(19)

(11)

EP 3 631 167 A1

(12)

(43) Date of publication: 08.04.2020 Bulletin 2020/15 (21) Application number: 18722088.4 (22) Date of filing: 20.04.2018

(51) International Patent Classification (IPC):  E21F 16/02(2006.01) (86) International application number: PCT/FI2018/050280 (87) International publication number: WO 2018/220259 (06.12.2018 Gazette 2018/49)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (30) Priority: 31.05.2017 FI 20175488 (71) Applicant: Norrapro Oy 80100 Joensuu (FI)	(72) Inventors: SAARIKIVI, Kai 80110 Joensuu (FI) VÄISTÖ, Harri 80110 Joensuu (FI) (74) Representative: Papula Oy  P.O. Box 981 00101 Helsinki 00101 Helsinki (FI)