| 摘要 |
<p>4071US When a blank is cut from metal sheet which suffers from crystallographic anisotropy, there is a tendency for ears to be formed during subsequent forming operations, such as drawing or pressing. In order to compensate for this tendency, there may be used a metal blank which is not completely round, but has lobes at positions to cancel at least some of the valleys between the ears. There is described a punch and die which may be used to form such a lobed blank The punch has four circumferentially extending lobeforming sections each lobe-forming section is constructed by forming a stepped recess in the cutting edge of the punch In each lobe-forming section, the depth of the recess varies from a maximum at the middle of the section to zero at the ends. The die is conventional.</p> |
