Determination of the process window in hydromechanical deep drawing

Hydromechanical Deep Drawing (HDD) is one of the most effective methods used to increase the formability of materials in sheet metal production. In this method, the liquid pressure is applied from the opposite side of the sheet while the sheet material is deep drawn with the help of stamping. The increased frictional force between the sheet and the stamp which is caused by the pressure in the opposite direction, prevents the localization of the stresses, delays the tear damage and significantly increases the limit drawing ratio of the sheet materials. The limit drawing ratio value which is around 2 in classical deep drawing process, can be increased up to 2.75 in the hydromechanical deep-drawing process. Determining the optimum values (loading profiles) of fluid pressure and blank holder force, which must be applied varyingly depending on the amount of punch movement in the HDC process, is a difficult task. If proper loading profiles are not used, tearing or wrinkling damage may occur in the part. Therefore, diagrams are needed to show how the target part will behave in the manufacturing process (maximum thinning, tearing, wrinkling and pressure leaks) and how the parameter values that will affect the production quality have changed. These diagrams are called Process Window (PW). By using PW, workpieces can be produced in optimum quality. In this thesis, PW was obtained for the production of AISI 304 stainless steel teapot part without wrinkling, which can be produced wrinkled by the HDD process without applying process window. The liquid pressure and blank holder force required to produce the teapot without damage, process windows are numerically created. The obtained PW's obtained were confirmed by experiments. As a result, the wrinkle damage in the teapot part was decreased by using PWs and the part production was successfully realized.