In a tip for a ball point pen including a cylindrical metallic tip body having a pointed end, a ball receiving hole having its opening at the pointed end of the tip body, a ball supporting seat of a plastic held in the bottom of the ball receiving hole, a bore for delivering ink to the ball receiving...http://www.google.es/patents/US4251164?utm_source=gb-gplus-sharePatente US4251164 - Tip for ball point pen
