Abstract: A method of stretch forming a double curvature panel having corrugations or other surface features formed therein includes providing a reconfigurable forming surface defined by a flexible interpolator sheet mounted on an array of height adjustable pins, the interpolator sheet having a profiled upper surface adapted to form corrugations or other surface features in a workpiece as it is stretched over the forming surface, adjusting the height of each pin to suit the shape of the panel to be produced, placing a workpiece onto the forming surface, and stretching the workpiece over the forming surface such that the profiled upper surface of the interpolator sheet forms the desired corrugations or other surface features in the workpiece.

Abstract: A reconfigurable stretch forming apparatus includes an array of pins adapted to be individually adjustable in height to define a reconfigurable forming surface, a pair of counter-rotating workpiece gripping devices being provided on opposite sides of the array of pins, each gripping device having an arcuate support surface for supporting a workpiece and a clamp member for clamping a work piece against the arcuate support surface, a driver being provided for rotating the counter-rotating gripping devices in opposing directions to stretch the work piece over the forming surface.

Abstract: A method of stretch forming a double curvature panel having corrugations or other surface features formed therein includes providing a reconfigurable forming surface defined by a flexible interpolator sheet mounted on an array of height adjustable pins, the interpolator sheet having a profiled upper surface adapted to form corrugations or other surface features in a workpiece as it is stretched over the forming surface, adjusting the height of each pin to suit the shape of the panel to be produced, placing a workpiece onto the forming surface, and stretching the workpiece over the forming surface such that the profiled upper surface of the interpolator sheet forms the desired corrugations or other surface features in the workpiece.

Abstract: A method of forming a compound curvature metal skin includes providing a blank defining at least a sector of a truncated cone, providing an arcuate or annular punch substantially corresponding in shape to an inner surface of the compound curvature metal skin, gripping a leading edge of a sheet metal blank between mating faces of a first blank holder on a first side of the punch, gripping a trailing edge of the blank between mating faces of a second blank holder on a second side of the punch opposite to the first side, displacing the blank holders with respect to the punch to draw the blank over the punch while permitting the blank to flow between mating surfaces of at least one of the blank holders, including displacing each of the blank holders with respect to the punch by different amounts and at different rates.

Abstract: A reconfigurable stretch forming apparatus includes an array of pins adapted to be individually adjustable in height to define a reconfigurable forming surface, a pair of counter-rotating workpiece gripping devices being provided on opposite sides of the array of pins, each gripping device having an arcuate support surface for supporting a workpiece and a clamp member for clamping a work piece against the arcuate support surface, a driver being provided for rotating the counter-rotating gripping devices in opposing directions to stretch the work piece over the forming surface.

Abstract: Forming a sector for a nacelle lip skin from a sheet metal blank via punch by placing the blank against an outer surface of the punch and clamping a trailing edge of the blank in a clamping member that grips a trailing edge of the blank without slippage; gripping a leading edge of the blank, opposite the trailing edge, in a gripping device at a location axially spaced from the punch with sufficient force to permit the blank to flow therethrough in a controlled manner; displacing the gripping device in a first direction, radially with respect to the punch while drawing the blank through the gripper; displacing the gripping device in a second direction, axially with respect to the punch, to draw the blank over the leading edge of the punch and through the gripping device.

Abstract: A method of forming a sector for a nacelle lip skin from a sheet metal blank comprising the steps of: providing an arcuate or annular punch (7) or mandrel having an inner surface, an outer surface and a leading edge, said punch (7) substantially corresponding in shape to an inner surface of at least a sector of the nacelle lip skin, placing the blank (13) against the outer surface of the punch (7) and clamping a trailing edge of the blank (13) in a clamping means (11,12) to hold the blank (13) against the outer surface of the punch (7), said clamping means (11,12) gripping said trailing edge of the blank without slippage; gripping a leading edge of the blank (13), opposite said trailing edge, in a gripping means (8,9), at a location axially spaced from said punch (7) adjacent and in front of the leading edge of the punch (7), said gripping means (8,9) gripping said blank (13) with sufficient force to permit the blank (13) to flow therethrough in a controlled manner without tearing or wrinkling; displacing the