(19)
(11) EP 4 800 216 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
07.10.2026 Bulletin 2026/41

(43) Date of publication A2:
02.09.2026 Bulletin 2026/36

(21) Application number: 26185460.8

(22) Date of filing: 18.06.2024
(51) International Patent Classification (IPC): 
E21B 4/14(2006.01)
E21B 17/07(2006.01)
 E21B 10/36(2006.01)
(52) Cooperative Patent Classification (CPC):
E21B 4/14; E21B 10/36; E21B 17/076
(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 ME MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA
Designated Validation States:
GE KH MA MD TN

(62) Application number of the earlier application in accordance with Art. 76 EPC:
24182804.5 / 4667703

(71) Applicant: Sandvik Mining and Construction Oy
33330 Tampere (FI)

(72) Inventors:
  • BRUANDET, Olivier
    33330 Tampere (FI)
  • KOSKINEN, Jouni
    33330 Tampere (FI)

(74) Representative: Sandvik 
Sandvik Intellectual Property AB
811 81 Sandviken
811 81 Sandviken (SE)

   


(54) SPLINE ALIGNMENT FOR DTH HAMMER ASSEMBLY


(57) A hammer drill assembly for coupling to a drill string having a drill bit positioned at the forward end having a drill head and a bit shaft; wherein a plurality of axially extending bit splines project radially outwards from a radially outward facing surface of the bit shaft; wherein each of the bit splines comprises a bit spline tip at its axially rearward end having a rearward axially outer edge and a central bit spline longitudinal axis; and a driver sub provided axially rearward of the drill bit comprising a plurality of axially extending driver sub splines projecting radially inwards from an inward facing surface of the driver sub; characterised in that: the rearward axially outer edge on at least of one of bit spline tips is non-perpendicular to the bit spline longitudinal axis along at least 25% of the width of the bit spline tip.







Search report









Search report