First   Previous   Next   Last      Index   Text  

Slide 49 of 69

Notes:

    Deep drawing differs from stamping/pressing in that the starting sheet of flat brass is is larger than the area of the punch and the outer parts of the sheet are drawn in towards the die as the operation proceeds. A pressure plate fixed to the power press prevents wrinkling of the edges during “drawing in”
    A deep drawn component may show regions near the edges that are thicker than the original sheet (the thickening being caused by the drawing in process) and regions which are thinner than the original sheet due to local elongation.
    The process is limited by the possibility of fracture occurring during drawing, however cups may be redrawn to a deeper depth after an interstage anneal.
    For deep drawing operations the quality of strip required should be non-directional and of the correct combination of hardness and grain size for the tooling. Directionality leads to 'earring' of drawn cups, a large grain size leads to 'orange peel' surface effects and too high a hardness can limit drawability. Wrinkling, tearing and similar problems can often be caused by incorrect tooling, so tooling geometry and clearances, clamping and drawing forces and lubricant supply also need to be reproducibly controlled.