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Due to asymmetric configuration of atarget product such as turbine blades including rotor and stator, variousfailures such as scratch, buckling and under-cut derived from sliding andleaning of the intermediate blank are occurred, so it is difficult to controlthe position of large and thick plate in die cavity. Especially, thehollow-partitioned turbine stator has also asymmetric curved surface, so it ishard to adopt a series of draw-bead or blank holder. Thus, the thick plate infree forming process experiences unstable and non-uniform contact on the toolsurfaces in the die cavity. To easy this unstable positioningrestraint in the thick plate free forming, it is necessary to proper design theshoulder angles of the forming punch and the lower die. The rough dimensions ofthe curved turbine stator in this study are a length of 920.0mm, width of360.0mm, and height of 170.0mm, and the thick plate material is stainless steel409L with initial blank thickness of 5.0mm. The shoulder angles are selected tobe 30˚, 45˚, 60˚, 90˚ for the forming punch, and 30˚ and 45˚ for the lower die, respectively. A series of combinations of thetool shoulder angles are numerically examined and simulated to survay thesuitable angle set. ABAQUS Explicit/Implicit codes are used in the numericalinvestigation, furthermore, elastic recovery behavior is also considered. As aresult, both shoulder angle combinations of (90˚, 30˚) and (90˚, 45˚) for the punchand the lower die are shown that the plate position in the die cavity can appropriatelybe controlled, and the deformation behavior suitably realized with respect tothe stress and strain distribution.

Tool Design, Free Forming, Thick Plate, Unstable Blank Support, Finite Element Simulation.