(19)

(11)

EP 0 428 532 A1

(12)

(43) Date of publication: 29.05.1991 Bulletin 1991/22 (21) Application number: 89907330.0 (22) Date of filing: 29.06.1989

(51) International Patent Classification (IPC):  B21D 13/ 04( . ) (86) International application number: PCT/NO1989/000067 (87) International publication number: WO 1990/000096 (11.01.1990 Gazette 1990/02)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 29.06.1988 NO 19880002881 (71) Applicants: NILSEN, Trond N-1310 Blommenholm (NO) NORMANN, Erling C. N-7650 Verdal (NO)	(72) Inventors: NILSEN, Trond N-1310 Blommenholm (NO) NORMANN, Erling C. N-7650 Verdal (NO) (74) Representative: Bjellman, Lennart Olov Henrik, et al  DR. LUDWIG BRANN PATENTBYRA AB Box 1344 S-751 43 Uppsala S-751 43 Uppsala (SE)