Volume 4, Issue 5 (September 1976)
A Definition of Drawability and Its Relation to Deformation in the Drawing of Square Cups
Drawability is first distinguished from stretchability and the relative amounts of drawing and stretching in any particular forming operation are quantitatively defined. The generalized definition of drawability is based on the definition of the boundary of the product, with which a quantitative definition of draw-in is established. Drawability is then defined as the maximum draw-in at the completion of the cup. It is shown, both theoretically and experimentally, that the draw-in is maximized by choosing the right size, shape, and orientation of the blank to match a particular shape and size of the cup and the boundary. The definition of drawability, hitherto associated with the drawing of round cups, as the Swift test, is generalized to include cups of all shapes. The drawability index so determined can be used not only to compare two materials in the same process, as can be done in the Swift test, but also to compare two processes using the same material, which has hitherto been impossible.