Development of a reconfigurable tool for forming aircraft body panels

Abstract To significantly cut the time and cost of tooling development, a reconfigurable discrete die (that is, matrix of individually actuated pins) is being developed for aircraft fuselage parts made by forming sheet metal or molding of composite materials. Each pin in the die is a simple hydraulic actuator outfitted with an in-line NC solenoid valve to control its vertical position. Pin positions can either be set in a closed or open-loop fashion. Once the pins are “set,” then the entire matrix is clamped into a rigid tool. A single pin was constructed to resolve several design issues, including the removal of trapped air in the hydraulic circuit, prevention of hydraulic leakage, motion control, and quantifying the dynamic frictional forces. Because the performance of the single pin was deemed acceptable, a 4 × 4 test die of similar design has been constructed to establish the frictional interactions between adjacent pins, the workability of the pin matrix clamping scheme, and the feasibility of closed and open-loop control of pin positioning.