Deep draw metal stamping manufacturing technology is defined as stretching sheet metal material, commonly referred to as a blank, around a punch. The edges of the metal blank are restrained by blank holders, and the punch is drawn into an upper die cavity to achieve the desired final shape. There are many shapes that can be produced by deep drawing and stamping, such as cups, pans, cylinders, domes, and hemispheres, as well as irregularly shaped products and features.
Deep drawing process:
The total drawing load consists of the ideal forming load plus an additional component to compensate for friction in the contact areas of the flange region, as well as bending and unbending forces at the die radius. The forming load is transmitted from the punch radius through the drawn part wall into the deformation zone (sheet metal flange). Due to the tensile forces acting in the part wall, wall thinning occurs, resulting in non-uniform part wall thickness. It can be observed that the part wall thickness is at its lowest when the wall loses contact with the punch, i.e., at the punch radius. The thinnest part thickness determines the maximum stress that can be transmitted to the deformation zone. Due to material volume constancy, the flange thickens, leading to blank holder contact only at the outer boundary rather than across the entire surface. The maximum load that can be safely transmitted from the punch to the blank sets a limit on the maximum blank size (initial blank diameter for rotationally symmetric blanks). An indicator of material formability is the limiting drawing ratio (LDR), defined as the ratio of the maximum blank diameter that can be safely drawn into a cup without a flange to the punch diameter. Determining the LDR for complex parts is difficult, and therefore the part is examined for critical areas for which an approximation is possible. During severe deep drawing, the material work-hardens, and it may be necessary to anneal the parts in furnaces with controlled atmospheres to restore the material's original elasticity.
Commercial applications of this metal forming process often involve complex geometries with straight sides and radii. In such a case, the term stamping is used to distinguish between the deep drawing (radial tension-tangential compression) and the stretching and bending components (along the straight sides). Deep drawing is always accompanied by other forming techniques in the press. These other forming methods include: deep drawing design drawing
Deep drawing drawing