(19)
(11) EP 0 385 959 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
03.07.1991 Bulletin 1991/27

(43) Date of publication A2:
05.09.1990 Bulletin 1990/36

(21) Application number: 90850080.4

(22) Date of filing: 27.02.1990
(51) International Patent Classification (IPC)5: E21B 4/14
(84) Designated Contracting States:
DE FR GB SE

(30) Priority: 02.03.1989 US 317866

(71) Applicant: SANDVIK AKTIEBOLAG
S-811 81 Sandviken 1 (SE)

(72) Inventor:
  • Meek, James Frank
    Houston, Texas 77092 (US)

(74) Representative: Eriksson, Kjell et al
Sandvik AB Patent Department
811 81 Sandviken
811 81 Sandviken (SE)


(56) References cited: : 
   
       


    (54) Percussion drill


    (57) A percussion drill includes a control arbor (18) in which a hammer piston (70) is longitudinally reciprocably disposed. Front (34) and rear (36) casing sections are threadedly coupled to the control arbor (18) in a manner preventing longitudinal movement of the arbor relative to the casing sections. A drill bit (50) is secured to the front casing section (34), and is repeatedly struck by the piston (70) to effect a percussion drilling operation. A rear sub (46) is secured to the rear casing section (36), and a front end (64) of the rear sub projects telescopingly into a rear end (63) of the control arbor to radially support the latter.






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