Patent ID: 6105693
Filing Date: 2000-08-22
Classification: E21B

Abstract:
A partially enhanced drill bit for percussive drilling comprising:a bit body;at least one annular row of non-enhanced buttons (11;11') mounted in the bit body; andat least one annular row of enhanced buttons (12;12') mounted in the bit body radially outside of the non-enhanced buttons;said at least one annular row of non-enhanced buttons (11;11') and said at least one annular row of enhanced buttons (12;12') partly overlapping each other,characterized in that there is an axially extending shoulder (19;19') radially outside of the non-enhanced buttons (11;11') and in that there are chamfers (20;20') at least partly surrounding the enhanced buttons (12;12') and that these chamfers (20;20') interrupt said shoulder (19;19') in the circumferential direction.