against the curved arcurate outside surface of the second die thereby forming an outside annular wall in the blank, the combination of walls in the blank presenting a U-shaped cross section.