(19)

(11)

EP 0 920 567 A1

(12)

(43) Date of publication: 09.06.1999 Bulletin 1999/23 (21) Application number: 97935946.0 (22) Date of filing: 15.08.1997

(51) International Patent Classification (IPC):  E21B 7/ 02( . ) E21B 15/ 04( . ) E21B 15/ 00( . ) E21B 19/ 08( . ) (86) International application number: PCT/SE1997/001351 (87) International publication number: WO 1998/007952 (26.02.1998 Gazette 1998/08)

(84) Designated Contracting States: AT CH DE ES FI FR IT LI (30) Priority: 22.08.1996 SE 19960003039 (71) Applicant: ATLAS COPCO ROCK DRILLS AB 70114 Orebro (SE)	(72) Inventor: PERSSON, Lars S-703 63 Örebro (SE) (74) Representative: Grundfelt, Erik Gunnar, et al  Atlas Copco Rock Drills AB, Patents 701 91 Örebro 701 91 Örebro (SE)