The specification discloses a forming die or ram movable along a guideway or track by a pair of toggle-joint linkages to move from a column of staples a staple having a downwardly bowed central portion into engagement with an anvil, then bend outer portions down over the anvil to drive pointed legs into...http://www.google.com/patents/US4256251?utm_source=gb-gplus-sharePatent US4256251 - Surgical staplers and staple
